february 2, 2012 charleston, south carolina - spaceflight · 22nd aa s /aiaa space flight mechanics...

22nd A AS / AIA A

Space Flight Mechanics MeetingJanuary 29 – February 2, 2012 | Charleston, South Carolina

AAS General ChairMatthew BerryAnalytical Graphics, Inc.

AIAA General ChairKeith JenkinsPatent Attorney

AAS Technical ChairJim McAdamsJohns Hopkins UniversityApplied Physics Laboratory

AIAA Technical ChairDavid McKinleya.i. solutions, Inc.

Conference Program

Cover Images

Top: The MESSENGER spacecraft becomes the first Mercury orbiter on March 18, 2011. Credit: NASA and The Johns Hopkins University Applied Physics Laboratory

Upper Middle: The Dawn spacecraft enters orbit about the asteroid Vesta on July 16, 2011. Credit: Lockheed Martin and NASA/Jet Propulsion Laboratory, California Institute of Technology

Lower Middle: The GRAIL-A and GRAIL-B spacecraft, which entered lunar orbit on December 31, 2011 and January 1, 2012, fly in formation above the Moon. Credit: Lockheed Martin and NASA/Jet Propulsion Laboratory, California Institute of Technology

Bottom: The Space Shuttle Atlantis orbiter lands for the final time on July 21, 2011. Credit: NASA

Cover design by Jason Martin, Analytical Graphics, Inc.

Program printing sponsored by:

22nd AAS/AIAA Space Flight Mechanics Meeting

Table of Contents General Information ........................................................................................................................ 3

Registration ..................................................................................................................................... 3

Schedule of Events .......................................................................................................................... 4

Francis Marion Hotel Layout .......................................................................................................... 6

Special Events ................................................................................................................................. 7

Early Bird Reception ................................................................................................................... 7

Awards Ceremony and Dirk Brouwer Award Lecture ............................................................... 7

Dirk Brouwer Award Honoree .................................................................................................... 7

Offsite Event – USS Yorktown ................................................................................................... 8

Conference Location ....................................................................................................................... 9

The Francis Marion Hotel ........................................................................................................... 9

Transportation Info ..................................................................................................................... 9

Driving Directions ...................................................................................................................... 9

Arrival Information ................................................................................................................... 10

Restaurants ................................................................................................................................ 10

Recreation ................................................................................................................................. 12

Area Map .................................................................................................................................. 14

Additional Information ................................................................................................................. 15

Speaker Orientation .................................................................................................................. 15

Volunteers ................................................................................................................................. 15

Presentations ............................................................................................................................. 15

Preprinted Manuscripts ............................................................................................................. 15

Conference Proceedings............................................................................................................ 15

Satisfaction Survey ................................................................................................................... 16

Committee Meetings ................................................................................................................. 16

Session 1: Formation Flying I ..................................................................................................... 17

Session 2: Space Situational Awareness ..................................................................................... 20

Session 3: Attitude Determination ............................................................................................... 23

Session 4: Asteroid and Near-Earth Object Missions I ............................................................... 26

Session 5: Dynamical Systems Theory I ..................................................................................... 28

Session 6: Formation Flying II .................................................................................................... 31

Session 7: Optimal Control ......................................................................................................... 34

Session 8: Trajectory Optimization I ........................................................................................... 36

Session 9: Attitude Dynamics and Control I ............................................................................... 38

22nd AAS/AIAA Space Flight Mechanics Meeting Page 2

Session 10: Flight Dynamics Operations .................................................................................... 41

Session 11: Dynamical Systems Theory II .................................................................................. 43

Session 12: Spacecraft Guidance, Navigation, and Control I ..................................................... 45

Session 13: Orbit Determination I ............................................................................................... 47

Session 14: Lunar and Planetary Missions .................................................................................. 49

Session 15: Numerical and Analytical Trajectory Techniques ................................................... 51

Session 16: Asteroid and Near-Earth Object Missions II ............................................................ 53

Session 17: Trajectory Optimization II ....................................................................................... 55

Session 18: Attitude Dynamics and Control II ............................................................................ 57

Session 19: Orbital Debris ........................................................................................................... 59

Session 20: Earth Orbital Missions ............................................................................................. 61

Session 21: Orbit Determination II .............................................................................................. 63

Session 22: Spacecraft Guidance, Navigation, and Control II .................................................... 65

Author Index ................................................................................................................................. 67

Papers Sorted By Time Slot .......................................................................................................... 69

Record of Meeting Expenses ........................................................................................................ 76

Conference Satisfaction Survey .................................................................................................... 77


22ND AAS/AIAA SPACE FLIGHT MECHANICS MEETING

CONFERENCE INFORMATION GENERAL INFORMATION Welcome to the 22nd Space Flight Mechanics Meeting, hosted by the American Astronautical Society (AAS) and co-hosted by the American Institute of Aeronautics and Astronautics (AIAA), January 29 – February 2, 2012. This meeting is organized by the AAS Space Flight Mechanics Committee and the AIAA Astrodynamics Technical Committee, and held at the Francis Marion Hotel, 387 King Street, Charleston, South Carolina 29403. Phone: 843-722-0600. REGISTRATION

Registration Site (https://aas.pxi.com/registration/reg)

In order to encourage early registration, we have implemented the following conference registration rate structure: Register by 10 Jan 2012 and save $50!

Category Early Registration (through 10 Jan 2012)

Late Registration

Full - AAS or AIAA Member $450 $500 Full - Non-member $550 $600 Retired* $125 $175 Student* $125 $175 *does not include proceedings CD

The USS Yorktown dinner on Tuesday evening is included with all registrations. Guest tickets for the dinner may be purchased for $50. More information about the Yorktown dinner is included below.

A conference registration and check-in table will be located on the Mezzanine Level of the Francis Marion Hotel and will be staffed according to the following schedule:

Sunday Jan. 29 3:00 PM - 6:00 PM

Monday Jan. 30 7:30 AM - 2:00 PM

Tuesday Jan. 31 8:00 AM - 2:00 PM

Wednesday Feb. 1 8:00 AM – 2:00 PM

Thursday Feb. 2 8:00 AM – 10:00 AM

We will accept registration and payment on-site for those who have not pre-registered online, but we strongly recommend online registration before the conference in order to avoid delays (see URL above). Pre-registration also gives you free access to pre-print technical papers. On-site payment by credit card will be only through the AAS website using a computer at the registration table. Any checks should be made payable to the “American Astronautical Society.”


SCHEDULE OF EVENTS

Day Start End Function Room S

un

day

29

Ja

nu

ary 3pm 6pm Registration Registration Desk

6pm 9pm Early Bird Reception

Colonial

Day Start End Function Room

Mon

day

30 J

anu

ary

7am 8am Speakers Breakfast Colonial 7:30am 2pm Registration Registration Desk 8am 12:10pm Session 1: Formation Flying I Carolina A 8am 11:45am Session 2: Space Situational Awareness Carolina B 8am 12:10am Session 3: Attitude Determination Calhoun 9:40am 10:05am Morning Break Prefunction A 12:15 1:30pm Joint Technical Committee Lunch Pinckney 1:30pm 5:15pm Session 4: Asteroid and Near-Earth Object

Missions I Carolina A

1:30pm 5:15pm Session 5: Dynamical Systems Theory I Carolina B 1:30pm 5:15pm Session 6: Formation Flying II Calhoun 1:30pm 4:25pm Session 7: Optimal Control Colonial 3:10pm 3:35pm Afternoon Break Prefunction A


Tu

esda

y 31

Jan

uar

y

7am 8am Speakers Breakfast Pinckney 8am 2pm Registration Registration Desk 8am 10:55am Session 8: Trajectory Optimization I Carolina A 8am 11:45am Session 9: Attitude Dynamics and Control I Carolina B 8am 11:45am Session 10: Flight Dynamics Operations Calhoun 9:40am 10:05am Morning Break Prefunction A Noon 1:30pm AAS Space Flight Mechanics Committee

Lunch Pinckney

1:30pm 4:50pm Session 11: Dynamical Systems Theory II Carolina A 1:30pm 4:25pm Session 12: Spacecraft Guidance, Navigation,

and Control I Carolina B

1:30pm 4:50pm Session 13: Orbit Determination I Calhoun 3:10pm 3:35pm Afternoon Break 9th Floor Prefunction5:00pm 6:00pm Awards Ceremony and Dirk Brouwer Award

Lecture Colonial

6pm 9pm Offsite Event USS Yorktown



Wed

nes

day

1 F

ebru

ary

7am 8am Speakers Breakfast Pinckney 8am 2pm Registration Registration Desk 8am 11:20am Session 14: Lunar and Planetary Missions Carolina A 8am 11:20am Session 15: Numerical and Analytical

Trajectory Techniques Carolina B

8am 11:45am Session 16: Asteroid and Near-Earth Object Missions II

Calhoun

9:40am 10:05am Morning Break Prefunction A Noon 1:30pm AIAA Astrodynamics Technical Committee

Lunch Pinckney

1:30pm 4:25pm Session 17: Trajectory Optimization II Carolina A 1:30pm 5:15pm Session 18: Attitude Dynamics and Control II Carolina B 1:30pm 5:15pm Session 19: Orbital Debris Calhoun 3:45pm 4:10pm Afternoon Break Prefunction A 5:15pm 6:15pm Conference Administration Subcommittee Carolina A 5:15pm 6:15pm Technical Administration Subcommittee Carolina B 5:15pm 6:15pm Website Administration Subcommittee Calhoun


Th

urs

day

2 F

ebru

ary

7am 8am Speakers Breakfast Laurens 8am 10am Registration Registration Desk 8am 11:20am Session 20: Earth Orbital Missions Carolina A 8am 10:55am Session 21: Orbit Determination II Carolina B 8am 10:55am Session 22: Spacecraft Guidance, Navigation,

and Control II Calhoun

9:40am 10:05am Morning Break Prefunction A


FRANCIS MARION HOTEL LAYOUT

Carolina A Carolina B

Calhoun Room

Colonial Room

Presentation Rooms: Carolina A Carolina B Calhoun Colonial


SPECIAL EVENTS

EARLY BIRD RECEPTION Sunday, 29 January 6 – 9:00 pm Location: Colonial

AWARDS CEREMONY AND DIRK BROUWER AWARD LECTURE Tuesday, 31 January 5 – 6:00 pm (ceremony and lecture) Location: Colonial (ceremony and lecture)

Review of Quadrilateralized Spherical Cube and Views of Future Work on Spacecraft Collisions

The first topic concerns an efficient Earth database structure for rapidly storing and retrieving high-resolution remotely-sensed global data. This formulation is based on the concept of a "Quadrilateralized Spherical Cube" (QLSC). It was implemented for global usage by the Navy in 1977, and since then it has been adopted by other government agencies such as NASA in various applications, the first being the Cosmic Background Explorer (COBE). For the past three decades QLSC, or some derivative of it, has been used by astronomers and astrophysicists for star-mapping and radiation-cataloging to the celestial sphere. Atmospheric and ocean scientists use it for database structure because of its exceptional efficiency in data archiving and retrieval. The QLSC and its associated Quadtree are presently used by computer scientists in many geographical information systems for data processing. It is also used in map projections because there are no singularities at the poles or elsewhere, as is the case with other equal-area mapping schemes. The second topic concerns the modeling and computation of spacecraft collision probability for the case in which the statistics no longer obey Gaussian distributions, or the case where the space debris is so sparse as not to be amenable to description using Poisson statistics. An outline is given for the computation of collision probability of close encounters when the probability density functions are non-Gaussian. A discussion is included on the estimation of debris density when there are pronounced inhomogenieties in the spatial distribution of the debris.

DIRK BROUWER AWARD HONOREE Ken Chan obtained his Bachelor’s degree from the University of Pennsylvania, and his Doctoral degree from Princeton University. He taught at the Catholic University of America in the Space Science and Applied Physics Department from 1966 to 1970. For NASA/GSFC and NOAA/NESS, Ken solved many orbit and attitude problems which required immediate attention. He was instrumental in solving various satellite navigation problems associated with TIROS-N and the first series of GOES satellites.


For the Navy, he formulated and developed an efficient Earth database structure for rapidly storing and retrieving high-resolution remotely-sensed global data. This formulation was based on the concept of a "Quadrilateralized Spherical Cube" (QLSC). For the Air Force, he has performed many leading-edge studies related to spacecraft collision probabilities. He is the author of the book Spacecraft Collision Probability published by AIAA in 2008. One of his algorithms has been adopted to estimate the lightning strike probability by the 45th Weather Squadron at the Kennedy Space Center and the Cape Canaveral Air Force Station. He also contributed to the book Multiscale Optimization Methods and Applications, published by Springer-Verlag in 2006. His chapter in this book on the simple criteria for the intersection of ellipsoids has been used in the simulation of the transport, collision and aggregation of blood cells in various types of blood flows.

OFFSITE EVENT – USS YORKTOWN

Tuesday, 31 January 6:15 - 9:00 pm Dinner and Ship Tour Location USS Yorktown

40 Patriots Point Road, Mount Pleasant, SC 29464 The USS Yorktown (CV-10) was the tenth aircraft carrier to serve in the United States Navy. The 888-foot Yorktown displaced 27,100 tons during World War II and carried a crew of 380 officers, 3,088 enlisted men, and an air group of 90 planes. She also served in the Vietnam War in the 1960s and recovered the Apollo 8 astronauts in 1968. Decommissioned two years later, the Yorktown was towed from New Jersey to Charleston in 1975 to become the centerpiece of Patriots Point Naval and Maritime Museum. Patriots point also offers a diesel powered submarine, “Clamagore”, and destroyer, “Laffey”. Vintage military aircraft and weapons are also on display. For more information, visit the Patriots Point website: http://www.patriotspoint.org. Docents will be available to give guided tours during the event, and there are also several marked self-guided tours. The flight simulator will be open for guests who wish to try its three simulations. A “Lowcountry style” buffet dinner will be served in the Hangar Bay area, with an open bar. The menu includes local deviled crabs, barbequed pulled pork, red rice, coleslaw, corn on the cob, green beans almondine, corn bread muffins, and banana pudding. Guests with any dietary restrictions should contact Matt Berry at [email protected] by January 20th so the caterer can be informed. All conference registrations will receive an event ticket. Adult guest tickets will be available prior to January 23, 2012 for $50 each. Tickets for children from 6-12 are available for $25. Children under 6 are free. Please contact the conference chairs if interested in guest tickets prior to January 23, 2011. Buses have been arranged to provide transportation to the Yorktown. Buses will be departing the hotel at 6:15 PM. Please meet in the hotel lobby prior to this time to board the buses.


CONFERENCE LOCATION

THE FRANCIS MARION HOTEL Francis Marion Hotel

387 King Street

Charleston, South Carolina 29403 USA

Phone: 1-843-722-0600

Fax: 1-843-853-2186

Toll-free: 1-877-756-2121

http://www.francismarionhotel.com

The Conference rate for the conference is $137 (100% of the current government per diem) plus applicable taxes.

Currently, the tax rate is 12.5% plus a $1.00 per room, per night destination fee. Please request the AAS/AIAA Space Flight Mechanics Meeting rate. The deadline for securing the conference rate at the hotel is January 9, 2012. The conference rate is valid for 3 nights before and after the conference dates, subject to availability. Complimentary internet access in guest rooms and meeting space is available to all conference attendees. Complimentary access to the hotel’s fitness center, located on the ground floor, is included for all guests.

TRANSPORTATION INFO The Charleston International Airport, www.chs-airport.com, is 12 miles from the Francis Marion hotel. The airport is served by multiple major carriers, and has direct flights from 15 locations. The airport has a negotiated rate with shuttle services to bring passengers to downtown hotels. The rate for these shuttles is $12 per person. These shuttles are located outside at the kiosk across from the Baggage Claim area of the airport. A private taxi costs approximately $26-30 to the downtown area. These are also available at the kiosk.

DRIVING DIRECTIONS

From Airport: Exit airport on International Drive and follow signs for I-526 to Mt. Pleasant From I-526 follow signs for I-26 East to Charleston. Travel on I-26 to the end (Meeting Street Exit) Turn right onto Meeting Street Stay on Meeting Street in the right hand lane for 0.6 miles Pass the Charleston Visitor’s Center and turn right at the light, which is John Street. Take John Street one block to King Street and turn left on King Street. The Francis Marion

Hotel is on the right.


From the North: I-95 South to I-26 East Follow Driving directions from Airport (3rd bullet)

From the South: I-95 North to US Hwy 17 North. Follow Hwy 17 (Savannah Hwy) North and cross the Ashley River Bridge. Hwy 17 will make a sharp turn to the left as it forks with Cannon Street. Follow the sign for

Cannon Street. Take Cannon Street until it ends at King Street. Turn right onto King Street. The Francis Marion is approximately 6 blocks on the right.

ARRIVAL INFORMATION

CheckIn and Checkout Check-in: 4:00 PM Check-out: 12:00 PM

Departure dates of each guest will be verified upon check-in. At that time, the guest may make adjustments to the actual departure date. After check-in, any individual attendee departing prior to their departure date will be charged an early departure fee of 50% of the room rate plus sales tax.

Parking Valet parking is available at a rate of $17.00 plus tax per night, automatically billed to your room. Self-parking is available in the City Garage located next to the hotel, at $12 per 24-hour period payable in cash to the garage attendant.

RESTAURANTS The following options are within a few blocks of the hotel. Please see the concierge desk for a complete list of local restaurants including more fine dining and upscale choices.

Hotel The Swamp Fox Restaurant and Bar. Classic southern flavor in a comfortable atmosphere. Starbucks Coffee Shop. Located at street level.

Quick and Casual Boone’s Bar & Grill, 345 King Street. Big menu of burgers, sandwiches & appetizers. King Street Grill, 304 King Street. Upscale sports grill with fabulous build your own salads. Closed for Business, 453 King Street. Great burgers, salads and sandwiches. O’Malley’s Bar & Grille, 549 King Street. Irish pub and sports bar with great tavern food.


Midtown Bar & Grill, 559 King Street. Southern casual cuisine with house smoked BBQ, burgers & wraps. HoM, 563 King Street. Burger boutique and ping pong lounge. Five Guys Burgers & Fries, 364 King Street.

MidRange Joe Pasta, 428 King Street. Pasta with you-pick-it sauces & toppings. Italian/American sandwiches, salads, appetizers. Sermet’s Corner, 276 King Street. Inventive Mediterranean dishes and wines. Basil Restaurant, 460 King Street. Refined Thai cuisine with only the finest ingredients. The Kickin’ Chicken, 350 King Street. Great sandwiches, salads, and such. Fried food at its best and buffalo wings too. Mellow Mushroom, 309 King Street. Gourmet pizzas, calzones, hoagies, and salads. Also, a large beer selection. Moe’s Southwest Grill, 381 King Street. Innovative Southwest/Mexican fare. Jim & Nick’s BBQ, 288 King Street. Pulled pork piled high. Sandwiches, burgers and salads. Juanita Greenberg’s Nacho Royale, 439 King Street. Mexican, with interesting twists. Monza, 451 King Street. Neapolitan style specializing in pizza, pastas & salads. Everything is made in house. 39 Rue De Jean, 39 John Street (one block to the left (North) exiting on King Street). French Bistro—great mussels & sushi bar. Fish, 422 King Street. Fresh local seafood served in an innovative fashion. Virginia’s, 412 King Street. Great Southern comfort fare. Coast, 39 John Street (one block to the left (North) exiting on King Street). Fresh seafood, with island flair! Tasty Thai & Sushi, 350 King Street. Spicy Thai food and full sushi bar. Chai’s Lounge & Tapas, 462 King Street. Fusion-style tapas in an awesome Asian-inspired space. Jestine’s Kitchen. 251 Meeting Street. Southern Home Cooking Il Cortiel del Re, 194A King Street. Northern Italian fare—very fresh and delicious!


Fine Dining / Upscale Charleston Grill, 224 King Street (Located in Charleston Place). World-class dining with imaginative cuisine. The Macintosh, 479B King Street. Upscale, hip atmosphere with exceptional locally inspired fare. La Fourchette, 432 King Street. Hearty French peasant food, wonderfully prepared. O-Ku, 463 King Street. Celebrates authentic traditional Japanese cuisine. Hall’s Chop House, 434 King Street. Prime steaks, lamb and veal chops, seafood specials and fancy Southern-inspired sides.

RECREATION The suggestions below are a partial list of the many things to do and see in Charleston. For more information and suggestions visit the concierge desk. The Charleston visitor’s bureau also has a very informative website: www.charlestoncvb.com/visitors/.

Tours Carriage and walking tours of Charleston are available from a variety of tour operators. In addition, many of the historic homes in Charleston offer tours. See the concierge or the visitor’s bureau website for a complete list of tour operators.

Attractions and Landmarks Fort Sumter/Spiritline Cruises, 360 Concord Street. (843) 881-7337. Departs daily from Liberty Square and Patriot’s Point. www.fortsumtertours.com. South Carolina Aquarium, 100 Aquarium Warf. (843) 720-1990, www.scaquarium.org. Drayton Hall, 3380 Ashley River Road, West Ashley. (843) 769-2600, www.DraytonHall.org. Middleton Place, 4300 Ashley River Road, West Ashley. (843) 556-6020, www.middletonplace.org. Old Exchange Building and Provost Dungeon, 122 East Bay Street. (843) 727-2165. 300 years of pirates, patriots, presidents, and preservation. www.oldexchange.com. Boone Hall Plantation, 1235 Long Point Road, Mt. Pleasant. (843)884-4371, www.boonehallplantation.com. Magnolia Plantation and Gardens, 3550 Ashley River Road, West Ashley. (843)571-1266, www.magnoliaplantation.com. Battery Park / White Point Gardens. Located at the southern point of the Charleston peninsula, the park features a display of civil war cannons and offers views of Charleston Harbor and Fort Sumter.


Museums Charleston Museum, 360 Meeting Street. (843)722-2996. America’s First and Oldest Museum. www.charlestonmuseum.org. Gibbes Museum of Art, 135 Meeting Street. (843)722-2706. Features one of the finest collections of American art in the southeast. www.gibbesmuseum.org. Children’s Museum of the Lowcountry, 25 Ann Street. (843) 853-8962. www.explorecml.org. Four blocks from the hotel. Features an art room, pirate ship, castle, and more.

Shopping City Market, Meeting and Market Streets. Traditionally open 9am-5pm daily. Gift Shops, Souvenir Shops, Eateries, and Bars on the North and South Market sides. Upper King Street. Upscale Boutique Shopping. Lower King Street. Popular Chain Stores & Small Boutiques. Tanger Outlet Center (North Charleston), 4840 Tanger Outlet Blvd. (843) 529-3095.

Golf Patriots Point Links, 1 Patriots Point Road, Mount Pleasant. 843-881-0042, www.patriotspointlinks.com. Wild Dunes Resort Golf, 5757 Palm Blvd, Isle of Palms. (843) 886-2164, www.wilddunes.com.


AREA MAP Additional maps are located at www.charlestoncvb.com/visitors/travel_support/maps.html.


ADDITIONAL INFORMATION

SPEAKER ORIENTATION On the day of their sessions, authors making presentations meet with their session chairs at 7:00 am. Breakfast will be served. Check the schedule at the beginning of the program for the location of the speaker’s breakfast each morning. Speaker attendance is mandatory.

VOLUNTEERS Volunteers that would like to staff the registration table may sign up at the registration table.

PRESENTATIONS Each presentation is limited to 20 minutes. An additional five minutes is allotted between presentations for audience participation and transition. Session chairs shall maintain the posted schedule to allow attendees the option of joining a parallel session. Each room is equipped with a laser pointer, an electrical outlet, and a video projector that can be driven by a computer. Presenters shall coordinate with their Session Chairs regarding the computing equipment, software, and media requirements for the session; however, each presenter is ultimately responsible for having the necessary computer and software available to drive the presentation. Microsoft PowerPoint and PDF are the most common formats.

"No-Paper, No-Podium" Policy Completed manuscripts shall be electronically uploaded to the submission site before the conference, limited to 20 pages in length, and conform to the AAS conference paper format. If the completed manuscript is not contributed on time, it will not be presented at the conference. If there is no conference presentation by an author, the contributed manuscript shall be withdrawn.

PREPRINTED MANUSCRIPTS Physical copies of preprinted manuscripts are no longer available or required for the Space Flight Mechanics Meetings or the Astrodynamics Specialist Conferences. Electronic preprints are available for download at least 72 hours before the conference at https://aas.pxi.com/registration/reg/ for registrants who use the online registration system. The hotel provides conference guests with complimentary wireless internet access in guest rooms and the conference meeting space. Registrants without an internet-capable portable computer, or those desiring traditional paper copies should download and print preprint manuscripts before arriving at the conference.

CONFERENCE PROCEEDINGS All full registrants will receive a CD of the proceedings mailed to them after the conference (extra copies are available for $45 during the conference). However, the hardbound volume of Advances in the Astronautical Sciences covering this conference will be available to attendees at a reduced pre-publication cost, if ordered at the registration desk. After the conference, the hardbound proceedings will more than double in price, although authors will still receive a special 50% discount off the post-conference rate even if they delay their order until after the conference. Cost of Proceedings:


Conference Rate $250 domestic ($300 international) Post-Conference Rate $520 (approx.) Authors (post-conference) $260 (approx.)

Although the availability of hardcopy proceedings enhances the longevity of your work and elevates the importance of your conference contribution, please note that conference proceedings are not considered an archival publication. Authors are encouraged to submit their manuscripts after the meeting to one of the relevant journals, such as:

Journal of Guidance, Control and Dynamics Editor-in-Chief: George T. Schmidt, Massachusetts Institute of Technology Manuscripts can be submitted via: www.writetrack.net/aiaa/

Journal of Spacecraft and Rockets Editor-in-Chief: E. Vincent Zoby, NASA Langley Research Center Manuscripts can be submitted via: www.writetrack.net/aiaa/

Journal of the Astronautical Sciences Editor-in-Chief: Kathleen C. Howell School of Aeronautics and Astronautics 3233 Armstrong Hall Purdue University West Lafayette, IN 47907 (765) 494-5786 [email protected]

SATISFACTION SURVEY Registrants are highly encouraged to record their level of satisfaction and conference preferences in an anonymous survey taken throughout the time of the conference. Please return the survey form included in this program to the registration table before departing from the conference.

COMMITTEE MEETINGS Committee seating is limited to committee members and invited guests. Committee and subcommittee meetings will be held according to the schedule at the beginning of the program.


Jan 30, 2012 Carolina A

Session 1: Formation Flying I

Chair: Dr. Aaron Trask, Apogee Integration 08:00 AAS 12 - 100 Early Formation Design using a Geometrical Approach

Jason Tichy, a.i. solutions, Inc.

High-fidelity spacecraft formation design requires numerical integration of ordinary differential equations that incorporate perturbations from atmospheric drag, solar radiation pressure, other celestial bodies, as well as effects from a non-spherical Earth. Numerically based optimization algorithms are often required to develop solutions that are consistent with these perturbations, and incremental improvements to model fidelity generates little insight into the overall design space within the context of mission feasibility and requirements. A new method for formation design, based on geometrical Keplerian ellipses, is introduced to facilitate the understanding of the design space and alleviate numerical complexity.

08:25 AAS 12 - 101 Effects of Staggering Formation Maneuvers on the Magnetospheric MultiScale (MMS) Mission Trajectories Khashayar Parsay and Laurie Mann, a.i. solutions, Inc.; Trevor Williams, NASA Goddard Space Flight Center

To execute a formation maneuver during the MMS mission, each spacecraft employs a two-burn transfer to achieve its desired state. Because of communication limitations, only one spacecraft can fire its thrusters at any given time. Therefore, the maneuvers are staggered 75 minutes apart resulting in having two maneuver sets, one that includes all the first maneuvers and one that includes all the second maneuvers. The selection of the staggering sequence has a significant impact on the fuel and the spacecraft close approach profile. This paper examines this impact for Phase I of the mission.

08:50 AAS 12 - 102 Formation Maneuver Planning for Collision Avoidance and Direction Coverage Liam M. Healy and C. Glen Henshaw, Naval Research Laboratory

We develop techniques for determining the maneuvers needed to keep an inspector vehicle close to the host without colliding while being able to inspect the desired faces of the host. We use apocentral coordinates and the geometric relative orbital elements developed earlier. We separate change in relative velocity (maneuvers) into radial and cross-track components and use a waypoint technique to plan the maneuvers. By considering maneuvers that only preserve the relative orbital plane and those that only change the cross-track component of relative velocity, we simplify maneuver planning while maintaining passive safety.

09:15 AAS 12 - 103 A Lyapunov-Floquet Generalization of the Hill-Clohessy-Wiltshire Equations Ryan E. Sherrill and Andrew J. Sinclair, Auburn University; T. Alan Lovell, Air Force Research Laboratory

The relative motion between chief and deputy satellites in close proximity in orbits of arbitrary eccentricity can be described by linearized time-varying equations of motion. The linear time-invariant Hill-Clohessy-Wiltshire equations are typically derived from these equations by assuming the chief satellite is in a circular orbit. However, a Lyapunov-Floquet transformation relates the linearized equations of relative motion to the Hill-Clohessy-Wiltshire equations through a periodic coordinate transformation without requiring an eccentricity assumption. This transformation is based on the invariant form of the Tschauner-Hempel equations, and evaluates the Hill-Clohessy-Wiltshire equations at a virtual time.


09:40 Break

10:05 AAS 12 - 104 Optimal Reconfigurations of Coulomb Formations along Invariant Manifolds Drew R. Jones, The University of Texas at Austin

Coulomb formations actively control the electrostatic charges of closely-flying spacecraft, enabling relative motion control that is essentially propellant-less. The dynamics of these formations, including natural motions about known equilibrium configurations is discussed. Invariant manifold theory and Particle Swarm Optimization are proposed as novel tools in the numerical determination of unknown equilibrium conditions and optimal reconfigurations between known equilibrium states. A generalized methodology is outlined, to exploit uncontrolled motion along manifolds, for optimizing transfers between Coulomb configurations. The generalized method is then tested using a 2-craft Coulomb formation model with linearized 2-body gravity, and simple but physically representative control models.

10:30 AAS 12 - 105 Effective Coulomb Force Modeling in a Space Environment Laura A. Stiles, Carl R. Seubert, and Hanspeter Schaub, University of Colorado at Boulder

Coulomb formation flight is an emerging concept that utilizes electrostatic forces to maintain a formation of close proximity spacecraft. This paper explores to what extent the plasma environment affects the magnitude of the Coulomb force. This is achieved through the use of analytic models that bound the extent of Coulomb forces as well as fitting an effective Debye length to numerical solutions to more accurately, yet still efficiently, calculate the force. Effective Debye lengths at GEO and LEO conditions are examined and are found to be significantly larger. These results increase feasibility of Coulomb applications in dense LEO plasmas.

10:55 AAS 12 - 106 Multi-Sphere Modeling for Electrostatic Forces on Three-Dimensional Spacecraft Shapes Daan Stevenson and Hanspeter Schaub, University of Colorado at Boulder

The use of electrostatic (Coulomb) actuation is attractive for formation flying, but current analytical electrostatic force models do not capture any orientation dependent forces or torques on generic spacecraft geometries as encountered during very close operations. The Multi Sphere Model (MSM) uses a collection of finite spheres to represent a complex shape and analytically approximate the Coulomb interaction with other charged bodies. Using the MSM, six degree of freedom electrostatic simulations of relative spacecraft motion are possible in real time, which is crucial for the development of robust relative position and orientation control algorithms in local space situational awareness applications.

11:20 AAS 12 - 107 Analysis on Spacecraft Formation Flying in Elliptic Reference Orbits Jonghee Bae and Youdan Kim, Seoul National University

Formation analysis is performed for the periodic relative motion between two spacecraft in Keplerian elliptic orbits. While the relative motion in the circular orbit has an ellipse in the in-plane, the follower spacecraft in the elliptical orbit does not have an ellipse of fixed eccentricity due to the eccentricity of the reference orbit. In this study, the spacecraft formation flying is analyzed and the instantaneous eccentricity of the relative motion is derived to describe the natural periodic relative motion. Numerical simulations are demonstrate the formation trajectories, and finally the desired constraints are provided for the formation design.


11:45 AAS 12 - 108 Comparison and Application Analysis of Classical Relative Motion Models Jianfeng Yin and Chao Han, Beihang University

In this paper several classical relative motion models are compared for a wide variety of conditions. The accuracy and applicability of these models are analyzed. The models involved in this investigation are the familiar Hill’s equations, Lawden’s equations, Alfriend’s geometric method, a new model based on a new set of relative orbit elements and a numerical propagator. The effects of variations of orbital parameters, orbit types, the relative orbit size and the reference orbit eccentricity are analyzed. The four relative model’s capability of formation design is also researched. The proposed method and conclusions are validated through numerical examples.


Jan 30, 2012 Carolina B

Session 2: Space Situational Awareness

Chair: John Seago, Analytical Graphics, Inc. 08:00 AAS 12 - 109 Agile RSO Attitude Estimation Using Lightcurve Inversion and Bayesian

Estimation with Shape Model Uncertainty Marcus J. Holzinger and Kyle T. Alfriend, Texas A&M University; Charles J. Wetterer and Kris Hamada, Pacific Defense Solutions, LLC; K. Kim Luu and Chris Sabol, Air Force Research Laboratory; Andrew Harms, Princeton University

The problem of estimating attitude for actively maneuvering or tumbling Resident Space Objects (RSOs) with unknown mass properties / external torques and uncertain shape models is addressed. Exponentially Correlated Acceleration (ECA) approaches from manned aircraft tracking are applied to the attitude dynamics, and model uncertainty is accounted for in a bias state with dynamics derived using first-principles. Bayesian estimation approaches are suggested as a means by which severely non-Gaussian and multi-model state distributions may be properly captured. Simulated results are given, conclusions regarding performance are made, and future work is outlined.

08:25 AAS 12 - 110 Delta-V Distance Object Correlation and Maneuver Detection with Dynamics Parameter Uncertainty and Generalized Constraints Marcus J. Holzinger and Kyle T. Alfriend, Texas A&M University; Daniel J. Scheeres, University of Colorado at Boulder

Correlating observations with one another or with known objects as well as detecting and characterizing maneuvers is examined. A survey of existing observation correlation and maneuver detection techniques is given, and potential shortcomings for maneuver spacecraft identified. Existing optimal control correlation and maneuver detection methods are extended to accommodate arbitrary numbers of general intermediate state constraints and associated distributions, as well as dynamics parameter uncertainty. Simulated results are reviewed, and conslusions and future work are outlined.

08:50 AAS 12 - 111 Utilizing Stability Metrics to Aid in Sensor Network Management Solutions for Satellite Tracking Problems P.S. Williams and D.B. Spencer, The Pennsylvania State University; R.S. Erwin, Air Force Research Laboratory

The following work examines how measuring the stability of satellite dynamics through calculation of Lyapunov exponents can be utilized to help create sensor tasking decisions for a multi-object, multi-sensor satellite tracking problem. These methods willbe applied to a simulation which attempts to represent a simplified tracking component of the Space Situational Awareness problem with one hundred simulated satellites and five sensors. Results from various simulations will be analyzed in order to determine the possible effectiveness of such methods to reduce the overall uncertainty of all tracked objects, aiding in the effectiveness in detecting possible in-space collisions.


09:15 AAS 12 - 112 Comparison of Two Single-Step, Myopic Sensor Management Decision Processes Applied to Space Situational Awareness P.S. Williams and D.B. Spencer, The Pennsylvania State University; R.S. Erwin, Air Force Research Laboratory

The following work describes a sensor tasking approach for a multi-object, multi-sensor tracking problem analogous to the monitoring of resident space objects known as Space Situational Awareness (SSA). To conduct this tasking, two information theory-based utility metrics are implemented in order to task sensors to observe satellites which will maximize the total information gained at discrete simulation time-steps. Using a simple simulation of the nonlinear estimation and tasking components of the SSA problem, comparisons will be made between combinations of tasking and estimators in regards to their impact on overall tracking performance.

09:40 Break

10:05 AAS 12 - 113 Co-Orbiting Anti-Satellite Vulnerability Salvatore Alfano, Center for Space Standards and Innovation

This work uses simple orbital dynamics to initially assess the vulnerability of a satellite to a Space-Based Interceptor (SBI) launched from an orbiting, anti-satellite, carrier platform. The method produces an engagement volume derived from the position and velocity vectors of the launching platform, the range of impulsive velocities that can be imparted to the SBI upon deployment, and the maximum expected time-of-flight from release until intercept. If a satellite is likely to pass through the volume, then it is considered vulnerable although the SBI would have launched much earlier.

10:30 AAS 12 - 115 Inverse Problem Formulation Coupled with Unscented Kalman Filtering for State and Shape Estimation of Space Objects Laura Henderson, Pulkit Goyal and Kamesh Subbarao, The University of Texas at Arlington

Given time series astromeric and photometric measurements from the Space Survilance Network (SSN) as explicit and implicit functions of position, attitude, and resident space object's (RSO) shape and size, in addition to governing equations for the system dynamics and appropriate measurement models the following problem will be solved. Combined Direct + Inverse Problem: This problem aims to determine the position, velocity, angular velocity, attitude and the RSO's shape and size. The parameters are estimated using a maximum likelihood approach and integrated into the UKF. The results of this hybrid algorithm are then compared with the joint state/parameter estimation technique.

10:55 AAS 12 - 116 Small Satellite Missions for Debris Tracking and Mitigation Joseph W. Gangestad, Sarah A. Whalley, Glenn E. Peterson and Thomas J. Lang, The Aerospace Corporation

Results are presented from a study into the feasibility of small satellites, such as CubeSats, to perform proximity operations near potentially hazardous space debris and to provide higher precision tracking measurements than available from ground-based assets. Candidate orbital communications relays for the CubeSats were identified along with their associated link and coverage statistics, the performance of optical ranging systems were considered relative to the estimated reflectivity of spacecraft materials, and propellant requirements were estimated for non-cooperative formation-keeping between the CubeSat and a debris target.


11:20 AAS 12 - 117 Inactive Space Object Shape Estimation via Astrometric and Photometric Data Fusion Richard Linares and John L.Crassidis, University at Buffalo

This paper presents methods to determine the shape of a space object in orbit while simultaneously recovering the observed space object's inertial orientation and trajectory. The filter employs the Unscented estimation approach, reducing passively-collected electro-optical data to infer the unknown state vector comprised of the space object inertial-to-body orientation, position and their respective temporal rates. Recovering these characteristics and trajectories with sufficient accuracy is shown in this paper. The performance of this strategy is demonstrated via simulated scenarios.


Jan 30, 2012 Calhoun

Session 3: Attitude Determination

Chair: Dr. Sergei Tanygin, Analytical Graphics, Inc. 8:00 AAS 12 - 118 Filtering Solution to Relative Attitude Determination Problem Using Multiple

Constraints Richard Linares and John Crassidis, University at Buffalo; Yang Cheng, Mississippi State University

In this paper a relative attitude filtering solution of a formation of two vehicles with multiple constraints and gyro measurements is shown. The solution for the relative attitude between the two vehicles is obtained only using line-of-sight measurements between them and a common (unknown) object observed by both vehicles. The constraint used in the solution is a triangle constraint on the vector observations and gyro mesurements. This approach is extended to multiple objects by apply this constraint for each object. Simulation runs to study the performance of the approach will be shown.

08:25 AAS 12 - 119 Complete Closed Form Solution of a Tumbling Triaxial Satellite under Gravity-Gradient Torque Martin Lara and Sebastian Ferrer, University of Murcia

We revisit the attitude dynamics of a tumbling triaxial satellite under gravity-gradient. The total reduction of the Euler-Poinsot Hamiltonian provides a suitable set of canonical variables that expedite the perturbation approach. Two canonical transformations reduce the perturbed problem to its secular terms. The secular Hamiltonian and the transformation equations of the averaging are computed in closed form of the triaxiality coefficient, thus being valid for any triaxial body. The solution depends on Jacobi elliptic functions and integrals, and is valid for non-resonant rotations under the assumption that the tumbling rate is much higher than the orbital or precessional motion.

08:50 AAS 12 - 120 Cayley Attitude Technique John E. Hurtado, Texas A&M University

Single point attitude determination is the problem of estimating the instantaneous attitude of a rigid body from a collection of vector observations taken at a single moment in time. Many methods have been proposed to solve this problem, most of which are based on Wahba's problem. Here, a new technique is presented that uses a generalized Cayley transform. Algorithms to optimally solve the attitude estimation problem for a wide family of attitude parameters are given.

09:15 AAS 12 - 121 Attitude Estimation in Higher Dimensions John E. Hurtado, Texas A&M University

To date, there has been only one archival journal paper devoted to attitude determination in dimensions higher than three. A review of literature reveals, however, that the kinematics, kinetics, and control of bodies that occupy abstract higher dimensional spaces has been extensively investigated. Many of those studies tell of a relevant connection between real physical systems in three dimensions and a counterpart in higher dimensions. Therefore, it is with similar hopes in mind that the problem of single instance attitude estimation for bodies in abstract higher dimensional spaces is reviewed.

09:40 Break


10:05 AAS 12 - 122 Linear Solutions to Single Instance Position and Attitude Estimation John E. Hurtado, Texas A&M University

The combined attitude and position estimation problem has received less attention than the attitude-only problem. Here, new developments are presented for this problem that use a generalized Cayley transform. One interesting viewpoint involves casting the position and attitude in three dimensions as an attitude-only problem in four dimensions.

10:30 AAS 12 - 123 Analysis and Comparison of Rate Estimation Algorithms Using Coarse Sun Sensors and a Three-Axis Magnetometer Tae W. Lim, United States Naval Academy; Frederick A. Tasker, Naval Research Laboratory

This paper examines various rate estimation approaches using sun vector and earth magnetic field B-vector measurements, either individually or collaboratively, for safehold design applications. Three possible approaches of estimating body rates using coarse sun sensors (CSS's) and a three axis magnetometer (TAM) are presented in detail including sun vector only (or CSS only) approach, magnetic field vector only (or TAM only) approach, and combined sun vector and magnetic field vector approach. Using simulations and flight operations experiences the paper discusses their advantages and disadvantages to help design a safehold mode that will meet the design requirements most effectively.

10:55 AAS 12 - 124 Autonomous Spacecraft Attitude Resource Sharing Shawn C. Johnson and Norman G. FItz-Coy, University of Florida; Seth L. Lacy, Air Force Research Laboratory

This paper investigates the use of attitude sharing between two satellites. The first, sharing, satellite, has inertial and relative attitude sensors. The second, receiving, satellite can only propagate attitude. Relative attitude is available only under certain alignment conditions consistent with proper orientation of a relative attitude sensor on the sharing satellite and attitude fiducials on the receiving satellite. An uncertainty-based metric is derived from the Extended Kalman Filter, as an autonomous switching condition for resource sharing. Simulation results indicate that one star tracker can accommodate the pointing requirements for multiple spacecraft, with performance advantages over a fixed-measurement schedule.

11:20 AAS 12 - 125 Novel Multiplicative Unscented Kalman Filter for Attitude Estimation Renato Zanetti, The Charles Stark Draper Laboratory; Kyle J. DeMars, Air Force Research Laboratory; Daniele Mortari, Texas A&M University

A novel spacecraft attitude estimation algorithm is presented. The new algorithm utilizes unit vector measurements and is based on the unscented Kalman filter (UKF). The UKF, like the extended Kalman filter, employs a linear update in which an additive residual is formed. The residual is given by the difference between the measurement and its mean. This work utilizes a multiplicative residual in which the measurement and the mean are multiplied together using the vector cross product. Because of the nature of the problem a multiplicative residual combined with a multiplicative update is a more natural solution.


11:45 AAS 12 - 126 Projective Geometry of Attitude Parameterizations with Applications to Control and Tracking Sergei Tanygin, Analytical Graphics, Inc.

Vectorial attitude parameterizations can be viewed as projections from the unit quaternion hypersphere onto a hyperplane tangential to the hypersphere at a point representing zero rotation. It is shown that, if the projection hyperplane is moved to any other point on the hypersphere, the resulting parameterization and its kinematics follow directly from the formulations that are well-known in attitude tracking problems. It is also shown how a generalization of stereographic projection geometry can support various attitude parameters, and how one particular stereographic projection can efficiently and accurately approximate the rotation vector parameterization for a full range of rotation angles.



Session 4: Asteroid and Near-Earth Object Missions I

Chair: Kenneth Williams, KinetX, Inc. 13:30 AAS 12 - 127 Earth Delivery of a Small NEO with an Ion Beam Shepherd

Claudio Bombardelli, Hodei Urrutxua and Jesus Pelaez, Technical University of Madrid

The possibility of capturing a small Near Earth Asteroid (NEA) and deliver it to the vicinity of the Earth has been recently explored by different authors. Among the different challenges related to this operation stands the difficulty of robotically capturing the object, whose composition and dynamical state could be problematic. In order to simplify the capture operation we propose the use of a collimated ion beam ejected from a hovering spacecraft in order to maneuver the object without direct physical contact. The feasibility of this approach and the mass cost of a possible asteroid retrieval mission is evaluated.

13:55 AAS 12 - 128 Conceptual Design of Planetary Defense Technology Demonstration Mission Alan Pitz, George Vardaxis and Bong Wie, Iowa State University

When the lead time of the probable impacting NEO is short, nuclear explosives delivered by an innovative design of a versatile, two-body hypervelocity nuclear interceptor spacecraft (HNIS) may be mandated to safeguard the Earth. With the current survival limitations of nuclear triggering systems, flight demonstrations are mandatory to validate viable HNIS concepts, terminal guidance instruments and sensors, thermal shielding on the follower spacecraft, and mission operations. Considering three different budget constraints ($250M, $500M, and $1B), conceptual mission designs to a target NEO are created using AGI’s Satellite Tool Kit, NASA’s General Mission Analysis Tool, and ADRC's mission analysis software.

14:20 AAS 12 - 129 Design of Spacecraft Missions to Test Kinetic Impact for Asteroid Deflection Sonia Hernandez, The University of Texas at Austin; Brent Barbee, NASA Goddard Space Flight Center

Earth has previously been struck with devastating force by near-Earth asteroids (NEAs) and will be struck again. Telescopic search programs aim to provide advance warning of such an impact, but no techniques or systems have yet been tested for deflecting an incoming NEA. To begin addressing this problem, we have analyzed the more than 8000 currently known NEAs to identify those that offer opportunities for safe and meaningful near-term tests of the proposed kinetic impact asteroid deflection technique. In this paper we present our methodology and results, including complete mission designs for the best kinetic impactor test mission opportunities.

14:45 AAS 12 - 130 Feedback Stabilization of Displaced Periodic Orbits: Application to Binary Asteroid Jules Simo and Colin R. McInnes, University of Strathclyde

This paper investigates displaced periodic orbits at linear order in the circular restricted Earth-Moon system (CRTBP), where the third massless body utilizes a hybrid of solar sail and a solar electric propulsion (SEP). Attention is now directed to binary asteroid systems as an application of the restricted problem. The idea of combining a solar sail with an SEP auxiliary system to obtain a hybrid sail system is important especially due to the challenges of performing complex trajectories.


15:10 Break

15:35 AAS 12 - 131 Dynamical Characterization of 1:1 Resonance Crossing Trajectories at Vesta Alex Haro, Universitat de Barcelona; Josep-Maria Mondelo, Universitat Autonoma de Barcelona; Benjamin F. Villac, University of California at Irvine

Motivated by the challenges associated with the 30-days transfer of the 1:1 resonance crossing of the Dawn mission, which entered its high-altitude mapping orbit on 29 September 2011, this paper analyzes the dynamical structure and sensitivity of 1:1 resonance crossing ballistic transfers at Vesta. In particular, a combination of chaoticity maps with frequency analysis and invariant object continuations is proposed to provide the necessary support for design and analysis risk mitigation strategies in these regions.

16:00 AAS 12 - 132 Close Proximity Asteroid Operations Using Sliding Control Modes Roberto Furfaro, University of Arizona; Dario O. Cersosimo, University of Missouri at Columbia; Julie Bellerose, Carnegie Mellon University Silicon Valley / NASA Ames Research Center

Close proximity operations around small celestial bodies are extremely challenging due to their uncertain dynamical environment. In this paper, we show that the Multiple Sliding Surface Guidance (MSSG) algorithm, already proposed for autonomous asteroid pin-point guidance, can be extended to guide the transition of the spacecraft from any two desired states, including hovering and orbital states. Constructed using two sliding surfaces, the algorithm takes advantage of the system’s ability to reach the sliding surfaces in finite time. The algorithm does not require either ground-based or on-board trajectory generation but computes an acceleration command that target a specified state.

16:25 AAS 12 - 133 Fourth-order Gravity Gradient Torque of Spacecraft Orbiting Asteroids Yue Wang and Shijie Xu, Beihang University

To improve previous fourth-order model, a full fourth-order gravity gradient torque model of a rigid spacecraft around an asteroid with a 2nd degree and order-gravity field is established by introducing spacecraft’s higher-order inertia integrals. A numerical simulation is carried out to verify our model using a special rigid body consisted of 36 point masses moving on the synchronous orbit. Simulation results show that the motion of previous fourth-order model is quite different from the exact motion, while our full fourth-order model fits exact motion very well, and our model is precise enough for practical applications.

16:50 AAS 12 - 134 On the Planar Motion in the Full Two-Body Problem Pamela Woo and Arun K. Misra, McGill University

The motion of binary asteroids, modeled as the full two-body problem, is studied. The shape and mass distribution of the bodies are considered. Using the Lagrangian approach, the equations governing the planar motion are derived. The resulting system of four equations are nonlinear and coupled. In the particular case where the bodies are axisymmetric around an axis normal to the plane, the system reduces to a single equation, with small nonlinearity. The method of multiple scales is used to obtain a first-order solution. This is proven to be sufficient when compared with the numerical solution.



Session 5: Dynamical Systems Theory I

Chair: Dr. Robert Melton, Pennsylvania State University 13:30 AAS 12 - 135 Invariant Manifolds to Design Scientific Operative Orbits in the Pluto-Charon

Binary System Davide Guzzetti and Michele Lavagna, Politecnico di Milano

Feasibility of operative orbits in the Pluto-Charon system has been investigated in this work. Given that currently only the New Horizon NASA mission will perform a quick fly-by of Pluto-Charon, the chance to close a spacecraft in orbit around the system would represent a significant add-on in the science knowledge domain and an interesting challenge from the flight dynamics perspective. A R3BP coupled with the invariant manifolds are the main tools here exploited to manage the trajectories design; itineraries and strategies, that can meet the requirements of costs minimization, long operative life and adequate coverage of the surfaces, are proposed.

13:55 AAS 12 - 136 Approaching Moons from Resonance via Invariant Manifolds Rodney L. Anderson, Jet Propulsion Laboratory

In this work, the approach phase from the final resonance of the endgame scenario in a tour design is examined within the context of invariant manifolds. Previous analyses have typically solved this problem either by using numerical techniques or by computing a catalog of suitable trajectories. The invariant manifolds of a selected set of libration orbits and unstable orbits are computed here to serve as guides for desirable approach trajectories. The analysis focuses on designing the approach phase sothat it ties in with the final resonance in the endgame sequence while also targeting desired conditions at the moon.

14:20 AAS 12 - 137 Attainable Sets in Space Mission Design: A Method to Define Low-Thrust, Invariant Manifold Trajectories Giorgio Mingotti, Technion – Israel Institute of Technology; Francesco Topputo and Franco Bernelli-Zazzera, Politecnico di Milano

A method to incorporate low-thrust propulsion into the invariant manifolds technique for space trajectory design is presented in this paper. Low-thrust propulsion is introduced by means of attainable sets that are used in conjunction with invariant manifolds to define first guess solutions in the restricted-three body problem. They are optimized in the restricted four-body problem where an optimal control problem is formalized. Several missions are investigated in the Earth--Moon system: transfers to libration point orbits and to periodic orbits around the Moon. Attainable sets allow the immediate design of efficient complex space trajectories.


14:45 AAS 12 - 138 Efficient Trajectory Correction for L2 Halo-Orbit Transfer using Stable Manifolds Yoshihide Sugimoto and Triwanto Shimanjuntak, The Graduate University for Advanced Studies; Masaki Nakamiya and Yasuhiro Kawakatsu, Japan Aerospace Exploration Agency

Halo orbit around Lagrange point (L point), especially at L2 point, is recently in the spotlight because of its periodicity, suitable location for deep-space astronomical observations, and stable thermal environment. In near future, several missions like technical demonstration and observation missions will be launched to utilize a Halo orbit. Stable manifolds, which are constructed by dynamical system theory, are strong feature to insert the spacecraft naturally into a Halo orbit. In this paper, we show stable manifolds prediction first using a scaling method and then an efficient trajectory correction method by means of predicted stable manifolds in the Circular Restricted Three-Body Problem.

15:10 Break

15:35 AAS 12 - 139 Discrete-Time Bilinear Representation of Continuous-Time Bilinear State-Space Models Minh Q. Phan, Dartmouth College; Yunde Shi, Raimondo Betti and Richard W. Longman, Columbia University

This paper develops techniques to represent a first-order continuous-time bilinear state-space model by various first-order discrete-time bilinear state-space models. Although it is generally possible to discretize any well-behaved continuous-time model, presented are techniques that keep the discrete-time bilinear model in first-order form while maintaining the simple bilinear structure of the original continuous-time model. A class of techniques based on Adams-Bashforth integration methods is found to meet these requirements, whereas simpler Euler methods produce unstable discrete-time models. Application of the developed techniques to derive discrete-time bilinear models of satellite attitude dynamics is presented.

16:00 AAS 12 - 140 Expanding Transfer Representations in Symbolic Dynamics for Automated Trajectory Design Eric Trumbauer and Benjamin Villac, University of California at Irvine

Previous studies have shown symbolic dynamics can be used to find transfers with desirable global transit characteristics using libration point region and manifold structures in the CR3BP. However, this method cannot control for practical orbital elementssuch as altitude and inclination. Extensions of existing symbolic dynamic methods are needed for automated selection of trajectories with these attributes. Enabling this are recent studies which have shown connections between important classical characteristics and structures such as resonant orbits, collision trajectories, and manifolds. This paper analyzes the utility of such an extension in the planar problem as a first step in this direction.

16:25 AAS 12 - 142 A Theory of Low Eccentricity Satellite Motion William E. Wiesel, Air Force Institute of Technology

Earth satellite motion is considered from the point of view of periodic orbits and Floquet theory in the earth's zonal potential field. Periodic orbits in the zonal potential are nearly circular, except near the critical inclination. Since the earth's oblateness is included in the periodic orbit, perturbations generally begin at one part in a hundred thousand, not one part in a thousand. Perturbations to the periodic orbit are calculated for sectoral and tesseral potential terms, for air drag, and for third body effects. There results a compact, purely numerical set of algorithms that may be quite accurate.


16:50 AAS 12 - 143 Two-Point Boundary Value Problem of the Relative Motion Hao Zhang, Zhao Yushan, Shi Peng and Li Baojun, Beihang University

The two-point boundary value problem of relative motion is studied both in the frameworks of relative motion theory and relative Lambert’s problem theory. It is shown that the solutions obtained by the above two methods are equivalent to the first order. Singularity occurs when linearization is used in both methods. It is proved that the singularity is also equivalent. Singularity is then studied in the point of view of multiple-revolution Lambert’s problem. Further analysis shows that whether the singularity can happen or not depend on the boundary values. Several examples are given to illustrate the findings.



Session 6: Formation Flying II

Chair: Dr. Matthew Wilkins, Schafer Corporation 13:30 AAS 12 - 144 Circular Lattice String-of-Pearls Constellations for Radio Occultation Mission

Sanghyun Lee and Daniele Mortari, Texas A&M University

This paper addresses the problem of designing suitable satellite constellation for Radio Occultation mission. Radio occultation for Earth atmosphere usually requires global coverage and short interval measurements. The Circular (2-D) Lattice Flower Constellation theory is here applied to design constellations maximizing active time with providing global coverage and frequent measurements. Optimizations are performed using Genetic Algorithms to estimate constellation design parameters. Optimization is constrained by altitude range (drag and Van Allen belt avoidance) and nodal precession is used to obtain global coverage. The performance of some solutions are provided to help optimality selection.

13:55 AAS 12 - 145 Common-Period Four-Satellite Continuous Global Coverage Constellations Revisited John E. Draim, Consultant; Weijung Huang, University of Missouri at Columbia; David A. Vallado and David Finkleman, Center for Space Standards and Innovation; Paul J. Cefola, Consultant in Aerospace Systems

Global constellation coverage has been a topic of interest for many years. The Draim four-satellite continuous global coverage constellation has significant improvement over traditional coverage constellations. We re-look at this constellation using new analytical search techniques, computational methods to assess the dynamic performance, and graph-ical depictions. Using the original orbits, we vary orbital parameters to determine how the constellation reacts to additional constraints. Evaluation criteria are expanded to include the number of satellites, distance from the earth, orbital regimes, conjunction probabilities, communication link margins, etc. Technical statistics of satellite access parameters and graphical depictions are also examined.

14:20 AAS 12 - 146 Optimization of Hybrid Orbit Constellation Design for Space-Based Surveillance System Hongzheng Cui, Xiucong Sun and Chao Han, Beihang University

The focus for this paper is to design the satellite constellation to observe GEO regime, and HEO, SubGEO, and hybrid orbit with both HEO and SubGEO are adopted as mission orbits for Space-Based Surveillance System (SBSS). A new method called the rapid method for satellite constellation performance calculation is developed by the Hermite interpolation technique to reduce the computing complication and time. The SBSS constellation optimization models are presented and the evolutionary algorithm is adopted to optimize the configuration parameters.


14:45 AAS 12 - 147 Reducing Walker, Flower, and Streets-of-Coverage Constellations to a Single Constellation Design Framework Jeremy J. Davis, VectorNav Technologies, LLC; Daniele Mortari, Texas A&M University

Satellite constellations are typically designed using either Walker or streets-of-coverage methods. In some cases, the constellation may be optimized on the individual satellite level to produce non-uniform distributions. The recently developed lattice theory of Flower Constellations has generalized Walker constellations but cannot accommodate non-uniformity or streets-of-coverage. By inverting the integer lattice, one can define three continuous variables that generalize Flower and streets-of-coverage constellations while permitting non-uniform designs. Transitioning from integer parameters to continuous ones increases computational complexity but provides greater design flexibility and optimization. Both global navigation and regional coverage examples are provided, demonstrating the power of this new method.

15:10 Break 15:35 AAS 12 - 148 Perturbation Effects on Elliptical Relative Motion Based on Relative Orbit

Elements Jianfeng Yin and Chao Han, Beihang University

A new elliptical relative motion model with no singularity problem is derived based on the relative orbit elements. The inverse transformation of state transfer matrix is obtained to analyze perturbation effects and control strategy. The velocity impulse control laws, including out-of-plane and in-plane control, are also proposed. Mean orbit elements theory are introduced into the new dynamic model to analyze the perturbation effects, mainly J2. The effects of gravitational perturbations are simulated andanalyzed using the proposed feedback control method. The simulations presented clearly show that the new relative motion model could describe dynamics of formation flying more efficiently.

16:00 AAS 12 - 149 Review of the Solutions to the Tschauner-Hempel Equations for Satellite Relative Motion Andrew J. Sinclair and Ryan E. Sherrill, Auburn University; T. Alan Lovell, Air Force Research Laboratory

The Tschauner-Hempel equations model the motion of a deputy satellite relative to a chief satellite with arbitrary eccentricity. They are linear non-autonomous differential equations with the chief’s true anomaly as the independent variable. Since they first appeared, numerous analytical solutions have been presented. This paper provides a focused review of some of these solutions: highlighting how they are related and their singularities. The fundamental solutions of the Tschauner-Hempel equations can be interpreted geometrically as generalizations of the drifting two-by-one ellipse that describes relative motion in circular orbits. General solutions are formed by taking linear combinations of these fundamental solutions.

16:25 AAS 12 - 151 Three-Dimensional Linear Stability Analysis of Spinning Three-Craft Coulomb Formations Erik A. Hogan, Peter D. Jasch and Hanspeter Schaub, The University of Colorado at Boulder

This paper analyzes the stability of collinear three-craft Coulomb formations with set charges, assumed to be spinning in deep space. Previous work analytically proves in-plane marginal stability. However, the unstable out-of-plane motion is shown to decouple to first order from the marginally stable in-plane motion. Further, the degree of instability is small such that the departure drifts are reasonably slow. In this paper, the out-of-plane motion is analyzed in more detail. This paper illustrates that the unstable out-of-plane motion can be feedback stabilized without requiring in-plane motion control, yielding an elegant and simple spinning spacecraft cluster control strategy.


16:50 AAS 12 - 152 Velocity Extrema in Spacecraft Formation Flight Shawn E. Allgeier, University of Florida; R. Scott Erwin, Air Force Research Laboratory; Norman G. Fitz-Coy, University of Florida

This paper considers the analysis of relative motion between two spacecraft in orbit. Specifically, the paper seeks to provide bounds for relative spacecraft velocity- based measures which impact spacecraft formation-flight mission design and analysis. The range rate metric is derived and then bounded for certain special cases. A methodology for bounding the metrics is presented. The extremal equations for the range rate are formulated as an affine variety and solved using a Groebner basis reduction. A numerical example is included to demonstrate the efficacy of the method.


Jan 30, 2012 Colonial

Session 7: Optimal Control

Chair: Dr. Marcus Holzinger, Texas A&M University 13:30 AAS 12 - 153 Necessary Conditions for Optimal Impulsive Rendezvous in a

Newtonian Gravitational Field Thomas Carter, Eastern Connecticut State University; Mayer Humi, Worcester Polytechnic Institute

The problem of planar optimal impulsive rendezvous with fixed end conditions in a Newtonian gravitational field is approached through a transformation of variables that was recently used by the authors to successfully investigate the problem of optimal impulsive rendezvous near circular orbit. New necessary conditions for solution of this more general problem are presented in terms of these transformed variables.

13:55 AAS 12 - 154 Existence and Sufficiency Conditions for Optimal Impulsive Rendezvous in a Newtonian Gravitational Field Thomas Carter, Eastern Connecticut State University; Mayer Humi, Worcester Polytechnic Institute

An investigation of the question of existence of solutions of an optimal impulsive rendezvous in a Newtonian gravitational field reveals that if the initial and terminal angular momentum are positive, either a solution exists, or else an approximate solution exists to any degree of accuracy. If the differences in the values of the true anomaly where the velocity increments are applied are not integer multiples of pi, then an actual solution exists, not an approximate one. Under these conditions, necessary and sufficient conditions for optimality are available. An example is presented of an optimal solution having a finite radial distance.

14:20 AAS 12 - 155 Modified Chebyshev-Picard Iteration Methods for Station-Keeping of Translunar Halo Orbits Xiaoli Bai and John L. Junkins, Texas A&M University

The halo orbits around the Earth-Moon L2 libration point provide a great candidate orbit for a lunar communication satellite, where the satellite remains above the horizon on the far side of the Moon is visible from the Earth at all times. Such orbits are generally unstable and station-keeping strategies are required to control the satellite to remain close to the reference orbit. A recently developed Modified Chebyshev-Picard Iteration method is used to compute corrective maneuvers at discrete time intervals for station-keeping of halo orbit satellite and several key parameters affecting the mission performance are analyzed through numerical simulations.

14:45 AAS 12 - 157 Optimal Aeroassisted Orbital Transfer with Time Linear Control S. Praneeth Reddy and Ashish Tewari, Indian Institute of Technology

It is demonstrated that the solution of the nonlinear, two-point boundary value problem for optimal aeroassisted orbital transfer with minimal control effort and fixed terminal time leads to a time-linear control profile. Numerical results are compared with those of an approximate optimal, free terminal time scheme and observed to have a significant reduction in the maximum control input, control power, and maximum heating rate. The time linear control profle is shown to be typical, and can be easily implemented by a simple timing mechanism. An empirical relationship is derived for the control profile as a function of the entry conditions.


15:10 Break

15:35 AAS 12 - 158 Optimal Solutions and Guidance for Quasi-planar Ascent over a Spherical Moon David G. Hull and Matthew W. Harris, University of Texas at Austin

The minimum-time trajectory of a constant-thrust rocket in quasi-planar ascent from the surface of the moon to lunar orbit over a spherical moon is obtained for small thrust angles. The solution of the resulting TPBVP involves modified thrust integrals and requires an iteration. An indicated approximate solution exists leading to a non-iterative analytical solution in terms of the well known thrust integrals. Both solutions are tested in sample and hold guidance and satisfy the final conditions, consume the same mass, and use approximately the same thrust pitch angle history. The approximate solution merits further consideration for onboard guidance.

16:00 AAS 12 - 159 Space Object Maneuver Detection via a Joint Optimal Control and Multiple Hypothesis Tracking Approach Navraj Singh, Joshua T. Horwood and Aubrey B. Poore, Numerica Corporation

An optimal control framework is presented as a post-processor to a multiple hypothesis tracker (MHT) for resolving uncorrelated tracks (UCTs) generated by space object maneuvers. The optimal control framework uses the total velocity increment (delta-V) as the cost functional to determine feasibility of maneuvers. The method obtains accurate delta-V estimates for connecting two UCTs via fuel-optimal maneuvers. In addition, a method is proposed for treating uncertainty in the UCT states, via the unscented transform, to determine the probability that a maneuver is feasible. The approach is most applicable to routine but unannounced fuel-optimal maneuvers conducted by space objects.



Session 8: Trajectory Optimization I

Chair: Dr. Anil Rao, University of Florida 08:00 AAS 12 - 162 Automated Inclusion of V-Infinity Leveraging Maneuvers in Gravity-Assist

Flyby Tour Design Demyan Lantukh and Ryan Russell, The University of Texas at Austin; Stefano Campagnola, Jet Propulsion Laboratory

Interplanetary and moon tour missions have benefited from the implementation of leveraging maneuvers that efficiently change spacecraft energy relative to a flyby body. These v-infinity leveraging maneuvers are reformulated into a boundary value problem more suitable for broad trajectory searches and for the ephemeris case by using the same boundary conditions as the Lambert problem. A root-solve on a complicated one-dimensional function space results from this reformulation. The method allows the inclusion of maneuvers in broad tour design searches with few additional search dimensions while also keeping the Lambert-based architecture. Examples are presented using representative interplanetary and intermoon tours.

08:25 AAS 12 - 163 Closed-Form Solutions for Open Orbits Around an Oblate Planet Vladimir Martinusi and Pini Gurfil, Technion - Israel Institute of Technology

The paper develops the closed-form solution for the motion around an oblate planet in the situation wherein the orbit is unbounded. It is proven that when the effect of the J2 zonal harmonic is taken into account, the orbit is different from its Keplerian counterpart, having a marked influence on the deflection angle, thereby changing the Keplerian flyby geometry. Numerical simulations quantify this difference, which is closely related to the minimum flyby altitude of the spacecraft. The analytic developments can be applied to the preliminary design of gravity-assisted maneuvers.

08:50 AAS 12 - 164 Design of Optimal Transfers Between North and South Pole-Sitter Orbits Jeannette Heiligers, Matteo Ceriotti, Colin R. McInnes, and James D. Biggs, Advanced Space Concepts Laboratory, University of Strathclyde

Recent studies have investigated Earth pole-sitter missions where a spacecraft follows the Earth's polar axis to have a continuous, hemispherical view of the polar regions for Earth observation and high latitude telecommunications. However, the tilt of the polar axis causes the North and South poles to be alternately situated in darkness for long periods during the year which constrains observations and decreases the mission scientific return. This paper therefore investigates optimum, hybrid sail/SEP propulsion transfers between North and South pole-sitter orbits before the start of the Arctic and Antarctic winters to enable observation of the polar regions only when lit.

09:15 AAS 12 - 165 Efficient Lunar Gravity Assists for Solar Electric Propulsion Missions Damon Landau, Tim P. McElrath, Dan Grebow, and Nathan J. Strange, Jet Propulsion Laboratory

The combination of lunar gravity assists for Earth escape and around 1.25 year of V-infinity leveraging with SEP effectively boosts the performance of a given launch vehicle. Two methods are presented to establish a launch period with lunar gravity assists, where the energy achievable with lunar escape has been characterized as a function of right ascension, declination, and launch energy. The increased launch efficiency makes a Falcon 9 perform like an Atlas V (401) at low C3 or like an Atlas V (531) at high C3. An Atlas V (551) outperforms a Delta IV Heavy for C3 above 24 km2/s2.


09:40 Break 10:05 AAS 12 - 166 Global Optimization Techniques for Deep Space Trajectory Maneuvers Using

Satellite Tool Kit Sruthi Krishnan, Virginia Polytechnic Institute and State University

The European Space Agency (ESA) recently proposed a test problem to model the Cassini2 trajectory for global optimization. At present, algorithms for all proposed models are coded in Matlab or C++. This project introduces a new method by using algorithms that are built within the Satellite Tool Kit (STK) with the integration of Matlab to optimize the model trajectories necessary for deep space maneuvers. The Matlab code provided online by ESA is used to integrate with STK to optimize the current trajectory model for Cassini2. This project expects to find Delta-V results similar to current optimum value 8.383 km/sec.

10:30 AAS 12 - 167 Optimization of Debris Removal Path for TAMU Sweeper Jonathan Missel, and Daniele Mortari, Texas A&M University

This paper develops a method to evaluate and optimize the trajectory of a satellite designed for debris removal, focusing on the proposed TAMU Sweeper mission. Using an evolutionary algorithm, it observes interaction order, transfer trajectories, and sequence timing while optimizing fuel burned and effectiveness towards debris mitigation. For a fixed time interval and number of debris interactions, the most efficient and effective sequence is determined. Also, the debris mass estimation technique proposed with TAMU Sweeper is analyzed for sensitivity to elements of hardware design. The broader goal of this work is to evaluate feasibility of such missions.



Session 9: Attitude Dynamics and Control I

Chair: Dr. Yanping Guo, Johns Hopkins University Applied Physics Laboratory 08:00 AAS 12 - 168 Delayed Feedback Attitude Control Using Neural Networks and Lyapunov-

Krasovskii Functionals Ehsan Samiei, Morad Nazari and Eric A. Butcher, New Mexico State University; Hanspeter Schaub, University of Colorado at Boulder

This paper addresses the regulation control and stabilization problem of spacecraft attitude dynamics when there exists an unknown constant discrete delay in the measurements. Radial basis function neural networks are used to approximate the kinematic and inertial nonlinearities, while a back propagation algorithm is employed to update neural network weights. By employing a Lyapunov-Krasovskii functional, a delay independent stability condition is obtained in terms of a linear matrix inequality, the solution of which gives the suitable controller gains. Finally, simulations are performed and compared with results obtained using the method for delayed feedback control suggested by Ailon et al.

08:25 AAS 12 - 169 A New Method for Simulating the Attitude Dynamics of Passively Magnetically Stabilized Spacecraft Roland Burton and Joseph Starek, Stanford University and NASA Ames Research Center; Stephen Rock, Stanford University

A new method for simulating the attitude dynamics of passively magnetically stabilized spacecraft is presented that offers an order of magnitude reduction in simulation run time compared to existing methods with no loss in accuracy. The new method is applied to the modeling of the attitude dynamics of the ARC 3U nanosatellite bus, with simulation results compared to on orbit data from O/OREOS, a nanosatellite that was launched in late 2010. To improve simulation fidelity, magnetic properties of the type of hysteresis material used were measured in the laboratory at Ames Research Center.

08:50 AAS 12 - 170 Design of Satellite Control Algorithm Using the State-Dependent Ricatti Equation and Kalman Filter Luiz DeSouza, National Institute for Space Research - S.J. Campos; Victor Arena, Federal University of ABC - Santo André

This paper discusses application of the State-Dependent Riccati Equation (SDRE) method along with Kalman filter to design and test a control algorithm for a 3D attitude satellite simulator. The control strategy is based on gas jets and reaction wheel torques to perform large angle manuevers in three axes. The simulator model allows investigating the dynamics and the control system taking into account effects of the plant non-linearities and noises using the Kalman filter to estimate the unavailable states. Simulation has shown the performance and robustness of the SDRE controller applied for angular velocity reduction associated with a stringent "pointing requirement."


09:15 AAS 12 - 171 Artificial Potential Steering for Angular Momentum Exchange Devices Josue D. Munoz and Frederick A. Leve, Air Force Research Laboratory

The artificial potential function methodology is well-suited for avoiding saturation and steering away or through internal singularities in angular momentum exchange devices (AMED). The angular momentum artificial potential steering (AMAPS) method is developed by first defining a reference trajectory in the angular momentum space of the AMED. Next, the saturation for both reaction wheel assemblies (RWA) and control moment gyros (CMG) are handled by using a repulsive artificial potential function. The internal singularities of CMGs are handled by defining a potential to ensure that the columns of the Jacobian stay orthogonal.

09:40 Break 10:05 AAS 12 - 172 Converting Repetitive Control Robustification Methods to Apply to Iterative

Learning Control Yunde Shi and Richard Longman, Columbia University

Iterative learning control (ILC) can be used for high accuracy tracking with fine pointing equipment on board spacecraft that need to perform repeated scanning maneuvers. This paper converts methods of robustification of repetitive control systems used for vibration isolation on spacecraft to apply to the ILC problem. Robustification is particularly important for ILC since it asks for zero error in hardware tracking by iterating with the real world instead of a mathematical model. Model uncertainty is used directly in the ILC design process, to perform the minimum possible compromise in performance.

10:30 AAS 12 - 173 De-orbit Attitude Dynamics and Control of Spacecraft with Residual Fuel Based on Fluidic Ring Actuator Hong Guan and Shijie Xu, Beihang University

The fluidic ring actuator (FRA), based on the principle of conservation of angular momentum, is introduced in this paper. The FRA accelerates the fuel in the ring pipe to generate the control momentum, which is applied to stabilize the attitude of the spacecraft. The attitude control system of FRA is proposed. The simulation model of the attitude dynamics combined with the fluid dynamics is conducted. Simulation results show that the FRA is successful in stabilizing the attitude of the spacecraft in the presence of the disturbances of the fuel sloshing.

10:55 AAS 12 - 174 A Computational Efficient Suboptimal Algorithm for Dynamic Thruster Management Mengping Zhu, Min Liu and Shijie Xu, Beihang University

A computational efficient algorithm based on the searching of the optimal feasible cone is proposed to reduce the online computation load. The algorithm first concentrates on finding an optimal feasible cone for the unconstrained problem. Then, constraints are taken into account to select out the target thruster and compute the corresponding control contribution. Control error is thus obtained for next cycle until being eliminated. An Illustrative example based on the core module of space station is provided to verify the effectiveness of the proposed method as well as to demonstrate its advantage in computational requirement and adaptiveness to thruster failure.


11:20 AAS 12 - 175 Analysis of Small-Time Local Controllability of Spacecraft Attitude Using Two Control Moment Gyros Haichao Gui, Hong Guan, Shijie Xu and Lei Jin, Beihang University

Small-time local controllability of the dynamics of a spacecraft carrying two ar-bitrarily installed control moment gyros (CMGs) is investigated via nonlinear controllability theory. With the gimbal rates being treated as control inputs, STLC property of the system is found to be closely related to geometric posi-tions of two angular momentum vectors of the CMGs at the system equilibrium. The dynamics fails to be STLC when gimbals of the CMGs reach certain con-figurations resulting in saturation of their total angular momentum. Apart from these cases, the dynamics is STLC.



Session 10: Flight Dynamics Operations

Chair: Laurie Mann, a.i. solutions, Inc. 08:00 AAS 12 - 176 Effects of High Frequency Density Variations on Orbit Propagation

Craig A. McLaughlin, Dhaval M. Krishna and Travis Locke, University of Kansas

Accelerometer derived densities for CHAMP and GRACE have multiple high frequency variations that are not present in empirical density models or in density derived from precision orbit ephemeris (POE) data. These high frequency density variations appear in all data sets, but are especially prevalent during geomagnetic storms, near the polar cusps, and when the orbit plane is near the terminator. This paper examines the effects of these high frequency density variations on orbit propagation by comparing orbits propagated using accelerometer derived density to those propagated using POE derived density, High Accuracy Satellite Drag Model density, and Jacchia 1971 density.

08:25 AAS 12 - 177 End-of-Life Procedures for Air Force Missions: Orbital Debris Mitigation with CloudSat and TacSat-3 Michael Nayak, Space Development and Test Directorate, United States Air Force

At altitudes of less than 2,000 km, fragmentation wreckage caused by accidental explosions aboard spacecraft accounts for 42% of catalogued space debris. Using currently operational satellites CloudSat and TacSat-3 as examples, this paper discusses Air Force Space Command, NASA and DoD requirements for mitigation of orbital debris during creation of an End-of-Life (EOL) plan, detailing an outline for such plans with special applicability to military missions. EOL spacecraft passivation, re-entry survivability analysis, casualty expectation analysis, methods to assess debris generation due to intentional breakup, passivation, accidental explosions and on-orbit collisions; as well as USAF operational execution of EOL are covered.

08:50 AAS 12 - 178 Extended Mission Maneuver Operations for the Interstellar Boundary Explorer (IBEX) Ryan Lebois, Lisa Policastri, John Carrico Jr. and Marissa Intelisano, Applied Defense Solutions

This paper describes the operational strategies designed and executed by the IBEX Flight Dynamics Group to transfer IBEX from its nominal science orbit onto a Lunar-Resonant trajectory that is predictable beyond the expected lifetime of the spacecraft. This paper will highlight operational constraints involved in planning the Orbit Maintenance Maneuvers (OMMs) as well as the steps involved in calibrating the maneuvers, re-planning the maneuvers during operations, and analyzing the success of the OMM execution based on operational results. A comparison of current orbit predictions with the final pre-maneuver plan will also be discussed.

09:15 AAS 12 - 179 Flight Results of the Precise Autonomous Orbit Keeping Experiment on the Prisma Mission Sergio De Florio and Gianmarco Radice, University of Glasgow; Simone D’Amico, DLR

The Autonomous Orbit Keeping (AOK) experiment on the PRISMA mission was executed successfully from 18th of July to 16th of August 2011 demonstrating the capability of autonomous precise absolute orbit control. The main performance requirement was a control accuracy of the osculating ascending node of 10 m (1 sigma) with a maneuver budget of 0.5 m/s. The control accuracy requirement was fully fulfilled. The mean value of the LAN deviation controlled by AOK was -3.6 m with a standard deviation of 9.5 m during the fine control phase. The total delta-v spent during the entire experiment was 0.1347 m/s.


09:40 Break 10:05 AAS 12 - 180 Numerical Prediction of Satellite Surface Forces with Application to Rosetta

Benny Rievers, Takahiro Kato, Jozef van der Ha and Claus Lämmerzahl, University of Bremen

The precise determination of non-gravitational disturbances acting on a spacecrafts orbit is of major importance for accurate orbit determination, orbit propagation as well as the successful interpretation of scientific data. Most non-gravitational disturbances such as Solar radiation pressure (SRP) and thermal recoil pressure (TRP) interact with the spacecraft surface and thus strongly depend on the accurate modelling and implementation of the spacecraft's configuration. We present a numerical approach for the high precision determination of non-gravitational surface forces based on Finite Element modelling as well as a ray-tracing method. The method is applied in full detail to the Rosetta spacecraft.

10:30 AAS 12 - 181 Mass Ejection Anomaly in Lissajous Orbit: Response and Implications for the ARTEMIS Mission Brandon D. Owens, Daniel Cosgrove, Jeffrey E. Marchese, John W. Bonnell, David H. Pankow, Sabine Frey and Manfred G. Bester, University of California at Berkeley

On October 14, 2010, a 0.092 kg instrument sphere unexpectedly detached from the first spacecraft to ever orbit an Earth-Moon libration point and a quick response was required to prevent the spacecraft from falling out of Lissajous orbit. In this paper, the actions of the spacecraft operations team and the changes to the spacecraft’s flight characteristics are described for the benefit of future Earth-Moon libration point orbiting missions. Specifically, the authors detail how the timing of the event and response affected the trajectory of the departing sphere and the prospects of preventing the spacecraft’s fall out of Lissajous orbit.

10:55 AAS 12 - 182 Optimizing ARTEMIS Libration Point Orbit Stationkeeping Costs through Maneuver Performance Calibration Brandon D. Owens, Jeffrey E. Marchese, Daniel Cosgrove, Sabine Frey and Manfred G. Bester, University of California at Berkeley

The first two spacecraft to orbit earth-moon libration points’ARTEMIS P1 and P2’performed a total of 70 stationkeeping maneuvers over a period of 10 months. The degree of precision required for these orbit corrections exceeded that which had been obtained on these spacecraft prior to their Lissajous orbit insertions. This paper includes details of the in-flight calibration techniques used to obtain the necessary level of performance for these maneuvers. With these techniques, the operations team routinely reduced maneuver magnitude and phase errors to less than 2 millimeters/second and one degree, respectively (the minimum maneuver magnitude error was 46.3 micrometers/second).

11:20 AAS 12 - 183 Optimizing Solar Radiation Coefficient as a Solve-For Parameter for the Orbit Determination Process during the ARTEMIS Libration-Point Orbit Phase Jeffrey E. Marchese, Daniel Cosgrove, Brandon D. Owens, Sabine Frey and Manfred Bester, University of California at Berkeley; Mark Woodard and Dave Folta, NASA Goddard Space FLight Center; Patrick Morinelli, Honeywell Technology Solutions Inc.

The first two spacecraft to orbit Earth-Moon libration points--ARTEMIS P1 and P2--performed a total of 70 station-keeping maneuvers over a period of 10 months. With short durations between maneuvers and software restrictions that required data arcs be reset subsequent to each maneuver, it was critical to ensure that successive orbit determinations converged to an accurate solution in a timely manner. This paper details the in-flight techniques used to optimize solve-for parameters, such as solar radiation coefficient and a constraint on its standard deviation, in the orbit solutions to ensure accuracy and while still providing short convergence intervals.



Session 11: Dynamical Systems Theory II

Chair: Dr. David Spencer, Pennsylvania State University 13:30 AAS 12 - 184 Optimized Three-Body Gravity Assists and Manifold Transfers in End-to-End

Lunar Mission Design Piyush Grover, Mitsubishi Electric Research Labs; Christian Andersson, Lund University

We describe a modular optimization framework for GTO-to-moon mission design using the planar circular restricted three-body problem (PCR3BP) model. The three-body resonant gravity assists and invariant manifolds in the PCR3BP are used as basic building blocks of this mission design. The mission is optimized by appropriately timed delta-Vs, which are obtained by a shooting method and a Gauss-pseudospectral collocation method for different phases of the mission. Depending upon the initial and final orbits, the optimized missions consume between 10-15 % less fuel compared to a Hohmann transfer, while the time of flight is around 4 to 5 months.

13:55 AAS 12 - 185 Tisserand-Leveraging Transfer and Their Application to Real Missions Stefano Campagnola and Anastassios Petropoulos, Jet Propulsion Laboratory; Arnaud Boutonnet and Johannes Schoenmaekers, European Space Operations Center, ESA; Ryan P. Russell, The University of Texas at Austin

This paper introduces a new technique called Tisserand-leveraging transfers (TILTs) that reduces the orbit insertion maneuvers. TILTs connect two distant flybys at the minor body with an impulsive maneuver at an apse. Using the CR3BP, TILTs extend the concept of v-infinity leveraging beyond the patched-conics domain. In this paper we present a method to design TILTs and we apply them to proposed missions to the Jupiter moons Ganymede and Europa. We also show that the "lunar resonance" technique implemented by SMART1 can be re-interpreted as a sequence of low-thrust TILTs.

14:20 AAS 12 - 186 Utilization of Sun-Earth Libration Points as Staging Locations for Human Exploration Missions to Near-Earth Asteroids Aline K. Zimmer and Ernst Messerschmid, Institute of Space Systems, University of Stuttgart

In an effort to reduce the mass launched per mission, cargo modules are stationed in SEL orbits for reuse in subsequent missions in an effort to reduce the mass launched per mission. Performing Oberth maneuvers in close proximity to the Earth, the cargo modules rendezvous with the crew vehicle launched from Earth on the outbound trajectory to the NEA and return to the SEL orbit after the mission while the crew vehicle directly re-enters the Earth's atmosphere. The SEL orbits are matched to the interplanetary trajectory leg by means of a differential correction algorithm and the delta-v required is minimized.

14:45 AAS 12 - 187 Preliminary Study of the Transfer Trajectory from the Moon to the Halo Orbit for the Small Scientific Spacecraft, DESTINY Masaki Nakamiya and Yasahiro Kawakatsu, Japan Aerospace Exploration Agency

This study investigates the trajectory design of the small scientific spacecraft, DESTINY (Demonstration and Space Technology for INterplanetary voYage), which aims to be launched by the third Japanese next-generation solid propellant Epsilon rocket around 2016. In the DESTINY mission, the spacecraft will go to the moon by the ion engine from the large elliptical orbit. Afterward, the spacecraft will use a lunar swingby to go to the periodic orbit near the libration point (Halo orbit) of the Sun- Earth L2. This study focuses on the transfer trajectories from the moon to the Halo orbit.


15:10 Break 15:35 AAS 12 - 188 Circular Restricted Three-Body Problem with Photonic Laser Propulsion

F.Y. Hsiao, P.S. Wu, Z.W. Cheng, Z.Y. Yang, J.W. Sun, H.K. Chen, H.Y. Chen, Y.T. Jan, and D.H. Lien, Tamkang University

This paper studies the trajectory of spacecraft propelled by the photonic laser propulsion (PLP) system under the environment of circular restricted three-body problem (CRTBP). The PLP system is an innovative technology proposed by Dr. Bae. With repeated reflections of laser beam, it can generate continuous and tremendous power by consuming very small energy. This paper studies the trajectory under the CRTBP. At beginning, the PLP system At beginning, the PLP system is briefly introduced. Then we model the PLP system a force potential, and the conventional procedure of analysis to the CRTBP is applied. Numerical simulations are also provided.

16:00 AAS 12 - 189 Canonical Perturbation Theory for the Elliptic Restricted-Three-Body Problem Brenton Duffy and David F. Chichka, The George Washington University

Canonical transformations of a Hamiltonian system may be generated using Deprit’s Lie transform method such that the normalized system possesses ideal properties of integrability. The purpose of this study is to derive an extension of Deprit's method to non-autonomous, bi-parametric Hamiltonian systems and then to apply the extended method to the elliptic restricted three-body problem. The elliptic restricted three-body problem is represented in terms of a doubly-expanded Hamiltonian function and then normalized using the extended Deprit’s method. The resultant system is expressed in Birkhoff normal form such that the stability of the equilibrium points may be analyzed using KAM theory.

16:25 AAS 12 - 190 A Visual Analytics Approach to Preliminary Trajectory Design Wayne R. Schlei and Kathleen C. Howell, Purdue University

Visual analytics, a new science that combines visualization, human-computer interaction, and theoretical analysis, enhances the development of spacecraft trajectories in multi-body environments. The application of visual analytics supplies an immensely powerful tool for rapid research and development and access to a wider range of options for the construction of trajectories that meet mission requirements. This investigation connects spacecraft trajectory design with the implementation of visual analytics, thereby merging visualization tools, numerical algorithms, and designer knowledge into one expansive design approach.



Session 12: Spacecraft Guidance, Navigation, and Control I

Chair: Dr. Shyam Bhaskaran, Jet Propulsion Laboratory 13:30 AAS 12 - 191 Adaptive Pinpoint and Fuel Efficient Mars Landing Using Reinforcement

Learning Brian Gaudet and Roberto Furfaro, The University of Arizona

Future missions to Mars will require advanced guidance algorithms that are able to adapt to more demanding mission requirements, e.g. landing with pinpoint accuracy while autonomously flying fuel-efficient trajectories. In this paper we will present a novel guidance algorithm using reinforcement learning. Preliminary results show that one can achieve pinpoint landing accuracy with fuel consumption comparable to that of current practice. The algorithm has the potential to considerably expand the range of feasible landing sites. This appears, to the best of our knowledge, to be the first application of reinforcement learning to the problem of autonomous planetary landing.

13:55 AAS 12 - 192 Design and Assessment of Open-loop Variable Coast Time Guidance for the Mars Ascent Vehicle Kevin E. Witzberger, NASA Glenn Research Center; Dave Smith, Wyle LLC

A variable coast time open-loop guidance scheme for NASA’s Mars ascent vehicle (MAV) is described. An optimal two-stage trajectory is found using OTIS. The scheme utilizes a table lookup of optimal OTIS Euler angles for the powered portion of flight. A Newton-Raphson root-finding technique determines the upper stage ignition time that ensures the final altitude constraints are satisfied. Allowing the ignition time to be a free variable is a simple and straightforward way to accommodate environmental and hardware performance variations. The guidance scheme is implemented in MASTIF. Robustness of the guidance scheme is tested with Monte-Carlo dispersion simulations.

14:20 AAS 12 - 194 Flight-Path Control for Solar Sail Spacecraft

Geoffrey G. Wawrzyniak, a.i. solutions, Inc.; Kathleen C. Howell, Purdue University

Recent interest in missions to observe planetary poles or to communicate with an outpost at a lunar pole has motivated investigations of trajectory options that utilize solar sails. Designing reference trajectories and understanding their fundamental dynamics are necessary first steps toward flying spacecraft in dynamically complicated regimes. However, the existence of a reference orbit alone is insufficient for flight operations. Two variations of a turn-and-hold strategy are examined for flight-path control: an approach that implements multiple turns to achieve a target in an error-free scenario and an approach that incorporates a receding-horizon strategy to accommodate representative errors.

14:45 AAS 12 - 195 Integrated Guidance and Attitude Control for Pinpoint Lunar Guidance Using Higher Order Sliding Modes Daniel R. Wibben and Roberto Furfaro, University of Arizona

A novel non-linear guidance and attitude control scheme for pinpoint lunar landing is presented. Based on High Order Sliding Mode control theory, the proposed Multiple Sliding Surface Guidance and Control (MSSGC) algorithm has been designed to take advantage of the ability of the system to converge to the sliding surface in a finite time. The proposed approach is proven globally stable using a Lyapunov-based approach. Preliminary results demonstrate that the MSSGC law not only drives the spacecraft to the desired position with zero velocity, but also with the desired attitude and angular rates.


15:10 15:35

Break AAS 12 - 196

Waypoint-Optimized Zero-Effort-Miss/Zero-Effort-Velocity (ZEM/ZEV) Feedback Guidance for Mars Landing Yanning Guo, Matt Hawkins and Bong Wie, Iowa State University

This paper investigates the optimization approach to generate waypoint for the Mars landing problem employing Zero-Effort-Miss/Zero-Effort-Velocity (ZEM/ZEV) feedback guidance. By dividing the overall time into two or more time domains and discretizing dynamic equations in each segment, the performance index and constraints are expressed as to-be-determined waypoints, converting the original energy-optimal control problem to a nonlinear programming problem to find optimal waypoints. This novel idea exploits parameter optimization techniques for feedback control implementation, and combines the advantages of open-loop and closed-loop methods to achieve near optimal performance with acceptable robustness, while meeting various practical restrictions and requirements.

16:00 AAS 12 - 197 Zero-Effort-Miss/Zero-Effort-Velocity (ZEM/ZEV) Feedback Guidance:

Theory and Applications Matt Hawkins, Yanning Guo and Bong Wie, Iowa State University

This paper investigates the use of Zero-Effort Miss/Zero-Effort Velocity (ZEM/ZEV) feedback guidance for a variety of asteroid intercept and rendezvous missions. This guidance law is shown in most cases to be more effective than classical laws, such as proportional navigation. Through simulations, ZEM/ZEV guidance is compared with the open-loop optimal solution. It can approach optimal performance, with the robustness advantages of feedback. Practical limitations, such as collision avoidance and control saturation, are considered. A novel strategy for choosing one or more waypoints to further improve performance is given.



Session 13: Orbit Determination I

Chair: W. Todd Cerven, The Aerospace Corporation 13:30 AAS 12 - 198 Dual Accelerometer Usage Strategy for Onboard Space Navigation

Renato Zanetti, The Charles Stark Draper Laboratory; Chris D'Souza, NASA Johnson Space Center

This work introduces a dual accelerometer usage strategy for onboard space navigation. In the proposed algorithm the accelerometer is used to propagate the state when its value exceeds a threshold and it is used to estimate its errors otherwise. Numerical examples and comparison to other accelerometer usage schemes are presented to validate the proposed approach.

13:55 AAS 12 - 199 Expected Navigation Flight Performance for the Magnetospheric Multiscale (MMS) Mission Corwin Olson, Cinnamon Wright and Anne Long, a.i. solutions, Inc.; Russell Carpenter, NASA Goddard Space Flight Center

The Magnetospheric Multiscale (MMS) mission consists of four formation-flying spacecraft in highly elliptical orbits about the Earth. The primary mission objective is to study magnetic reconnection. The baseline navigation concept is the independent estimation of each spacecraft state using GPS pseudorange measurements referenced to an Ultra Stable Oscillator (USO) and accelerometer measurements during maneuvers. MMS state estimation is performed onboard each spacecraft using the Goddard Enhanced Onboard Navigation System, which is embedded in the Navigator GPS receiver. This paper describes the latest efforts to characterize expected navigation flight performance using upgraded simulation models derived from recent analysis.

14:20 AAS 12 - 200 Minimum L1 Norm Orbit Determination Using A Sequential Processing Algorithm Steven Gehly, Brandon Jones, Penina Axelrad and George Born, University of Colorado at Boulder

Orbit determination often involves processing noisy data containing outliers and biases, which result from physical instrumentation and modeling errors. Least squares filters assume a Gaussian distribution of the measurement errors, which may lead to poor performance for noisy data. The minimum L1 norm filter has the potential to aid current orbit determination filters in the space situational awareness (SSA) application. This paper develops a minimum L1 sequential processing algorithm and demonstratesits effectiveness in processing noisy data. Results of testing indicate this algorithm is a suitable first step toward removing the assumption of Gaussian error in the estimation process.

14:45 AAS 12 - 201 Orbit Determination Based on Variations of Orbital Elements Reza R. Karimi and Daniele Mortari, Texas A&M University

A novel technique of angles-only initial orbit determination based on variations of orbital elements is presented. The fact that the estimated orbit, both shape and orientation, should remain constant at every instant of time is the foundation of the new technique. The orbital elements are estimated for every measurement and the residuals are minimized with respect to the unknown ranges. In this formulation, the spacecraft ranges (leading to position and velocity vectors) along with the orbital elements are estimated all together. This method is also capable of using multiple observations.


15:10 Break

15:35 AAS 12 - 202 Relative Navigation for Satellites in Close Proximity Using Angles-Only Observations Hemanshu Patel, Georgia Institute of Technology; T. Alan Lovell, Air Force Research Laboratory; Andrew Sinclair, Auburn University; Ryan Russell, The University of Texas at Austin

This research investigates relative navigation using angles-only observations. Observability issues dictate that the unique relative orbit of a deputy satellite cannot be found using angles-only measurements from the chief satellite when a linear relative motion model is used. This work examines the possibility of partial observability in this case, which consists of a basis vector that corresponds to a family of relative orbits. A Preliminary Orbit Determination method is introduced that calculates an initial guess for the basis vector from three Line-of-Sight measurements. The application of both batch and extended Kalman filters to this problem is explored.

16:00 AAS 12 - 203 Preliminary Assessment of Orbit Restitution Capability of a Multiple-Antenna, GNSS Receiver on a Highly Elliptic Orbit Reaching above GNSS Altitude Stefano Casotto and Massimo Bardella, Universita' di Padova; Alberto Zin, Thales Alenia Space

Astronomical missions are often characterized by high altitude, highly elliptic orbits. We report on the results of a study on the orbit determination capability of a receiver equipped with several GNSS antennas on a 1,000 km by 25,000 km altitude orbit. Detailed visibility analysis shows how these antennas can help extend the tracking periods to GNSS constellations. Account is taken of the side lobe radio link allowed by the real GPS antennas radiation pattern. High accuracy OD is shown to be possible due to the smooth character of the force field, even in the presence of unmodelled attitude variations.

16:25 AAS 12 - 204 Second-Order Kalman Filter Using Multi-Complex Step Derivatives Vivek Vittaldev and Nitin Arora, Georgia Institute of Technology; Ryan P. Russell, The University of Texas at Austin; David Gaylor, Emergent Space Technologies, Inc.

The Second Order Kalman Filter (SOKF) uses second order Taylor series expansion (TSE) to account for non-linearities in an estimation problem. In this work, the derivatives required for the SOKF are computed using Multi-complex (MCX) derivatives. This method uses function overloading in order to compute the derivatives to machine precision without having to compute the derivatives analytically. Thus, the SOKF can be easily implemented, while at the same time having fewer tuning parameters than the second order sigma-point filters. The standard SOKF is also extended by using a square-root version and combining with Gaussian Mixture models (GMM).


Feb 1, 2012 Carolina A

Session 14: Lunar and Planetary Missions

Chair: Lauri Newman, NASA Goddard Space Flight Center 08:00 AAS 12 - 205 An Orbit Plan toward AKATSUKI Venus Re-encounter and Orbit Injection

Yasuhiro Kawakatsu, Chikako Hirose and Nobusaki Ishii, Japan Aerospace Exploration Agency; Stefano Campagnola, Jet Propulsion Laboratory

On December 7, 2010, AKATSUKI, the Japanese Venus explorer reached its destination and tried to inject itself into the Venus orbit. However, due to a malfunction of the propulsion system, the maneuver was interrupted and AKATSUKI again escaped out from the Venus into an interplanetary orbit. The telemetry data from AKATSUKI suggests the possibility to perform orbit maneuvers to reencounter the Venus and retry the Venus orbit injection. Reported in this paper is an orbit plan investigated under this situation. The latest results reflecting the test maneuver conducted in September, 2011 is introduced as well.

08:25 AAS 12 - 206 Practical Design of 3D Phasing Orbit in Lunar Transfer Trajectory Yasuhiro Kawakatsu, Japan Aerospace Exploration Agency

The moon is attracting attention again as a target of space exploration. To focus on the lunar transfer, there is a sequence named ‘phasing orbit’ which is different from the widely used direct transfer sequence. The design of the phasing orbit is simple under two body approximation, while the design under practical condition faces with the problems, namely ‘orbit connecting problem’ and ‘phase shifting problem’. In the paper, the methods to cope with these problems are clarified in detail with concrete example.

08:50 AAS 12 - 207 Mission Analysis for the JUICE Mission Arnaud Boutonnet and Johannes Schoenmaekers, HSO-GFA, ESA/European Space Operations Centre

This paper presents the mission analysis of JUICE, a mission to study Jupiter, its environment and its Galilean moons. This mission, inherited from EJSM Laplace, features new phases, like the Europa fly-bys or the Jupiter high inclined orbits. The Europa phase required a very specific strategy that minimises the radiation integrated dose. Jupiter high inclined orbits are obtained via resonant swing-bys with Callisto. There are also updates of Laplace like the moon resonant transfer to Ganymede, but also the Ganymede in-orbit science phase that uses frozen orbits based on the effect of Ganymede’s gravity potential and Jupiter’s attraction.

09:15 AAS 12 - 208 Sensitivity Analysis of Non-Gravitational Perturbations on a Mercury Orbiter Takahiro Kato, Benny Rievers, Jozef van der Ha and Claus Laemmerzahl, ZARM

This paper presents the effects of the non-gravitational forces acting on a Mercury orbiter. The effects induced by the Albedo and the InfraRed radiations originating from Mercury’s surface are expected to have significant effects on the orbital motion of the orbiter. Therefore, we study the effects of the Albedo and the InfraRed radiations from the planet Mercury in addition to the Solar Radiation Pressure and the Thermal Recoil Pressure. In order to obtain the practical illustration of the results, we introduce several assumptions and the orbital elements of NASA’s MESSENGER mission.

09:40 Break


10:05 AAS 12 - 210 Preliminary Mission Design for a Far-Side Solar Observatory using Low-Thrust Propulsion Jon Herman and Ron Noomen, Delft University of Technology

This paper discusses the preliminary mission design for a solar observatory placed on the far side of the Sun by means of low-thrust propulsion to allow for prolonged far-side observation. The research also investigates the heliocentric inclination that can be achieved with current or near-term propulsion technology to evaluate the feasibility of high-latitude observations. The optimization of the low-thrust trajectory is achieved through a direct method in a two-body model, using a nonlinear programming method for optimization.

10:30 AAS 12 - 211 On-Orbit Sail Quality Evaluation Utilizing Attitude Dynamics of Spinner Solar Sailer IKAROS Yuichi Tsuda, Yuya Mimasu and Ryu Funase, Japan Aerospace Exploration Agency; Yoshinobu Okano, Tokyo Metropolitan University

This paper describes a method of evaluating sail quality utilizing in-flight attitude behavior of spinning solar sailer IKAROS. Since the successful deployment of the sail, IKAROS has received SRP which strongly affects both translational and rotational motion of the spacecraft. Authors derived the ‘Generalized Spinning Sail Model (GSSM)’ to reproduce the observed unique attitude behavior of IKAROS. Following the previous work, this paper attempts to relate the GSSM with sail quality such as flatness and reflectivity variation. This method is useful not only for on-orbit sail performance evaluation, but also for quality assurance of sails in design and production processes.

10:55 AAS 12 - 212 Transfer of Impact Ejecta Material from the Surface of Mars to Phobos and Deimos L. Chappaz, H. J. Melosh, M. Vaquero and K. C. Howell, Purdue University

If successful, the Russian Phobos-Grunt mission will return approximately 200 grams of surface material from Phobos to Earth in mid-August 2014. Although it is anticipated that this material is mainly from the body of Phobos, there is a possibility that the sample may also contain material ejected from the surface of Mars by large impacts. An analysis of this possibility is performed using the best current knowledge of the different aspects of impact cratering on the surface of Mars and of the productionof high-speed ejecta that might be able to reach Phobos or Deimos.


Feb 1, 2012 Carolina B

Session 15: Numerical and Analytical Trajectory Techniques

Chair: Angela Bowes, NASA Langley Research Center

08:00 AAS 12 - 213 A Closed Form Solution of the Two Body Problem in Non-Inertial Reference Frame Daniel Condurache, Technical University of Lasi

In this paper a closed form solution of the fundamental two-body problem in non-inertial reference frame is presented. In order to obtain this solution a sym-bolic tensorial method is used. This approach generates new prime integrals for the two-body problem and the solution can be used for any central type interaction. If gravitational interaction is considered an explicit closed form solution is given using the hypercomplex eccentric anomaly. This is a new method pro-posed by the author of the paper andallows the solution to be expressed in a coordinate free vectorial form.

08:25 AAS 12 - 214 A Survey of Symplectic and Collocation Integration Methods for Orbit Propagation Brandon A. Jones, University of Colorado at Boulder; Rodney L. Anderson, Jet Propulsion Laboratory

Demands on numerical integration algorithms for astrodynamics applications continue to increase. Common methods, like explicit Runge-Kutta, meet most orbit propagation needs, but more specialized scenarios require new techniques to meet both computational efficiency and accuracy needs. This paper provides an extensive survey on the application of symplectic and collocation methods to astrodynamics. Both of these methods benefit from relatively recent theoretical developments, which improve their applicability to satellite orbit propagation. This paper also details their implementation, with several tests demonstrating their advantages and disadvantages.

08:50 AAS 12 - 215 Appropriate Modeling of Solar Radiation Pressure Effects on Uncontrolled Orbiting Objects for Accurate Dynamical Predictions Jay W. McMahon and Daniel J. Scheeres, University of Colorado at Boulder

The study of this SRP effects are often made by using a constant force model with zero torques, however improvement in the predictions can be made by using a more detailed model. This paper contains a comprehensive discussion of the effects seen with highly detailed dynamical models versus simplified models such as the cannonball model. The goal is to understand under what circumstances a more simplified SRP model can sufficiently describe the effects on a given orbiting object. The determination of the correct fidelity depends on the body properties, the dynamical state, and the time horizon, which are studied here.

09:15 AAS 12 - 216 Assessment of a New Numerical Integration Technique in Astrodynamics Ben K. Bradley, Penina Axelrad, Gregory Beylkin and Brandon A. Jones, University of Colorado at Boulder

Faster numerical integration techniques are needed to cope with the large increase in the space catalog that is expected due to improvements in tracking capabilities. This paper presents a new and innovative numerical integration technique and compares its efficiency at propagating orbits to existing techniques commonly used in astrodynamics today. This implicit Runge-Kutta scheme is shown to require significantly fewer force function calls than other integrators through the use of generalized Gaussian nodes and both low and high fidelity force models.

09:40 Break


10:05 AAS 12 - 217 Analytical Stability Analysis of Displaced, Geostationary Orbits using Perturbation Theory Andrew Rogers, Ryan Stanley and Troy Henderson, Virginia Tech

Recent research on trajectory design using low-thrust propulsion has opened up new avenues in orbital mechanics. One application is the displaced, geostationary orbit. A displaced orbit will afford the stationary component of the GEO belt, but in a noncrowded environment, as well provide the spacecraft with higher latitudes of continuous coverage. The equations of motion for this orbit are highly nonlinear, but there is a determined stability below which a satellite will be able to maintain station when perturbed, and above which the orbit will degrade. Specific perturbations will be analyzed for linearized cases and then verified numerically.

10:30 AAS 12 - 218 Comparison of Delaunay Normalization and the Krylov-Bogoliubov-Mitropolsky Method Juan F. San-Juan, Luis M. Lopez, David Ortigosa and Martin Lara, University of La Rioja; Paul J. Cefola, University at Buffalo (SUNY)

A scalable second-order analytical orbit propagator program (AOPP) is being carried out. This AOPP combines modern and classical perturbation methods in function of orbit types or the requirements needed for a space mission, such as catalog maintenance operations, long period evolution, and so on. As a first step on the validation and verification of part of our AOPP, we only consider the perturbation produced by the zonal harmonic coefficients in the Earth’s gravity potential, so that it is possible to analyze the behavior of the mathematical expression involved in the corresponding analytical theory in depth and determine its limits.

10:55 AAS 12 - 219 Detailed Analysis of Solar and Thermal Accelerations Acting on Deep-Space

Satellites Takahiro Kato, Benny Rievers, Jozef van der Ha and Claus Laemmerzahl, University of Bremen

This paper presents novel generic analytical and numerical approaches for modeling the Solar Radiation Pressure and Thermal Recoil Pressure effects for high accuracy applications. Good fidelity is achieved by implementing the detailed spacecraft model andthe operational history of the high-gain antenna as well as the spacecraft articulations. Both analytical and numerical approaches are applied in full detail to ESA’s current deep-space mission Rosetta during its cruise phases. The results of the two approaches are compared and evaluated with respect to the actually observed non-gravitational accelerations in orbit. The detailed analysis of the Thermal effects will also be presented.

11:20 AAS 12 – 220 Extension of the DSST Semi-analytical Theory Architecture Paul J. Cefola, University at Buffalo (SUNY); Zachary J. Folcik, MIT/Lincoln Laboratory; Chris Sabol, Air Force Research Laboratory; Keric Hill and Daron Nishimoto, Pacific Defense Solutions, LLC

The semi-analytical theory replaces the Cowell equations with two formulas: differential equations for the mean equinoctial elements, and short periodic formulas. There is a theory for the partial derivatives. An interpolation strategy produces the outputs. The semi-analytical theory has been interfaced with least squares and recursive estimation processes. Recently, the software architecture was extended so (1) the mean element equations and mean partial derivatives can be integrated backwards in time and (2) the epoch in a mean orbit determination process can have an arbitrary location in an observation span. The current paper describes the continued testing of these new capabilities.


Feb 1, 2012 Calhoun

Session 16: Asteroid and Near-Earth Object Missions II

Chair: Dr. Roby Wilson, Jet Propulsion Laboratory

08:00 AAS 12 - 221 Imaging LIDAR Mapping of Asteroids for Autonomy of Scout Spacecraft Bogdan Udrea, Parv Patel and Brandon Marsella, Embry-Riddle Aeronautical University; Paul Anderson, University of Colorado at Boulder

Autonomous proximity operations of an asteroid scout spacecraft are analyzed for the following operations: specifying requirements for the guidance navigation and control subsystem of the spacecraft, identifying performance metrics for on-board autonomy, and developing navigation and mapping algorithms. The focus of the paper is on the asteroid mapping with the LIDAR and point cloud reconstruction of the asteroid surface. The long term goal is to integrate the sensor models and the algorithms into an onboard autonomy architecture controlled by a system such as Jet Propulsion Laboratory's Continuous Activity Scheduling Planning Execution and Re-planning (CASPER).

08:25 AAS 12 - 222 Sensitivity Analysis of the Touchdown Footprint at (101955) 1999 RQ36 Bogdan Udrea, Parv Patel and Brandon Marsella, Embry-Riddle Aeronautical University; Paul Anderson, University of Colorado at Boulder

The NASA Origins Spectral Interpretation Resource Identification Security Regolith Explorer (OSIRIS-REx) mission is scheduled to launch in 2016. It is set to rendezvous with, map, and collect a sample from asteroid (101955) 1999 RQ36 in 2019, and return the sample to Earth in 2023. This paper addresses the analysis of the shapes and sizes of touchdown footprints for a spacecraft similar to OSIRIS-REx and its spacecraft-to-asteroid relative velocity at touchdown. Furthermore, alternative approaches for modeling the gravity field by finite and variable sphere models are examined for simulations. Conclusions will be drawn regarding the suitability and efficiency of these models.

08:50 AAS 12 - 223 Refined Gravity Determination at Small Bodies through Landing Probes Julie Bellerose, Carnegie Mellon University - NASA Ames Research Center

Spacecraft orbit determination at very small asteroids involves large error due to their very low mass. This results in higher error on bulk density estimation, and can affect subsequent operation planning. We investigate an additional mean for local gravity measurement using landing probes. The landing dynamics can be retrieved from relative motion and through the spacecraft orbit determination. We show simulations, performance, and mission concepts to measure and refine the mass and local density of an NEA using probes released from a spacecraft.

09:15 AAS 12 - 224 Surface Gravity Fields for Asteroids and Comets Yu Takahashi and D. J. Scheeres, University of Colorado at Boulder

The ultimate goal of a small body sample return mission is the retrieval of actual specimens from an asteroid, and a spacecraft must operate in close proximity to the asteroid’s surface to this end. However, the conventional expression of the spherical harmonic gravity field breaks down within the Brillouin sphere. To overcome this problem, we will introduce the theory of the interior gravity field, discuss the conversion between the spherical harmonic gravity field and the interior gravity field, and present a method to numerically approximate the interior spherical harmonics from a shape model with a homogeneous density distribution.

09:40 Break


10:05 AAS 12 - 225 Preliminary Design of Hypervelocity Nuclear Interceptor Spacecraft for Disruption/Fragmentation of NEOs Alan Pitz, Brian Kaplinger and Bong Wie, Iowa State University

When the warning time of an Earth-impacting NEO is short, a nuclear explosive device (NED) may become necessary to disrupt/fragment the target NEO. Given this situation, an original design of a versatile hypervelocity nuclear interceptor spacecraft (HNIS) is needed to execute a nuclear disruption option to the NEO. This paper describes the development of innovative technology and system architectures to aid in the design and analysis of a two-body interceptor configuration, targeting sensors, thermal shielding, and mission sequencing. Simulations using ADRC’s hydrodynamic code are conducted to calculate the thermal and structural limitations of the HNIS.

10:30 AAS 12 - 226 Target Selection for a Planetary Defense Technology Demonstration Mission Tim Winkler, Sam Wagner and Bong Wie, Iowa State University

During the past two decades, various technologies for mitigating the impact threat of near-Earth objects (NEOs) have been proposed and studied. Mitigation methods include nuclear explosions, kinetic impactors, and slow-pull gravity tractors. However, as of now, there is no consensus on how to reliably deflect or disrupt a hazardous NEO in a timely manner, nor have any of the necessary key technologies been validated on a flight demonstration mission. This paper presents at least 5 potential asteroid candidates for a planetary defense technology demonstration mission currently being studied at the Asteroid Deflection Research Center (ADRC).

10:55 AAS 12 - 227 The SIROCO Asteroid Deflection Demonstrator Claudio Bombardelli, Technical University of Madrid; Andres Galvez and Ian Carnelli, European Space Agency

The paper describes a space mission concept that could demonstrate some of the key technologies to rendezvous with an asteroid and accurately measure its trajectory during and after a deflection maneuver. The mission concept, called SIROCO, makes use of the recently proposed ion beam shepherd (IBS) concept where a stream of accelerated plasma ions is directed against the surface of a NEO to transmit a deflection force. We show that by carefully selecting the target NEO a measurable deflection can be obtained in a few weeks of thrust with a small spacecraft and state of the art electric propulsion hardware.

11:20 AAS 12 - 228 Validation and Application of a Preliminary Target Selection Algorithm for the

Design of a NEA Hopping Mission Michael V. Nayak, Kirtland Air Force Base; Bogdan Udrea, Embry-Riddle Aeronautical University

This paper describes the setup and results of an algorithm employed for preliminary asteroid target selection for a manned multi-asteroid prospecting mission. The algorithm is used to determine the order of transfer between viable targets, keeping delta-V at a minimum, minimizing the computational burden of optimization and maximizing the number of targets visited within the mission timeline. Based on distance from the originating asteroid, inclination change and planetary perturbation effects, the algorithm is employed to support a ‘decision-tree’ approach to target selection, with results validated using Satellite Tool Kit V.9.1’s Design Explorer and used to plan a six-asteroid hopping mission.



Session 17: Trajectory Optimization II

Chair: Dr. Ryan Russell, The University of Texas at Austin 13:30 AAS 12 - 230 Integrated Launch Window Analysis and Precision Transfer Trajectory Design

for Mars Missions Zhong-Sheng Wang, Embry-Riddle Aeronautical University

The iteration may not converge when linear correction is applied in precision transfer trajectory design for interplanetary missions. It was shown that the ‘rope-climbing’ algorithm can be applied to solve this problem effectively. This paper proposes amore efficient ‘rope-climbing’ scheme that leads to faster convergence. Also discussed is the important practical issue of integrating launch window analysis and precision transfer trajectory design for Mars missions. It is shown that an iterative procedure can be used to resolve this issue effectively. This work and the author’s previous work constitute a complete theory of conventional transfer trajectory design for Mars missions.

13:55 AAS 12 - 231 Iterative Model Refinement for Orbital Trajectory Optimization Jennifer Hudson and Ilya Kolmanovsky, University of Michigan

An iterative trajectory optimization method is developed for optimal control of a low-thrust spacecraft. A high-fidelity model and a low-fidelity model are used to iteratively refine solutions. The high-fidelity model accurately represents the system but has high computational complexity, such that numerical optimization is prohibitively time-consuming. The low-fidelity model can be used for numerical optimization, but approximates the system dynamics with an unknown error. The iterative model refinement method systematically reduces the difference between the two models and converges on a solution with efficient execution time.

14:20 AAS 12 - 232 New Orbit Propagator for Motion Around an Oblate Planet Vladimir Martinusi and Pini Gurfil, Technion - Israel Institute of Technology

This paper offers an alternative to the classical orbit variational equations, by proposing a new method for the numerical integration of perturbed orbits. The actual nominal orbit is considered to be the so called "J2 central orbit", which is modeled by the same initial value problem as the J2 problem, but with the colatitude-dependent terms excluded. This initial value problem has a closed-form solution, expressed using elliptic integrals, and it forms the generating solution for the perturbed problem.

14:45 AAS 12 - 234 Optimal Solar Sail Trajectory Analysis for Interstellar Missions Xiangyuan Zeng and Junfeng Li, Tsinghua University; K. T. Alfriend, Texas A&M University

Interstellar probe trajectory optimization using solar sails is investigated for a single solar photonic assistance. A new objective function with a variable parameter is adopted to find the truly global-time optimal solution using an indirect method. A technique of scaling the adjoint variables is used to make the optimization much easier than before. The influence of the departure point from the Earth orbit is discussed without consideration of the geocentric escape phase. During simulation, there is an interesting discovery that the angular momentum reversal trajectory is a local-optimal solution, which is discussed and compared with the direct flyby.

15:10 Break


15:35 AAS 12 - 235 Optimal Use of Perturbations for Space Missions Francesco de Dilectis and Daniele Mortari, Texas A&M University

In this study we use orbital perturbations as an aid in orbit design. Compared to previous studies, here the combined effect of many different perturbations is taken into account, by using a propagator based on the SGP4 method. Each satellite position on an assigned orbit can be considered a point in a 6-D space, and each can be propagated either backward or forward in time to determine a trajectory in such hyperspace. A genetic algorithm is then used to optimize the impulse sequence for maneuvers, or thestarting point in the configuration space for perturbed designed orbits.

16:00 AAS 12 - 236 Recent Improvements to the Copernicus Trajectory Design and Optimization System Jacob Williams, ERC Inc.; David Lee, NASA Johnson Space Center; Cesar Ocampo, The University of Texas at Austin; Juan Senent, Odyssey Space Research

The Copernicus trajectory design and optimization system represents a comprehensive approach to on-orbit mission design, trajectory analysis and optimization. Copernicus allows the user to design spacecraft missions, from simple to complex, to nearly all possible solar system destinations. The system accommodates the use of many types of propulsion systems, any number of spacecraft, and any user-definable force field model. This paper describes recent development of the tool at NASA/JSC, including the implementation of new features to allow greater flexibility to design gravity assist trajectories, halo orbit transfers, and low-thrust missions. Examples highlighting the Copernicus approach to mission design are given.



Session 18: Attitude Dynamics and Control II

Chair: Dr. Don Mackison, University of Colorado 13:30 AAS 12 - 237 Attitude Stabilization Using Nonlinear Delayed Actuator Control with an

Inverse Dynamics Approach Morad Nazari, Ehsan Samiei and Eric A. Butcher, New Mexico State University; Hanspeter Schaub, University of Colorado at Boulder

The dynamics of a rigid body with nonlinear feedback control and actuator delay are considered. A control law incorporating both delayed and non-delayed states is sought for the controlled system to have the desired linear closed-loop dynamics using an inverse dynamics approach. The closed-loop stability is shown to reduce to a second order linear delay differential equation for which the Hsu-Bhatt-Vyshnegradskii stability chart can be used to choose the control gains that result in a stable closed-loop response. Both analytical and numerical approaches are used to obtain the stability characteristics, while the controlled simulations agree with the stability predictions.

13:55 AAS 12 - 238 Backstepping Simple Adaptive Attitude Control and Disturbance Rejection for Spacecraft with Unmodeled Dynamics Min Liu, Shijie Xu and Chao Han, Beihang University

Based on backstepping control algorithm, a nonlinear backstepping simple adaptive controller is derived for spacecraft with unknown dynamics and disturbance. The spacecraft system is divided into the dynamics subsystem and the kinematics subsystem. Firstly, the angular velocity is selected as the intermediate control vector and a constant feedback intermediate control law is designed to stabilize the kinematics subsystem. Then backing a step, using backstepping method, nonlinear simple adaptive control method and Lyapunov-LaSalle approach, the backstepping adaptive attitude controller is derived. Finally, a numerical example is studied to validate the efficiency of the controller.

14:20 AAS 12 - 239 Hybrid Method for Constrained Time-Optimal Spacecraft Reorientation Maneuvers Robert G. Melton, Pennsylvania State University

Time-optimal spacecraft slewing maneuvers with path constraints are difficult to compute even with direct methods. This paper examines the use of a hybrid, two-stage approach, in which a particle swarm optimizer provides a rough estimate of the solution,and that serves as the input to a pseudospectral optimizer. Performance is compared between a particle swarm optimizer and a differential evolution optimizer in the first stage.

14:45 AAS 12 - 240 Laboratory Experiments for Position and Attitude Estimation using the Cayley Attitude Technique Kurt A. Cavalieri, Brent Macomber and John E. Hurtado, Texas A&M University; Manoranjan Majji, The State University of New York at Buffalo

Single point attitude determination is the problem of estimating the instantaneous attitude of a rigid body from a collection of vector observations taken at a single moment in time. A new attitude estimation technique uses a generalized Cayley transform and finds algorithms to optimally solve the attitude estimation problem for a wide family of attitude parameters. The four dimensional Cayley attitude technique provides an elegant solution to the single point position and attitude estimation problem. Robustness of this technique in the presence of noise is tested through experiments at the Land, Air, and Space Robotics Laboratory.


15:10 Break

15:35 AAS 12 - 241 Projective Geometry of Attitude Parameterizations with Applications to Estimation Sergei Tanygin, Analytical Graphics, Inc.

Vectorial attitude parameterizations, defined as products of the unit axis of rotation and various functions of the rotation angle, can be viewed as projections from the unit quaternion hypersphere onto a hyperplane tangential to this hypersphere. It is shown how additive and multiplicative errors can be geometrically interpreted using projective geometry of vectorial parameterizations. It is also shown how these errors can be propagated using variational equations derived and analyzed in the general form. The effect of specific generating functions of the rotation angle on the attitude error propagation is examined.

16:00 AAS 12 - 242 Under-Actuated Moving Mass Attitude Control for a 3U Cubesat Mission Brad Atkins and Troy Henderson, Virginia Polytechnic Institute and State University

An internal, linear two moving mass actuator system is being developed for consideration for the attitude control mechanisms of a Virginia Tech 3U CubeSat mission set to launch within the next year. The rotational dynamics about the instantaneous center of mass are presented independent of external torques followed by a full MATLAB dynamics simulation of moving mass profiles for a system comparable to the actual 3U CubeSat setup. The dynamics simulation demonstrates roll, pitch, and with coupled mass inputs, yaw maneuvers. The full paper will present both a linear and nonlinear control approach for pointing maneuvers.

16:25 AAS 12 - 243 Using Kane's Method to Incorporate Attitude Dynamics in the Circular Restricted Three Body Problem A.J. Knutson and K.C. Howell, Purdue University

The dynamical framework in the circular restricted three body problem (CR3BP) has been explored extensively in recent years for application to trajectory design; however, considerably fewer studies incorporate the effects of spacecraft attitude in this regime. Recent work has explored the motion of a single asymmetric rigid body in the vicinity of the Sun-Earth L2 point, using linear planar Lyapunov orbit approximations. The goal of the current investigation is the examination of the effects of combining attitude dynamics and non-linear orbital dynamics in the CR3BP, specifically offering comparable results in the Earth-Moon system.

16:50 AAS 12 - 244 Using the Magnetospheric Multiscale (MMS) TableSat IB for the Analysis of Attitude Control and Flexible Boom Dynamics for MMS Mission Spacecraft Timothy John Roemer, Nicholas F. Aubut, William K. Holmes, Joshua Chabot, Abigail Jenkins, Michael Johnson and May-Win L. Thein, University of New Hampshire

The NASA Magnetosphereic Multiscale (MMS) Mission (to be launched in 2014) consists of four spin-stabilized spacecraft (s/c) flying in precise formation. To analyze the MMS s/c with wire booms up to 60m long, the UNH MMS TableSat IB, a limited 3-DOF rotation (full spin, limited nutation) table top prototype of the MMS s/c, is used. A preliminary controller is implemented on TableSat IB to observe the effects of spin rate and nutation control on the experimental s/c bus as well as the scaled booms. The experimental results of the s/c bus are expected to match those of its analytical simulation.


Feb 1, 2012 Calhoun

Session 19: Orbital Debris

Chair: Dr. Thomas Starchville, The Aerospace Corporation 13:30 AAS 12 - 245 An Orbital Conjunction Algorithm Based on Taylor Models

Roberto Armellin, Pierluigi Di Lizia, Alessandro Morselli and Michele Lavagna, Politecnico di Milano

The study of orbital conjunctions between space bodies is of fundamental importance in space situational awareness programs. The identification of potentially dangerous conjunctions, either between Near Earth Objects and our planet, or space debris and operative spacecraft, is most commonly done by looking at the distance between the objects in a given time window. A method based on Taylor models and Taylor differential algebra is presented for the computation of the time of closest approach and the minimum distance, including the effect that uncertainties on orbital parameters and other quantities (e.g., spacecraft ballistic coefficient) produce on the conjunction.

13:55 AAS 12 - 246 Relative Dynamics and Control of an Ion Beam Shepherd Satellite Claudio Bombardelli, Hodei Urrutxua, Mario Merino, Eduardo Ahedo and Jesus Pelaez, Technical University of Madrid

The ion beam shepherd (IBS) is a recently proposed concept for modifying the orbit and/or attitude of a generic orbiting body in a contactless manner, which makes it a candidate technology for active space debris removal. In this paper we deal with the problem of controlling the relative position of a shepherd satellite coorbiting at small separation distance with a target debris. After deriving the orbit relative motion equations including the ion beam perturbation we study the system stability and propose different control strategies.

14:20 AAS 12 - 247 Including Velocity Uncertainty in the Probability of Collision Between Space Objects Vincent T. Coppola, Analytical Graphics, Inc.

While there has been much research on computing the probability of collision between space objects, there is little work on incorporating velocity uncertainty into the computation. We derive the formula from first principles, including both position and velocity uncertainty. Moreover, trajectories will evolve according to differential equations and not by approximating the relative motion. The end result is a 3-dimensional integral over time on the surface of a sphere. We show that the formula recovers the standard formula in the limit as the uncertainty approaches zero. Several examples will show the impact of the velocity uncertainty on the probability.

14:45 AAS 12 - 248 Evaluating the Short Encounter Assumption of the Probability of Collision Formula Vincent T. Coppola, Analytical Graphics, Inc.

The formula for the probability of collision for space objects results from a myriad of assumptions about the motion of the objects, not least of which is that the encounter duration is short. We develop a formula that characterizes the encounter durationfor the conjunction of two space objects. We then compute the encounter duration for every conjunction in an all-on-all assessment of the entire public catalog. The encounter duration metric provides the means for assessing whether a conjunction satisfies the short encounter assumption so that the standard collision probability metric is valid.

15:10 Break


15:35 AAS 12 - 249 Lambert Targeting for On-Orbit Delivery of Debris Remediation Dust Liam M. Healy, Naval Research Laboratory

Rapid delivery of material on-orbit (without regard to final velocity) is possible by pre-positioning on orbit a vehicle with the intended cargo. If the goal is to reach a specified point in inertial space to precede the return of another vehicle to that point using Lambert targeting, and there is a limit to the amount of delta v available, then certain orbits are better choices than others. For dispensing a dust to enhance drag for elimination of debris, I examine the combination of vehicles which gives the most coverage to treat the most populous altitude band of satellites.

16:00 AAS 12 - 250 Spacecraft Debris Avoidance Using Positively Invariant Constraint Admissible Sets Morgan Baldwin and R. Scott Erwin, Air Force Research Laboratory; Avishai Weiss and Ilya Kolmanovsky, University of Michigan

To cope with the rapidly growing amount of space debris, the spacecraft debris avoidance maneuvering capabilities need to be developed. In this paper, we propose an approach to debris avoidance maneuvering based on the use of safe positively invariant sets to steer the spacecraft, under closed-loop control, around the debris. Simulation results are reported that illustrate this approach.

16:25 AAS 12 - 251 Target Identification and Delta-V Sizing for Active Debris Removal and Improved Tracking Campaigns Glenn E. Peterson, The Aerospace Corporation

Long-term projections of the low Earth orbit debris environment show the number of objects is increasing, even without future launches. Various proposals have been made to mitigate the growth including actively removing objects from orbit or tracking currently orbiting objects to a greater degree of precision to facilitate more effective risk assessment. However, the cost of single removal or tracking missions is most likely prohibitive. An alternative is for a single mission to engage multiple targets. This paper determines desirable targets for such missions in terms of likelihood of future debris production and minimization of delta-V requirements.

16:50 AAS 12 - 252 Tethered Tug For Large Low Earth Orbit Debris Removal Lee Jasper, Hanspeter Schaub and Carl Seubert, University of Colorado at Boulder; Valery Trushkyakov and Evgeny Yutkin, Omsk State Technical University

The low Earth orbit debris environment continues to be a concern for the space community. A debris removal system is proposed which uses fuel reserves from the second stage of a heavy launch vehicle after it has delivered its primary payload. Upon tethering (a Soyuz-like craft) to a large debris object, such as a Cosmos-3M rocket body, a burn is performed to lower both objects’ periapses. The tether dynamics are modeled similar to a spring-mass and then explored with emphasis on collision avoidance. On-orbit dynamics reduce collision likelihood however throttle adjustments can also avoid collisions.



Session 20: Earth Orbital Missions

Chair: Dr. Xiaoli Bai, Texas A&M University 08:00 AAS 12 - 253 APCHI Technique for Rapidly and Accurately Predicting Multi-restriction

Satellite Visibility Xiucong Sun, Hongzheng Cui and Chao Han, Beihang University

Multi-restriction Satellite Visibility Prediction (MSVP) problem is of great significance in space missions such as Earth observation and space surveillance. This paper presents a numerical method to rapidly and accurately compute site-satellite and satellite-satellite access time, taking various restrictions into consideration. APCHI (Adaptive Piecewise Cubic Hermite Interpolation) technique is introduced to accomplish curve fitting for approximating waveforms that represent restriction functions. Test results obtained from this approach are almost identical to those obtained with brute force method but cost less time. At last, this method is more broadly applicable compared with other methods advanced in this research area.

08:25 AAS 12 - 254 Landsat Data Continuity Mission (LDCM) Ascent and Operational Orbit Design Laurie Mann, Ann Nicholson and Susan Good, a.i. solutions, Inc.;Mark Woodard, NASA Goddard Space Flight Center

For the past 40-years, Landsat Satellites have collected Earth’s continental data and enabled scientists to assess change in the Earth’s landscape. The Landsat Data Continuity Mission (LDCM) is the next generation satellite supporting the Landsat science program. LDCM will fly a 16-day ground repeat cycle, Sun-synchronous, frozen orbit with a mean local time of the descending node ranging between 10:10 am and 10:15 am. LDCM is scheduled to launch in December 2012 on an Atlas 5 launch vehicle. This paper will present the preliminary ascent trajectory design from the injection orbit to its final operational orbit.

08:50 AAS 12 - 255 Launch Window Analysis for the Magnetospheric Multiscale Mission Trevor Williams, NASA Goddard Space Flight Center

The NASA Magnetospheric Multiscale mission will study the magnetosphere using four spacecraft in eccentric orbit, with launch in late 2014. The orbit must satisfy many constraints, both scientific and engineering, at points months after launch. Mapping these to the launch orbit is complicated: the low perigee gives significant oblateness effects; the high apogee gives significant lunisolar perturbations. This paper describes a new launch window tool that uses a VOP equation model of the dominant perturbations, plus geometric interpretations of the constraints, to produce (in 10 s on a laptop) a graphical representation of the launch window for a given date.

09:15 AAS 12 - 256 Two Geometric Aspects of the Orbiting Carbon Observatory Mission Mark A. Vincent, Raytheon Intelligence and Information Systems

Two completely separate analyses will be presented in this paper. They both have been performed in support of the re-flight of the Orbiting Carbon Observatory (OCO-2). The first involves the location that the mission has been allocated at the front of theA-Train. The geometry involved in safely staying in front of JAXA’s soon-to-be-launched GCOM-W1 while avoiding the tail of the Morning Constellation will be described. The other analysis involves the geometry in obtaining the OCO-2 measurements while in Glint Mode. The algorithms for calculating the Glint Spot on a smooth sphere and an ellipsoid will be described and compared.


09:40 Break

10:05 AAS 12 - 257 Static Highly Elliptical Orbits Using Hybrid Low-Thrust Propulsion Pamela Anderson and Malcolm Macdonald, University of Strathclyde

Newly proposed, static highly elliptical orbits using hybrid solar-sail/solar electric propulsion, for free selection of ‘critical inclination’ are investigated. These orbits, termed Taranis orbits, use continuous acceleration, to compensate for the drift in argument of perigee caused by Earth’s gravitational field. Two cases are considered, firstly where the spacecraft launch mass is fixed which is shown to produce negligible increase in mission lifetime. Secondly, the maximum thrust of the thruster is fixed, which is shown to increase the lifetime of the mission. Strawman mass budgets are conducted for each case, as well as sizing of solar arrays, propellant tanks and solar-sails.

10:30 AAS 12 - 258 Sun-Synchronous Orbit Slot Architecture: Analysis and Development Eric Watson, California Polytechnic State University; T. Alan Lovell, Air Force Research Laboratory

Growing concern over the space debris issue as well as a possible influx in space traffic will create a need for increased space traffic management. Currently, an orbital slot framework is internationally agreed upon for geostationary satellites. Sun-synchronous orbit is the next logical orbit regime to apply a slot architecture, due to its population density and likely future growth. This paper furthers work done in Sun-synchronous orbit slot architecture design by accomplishing in-depth analysis, presenting a slot architecture based on the results of that analysis, and proposing a strategy for future design.

10:55 AAS 12 - 259 Preliminary Design of a Mini-Satellite for Drag Estimation (MinDE) D. Armstrong, R. Despins, C. Doerper, A. DuVal, M. Gambal, A. Garcia, D. Haller, N. Murphy, G. Peters, J. Rubino, J. Slane, M. Wolfson, K. Fanelli and B. Udrea, Embry-Riddle Aeronautical University; F. Herrero , NASA Goddard Space Flight Center

The Mini-Satellite for Drag Estimation is a proposed design for a satellite capable of accurately determining atmospheric densities in low Earth orbit. Current density values have error deviations of 10-15% arising from uncertainties in the measurements taken. It is the goal of the proposed satellite to reduce this error to 1% or less. Reduction is possible through the careful design of the satellite's drag coefficient and by employing highly accurate accelerometers and miniature mass spectrometers. The paper presents the preliminary design of the satellite with detail of the mass, power, and link budgets.



Session 21: Orbit Determination II

Chair: Lisa Policastri, Applied Defense Solutions 08:00 AAS 12 - 260 Initial Orbit Determination via Gaussian Mixture Approximation of the

Admissible Region Kyle J. DeMars and Moriba K. Jah, Air Force Research Laboratory

The concept of the admissible region for optical angles and their rates provides a convenient method for bounding the set of all possible range/range-rate combinations that can provide Earth-bound orbit solutions. Previous approaches to the problem of utilizing the admissible region for initial orbit determination have implemented discretization schemes to generate either hypotheses or triangulations which are then forecast in order to assimilate future incoming data. This work investigates a method that applies Gaussian mixture approximations to the admissible region in order to generate an initial probability density function that is associated with uniform ambiguity within the admissible region.

08:25 AAS 12 - 261 Methods for Splitting Gaussian Distributions and Applications within the

AEGIS Filter Kyle J. DeMars and Moriba K. Jah, Air Force Research Laboratory; Yang Cheng, Mississippi State University; Robert H. Bishop, Marquette University

The tracking of space objects is characterized by the lack of frequent observations of the objects. As such, long periods of time in which the object’s uncertainty must be propagated are often encountered. The AEGIS filter has been proposed for uncertainty propagation. The AEGIS filter employs an online adaptation of a Gaussian mixtures representation of the space object’s uncertainty by applying splitting libraries.. This work examines several cost functions based on information theoretic divergences in order to develop alternate splitting libraries and and assesses the libraries in the context of uncertainty propagation for space object tracking.

08:50 AAS 12 - 262 Solution of the Liouville’s Equation for Keplerian Motion: Application to Uncertainty Calculations Manoranjan Majji, University at Buffalo; Kyle Alfriend and Ryan Weisman, Texas A&M University

In the absence of process noise, the evolution of uncertainty for nonlinear dynamical systems is governed by the stochastic Liouville’s equation. The first order, n-dimensional partial differential equation can be solved in closed form by the method of characteristics. However, much simpler techniques can be employed to solve this equation. This paper proposes the use of the transformation of variables formula to develop a closed form analytic solution to the probability density function at any time t, given the initial condition uncertainty in terms of a density function. Applications orbit uncertainty calculations are also discussed.

09:15 AAS 12 - 263 Non-Linear Propagation of Uncertainty with Non-Conservative Effects Kohei Fujimoto and Daniel J. Scheeres, The University of Colorado at Boulder

One topic of interest in space situational awareness (SSA) is the accurate and consistent representation of an observed object's uncertainty under non-linear dynamics, which can be approached analytically by employing a special solution to the Fokker-Planck differential equations for Hamiltonian dynamical systems. In this paper, we expand this method to include the effects of non-conservative forces. In order to describe the evolution of a pdf over time for a dynamical system with no diffusion, one only needs to find the solution flow to the dynamics regardless of whether the forces are conservative or not.


09:40 Break

10:05 AAS 12 - 264 Nonlinear Management of Uncertainties in Celestial Mechanics Monica Valli, Roberto Armellin, Pierluigi Di Lizia and MichŠle Lavagna, Politecnico di Milano

The problem of nonlinear uncertainty propagation represents a crucial issue in celestial mechanics. In this paper a method for nonlinear propagation of uncertainties based on differential algebra is presented. Working in the DA framework enables a general approach to nonlinear uncertainty propagation that can provide high estimate accuracy with low computational burden. The nonlinear mapping of the statistics is here shown adopting the two-body problem as working framework, including coordinate system transformations. The general feature of the proposed method is also demonstrated by presenting long-term integrations in a complex dynamical framework, such as the n-body problem.

10:30 AAS 12 - 265 Quadrature Methods for Orbit Uncertainty Propagation under Solar Radiation Pressure Matthew R. Turnowicz, Bin Jia, Ming Xin and Yang Cheng, Mississippi State University; Kyle J. DeMars and Moriba K. Jah, Air Force Research Laboratory

Long-term orbit uncertainty propagation for space objects needs to account for the effect of solar radiation pressure. With the flat-plate model for solar radiation pressure, the orbital motion is coupled with the attitude motion, resulting in high-dimensional integration in propagation of the moments of the orbital and attitude parameters. Three quadrature methods (the Monte Carlo method, the Quasi-Monte Carlo method, and the sparse grid method) are applied to the moment propagation problem and compared in simulation of geosynchronous orbits over one day, one week, and one month. The quadrature methods are easy to implement and can handle Gaussian and non-Gaussian distributions.


Feb 2, 2012 Calhoun

Session 22: Spacecraft Guidance, Navigation, and Control II

Chair: Dr. Felix Hoots, The Aerospace Corporation 08:00 AAS 12 - 267 Application of the Generalized Transfer Equation for Mission Planning

Darren D. Garber, University of Southern California

This paper describes the Generalized Transfer Equation which extends the technique of patched conics to now include any curve as a template to account for perturbed orbits and powered flight trajectories. Through the derived Generalized Transfer Equation the velocity necessary to transfer between any two orbits can be determined directly. The utility of this approach is demonstrated for maneuver and mission planning by enabling the use of both impulsive maneuvers and low-thrust profiles to model the trajectory.

08:25 AAS 12 - 268 Asymptotic Solution for the Two Body-Problem with Low-Thrust Manuel Sanjurjo-Rivo, Universidad Carlos III; Claudio Bombardelli and Jesus Pelaez, Universidad Politcnica de Madrid

An analytical solution of the restricted two-body problem with low thrust is derived. The methodology to obtain the solution is based on perturbation theory techniques. The thrust magnitude is represented by a small parameter, whereas the direction of the thrust is determined by two variable angles. The mass variation along the trajectory and its impact on the low-thrust acceleration are also accounted for. A comparison with high-accuracy numerical results is made in order to show the suitability of the analytical solution to reproduce interplanetary trajectories and Earth orbit transfers with small error.

08:50 AAS 12 - 269 Frozen Orbits for Scientific Missions Using Rotating Tethers

Hodei Urrutxua, Jesus Pelaez and Martin Lara, Technical University of Madrid

We give an insight into the potential applications of rotating space tethers for the exploration of planetary satellites, pursuing a semi-analytic model that permits to study the influence of a tether in the design of orbits of interest for science missions. This model eases the analysis of the long-term evolution of the tether's attitude, unveiling a precession of its rotation plane. In addition, the model is applied to the search for frozen orbits, revealing promising orbit stabilization features that allow for the modification of frozen orbits by purely mechanical means, which leads to lower eccentricity orbits.

09:15 AAS 12 - 270 Backstepping Adaptive Control for Flexible Space Structure with Noncollocated Sensors and Actuators Min Liu, Shijie Xu and Chao Han, Beihang University

A new nonlinear back-stepping adaptive control method is presented and applied to large flexible structures with non-collocated sensor and actuator pairs. Utilizing the backstepping method, decompose the structure system into a dynamic subsystem and a kinetic subsystem. The velocity output is selected as a virtual control vector. A constant coefficient feedback intermediate control laws is designed to stabilize the kinetic subsystem. Then the backstepping adaptive control law for flexible structures is derived by Lyapunov theory and the positive real theory. Finally, a general example of noncollocated flexible space structure is used to demonstrate the efficiency of the controller.

09:40 Break


10:05 AAS 12 - 272 Solving and Analyzing Relative Lambert's Problem through Differential Orbital Elements Changxuan Wen, Yushan Zhao, Baojun Li and Peng Shi, Beijing University of Aeronautics and Astronautics

With the application of differential orbital elements and Lagrange’s time equation, a novel approach is developed to solve relative Lambert's problem on circular reference orbit. Then the problem is analyzed to explain the causes and find out the conditions of singularity occurrence. Analytical results reveal that any significant change of classical orbit elements with respect to the reference orbit will lead to singularity. However, singularities can be avoided by adjusting the initial and final relative positions properly.

10:30 AAS 12 - 273 Three Lambert Formulations with Finite, Computable Bounds Marc DiPrinzio, The Aerospace Corporation

Three parameterizations of the classical Lambert problem are described. Relations are derived so the flight path angle, true anomaly, and argument of perigee can each be used as the independent variable to solve Lambert’s problem. It is shown that each of these parameters have finite, computable bounds; therefore, the desired root is ‘bracketed’ in this known interval. While many root-finding algorithms exist, some of these offer guaranteed convergence (at least theoretically) for a bracketed root. These methods are unlikely to replace the elegant transformational methods of Battin or Gooding, but remain of interest due to their novelty and simplicity.


AUTHOR INDEX Author Session Ahedo, E. 19 Alfano, S. 2 Alfriend, K. 2, 17, 21 Allgeier, S. 6 Anderson, P. 16, 20 Anderson, R. 5, 15 Andersson, C. 11 Arena, V. 9 Armellin, R. 19, 21 Armstrong, D. 20 Arora, N. 13 Atkins, B. 18 Aubut, N. 18 Axelrad, P. 13, 15 Bae, J. 1 Bai, X. 7 Baldwin, M. 19 Barbee, B. 4 Bardella, M. 13 Bellerose, J. 4, 16 Bernelli-Zazzera, F. 5 Bester, M. 10 Betti, R. 5 Beylkin, G. 15 Biggs, J. 8 Bishop, R. 21 Bombardelli, C. 4, 16, 19, 22 Bonnell, J. 10 Born, G. 13 Boutonnet, A. 11, 14 Bradley, B. 15 Burton, R. 9 Butcher, E. 9, 18 Campagnola, S. 8, 11, 14 Carnelli, I. 16 Carpenter, R. 13 Carrico Jr., J. 10 Carter, T. 7 Casotto, S. 13 Cavalieri, K. 18 Cefola, P. 6, 15 Ceriotti, M. 8 Cersosimo, D. 4 Chabot, J. 18 Chao, H. 6 Chappaz, L. 14 Chen, H. 11 Cheng, Y. 3, 21 Cheng, Z. 11 Chichka, D. 11 Condurache, D. 15 Coppola, V. 19 Cosgrove, D. 10

Author Session Crassidis, J. 2, 3 Cui, H. 6, 20 D'Amico, S. 10 Davis, J. 6 de Dilectis, F. 17 De Florio, S. 10 DeMars, K. 3, 21 DeSouza, L. 9 Despins, R. 20 Di Lizia, P. 19, 21 DiPrinzio, M. 22 Doerper, C. 20 Draim, J. 6 D'Souza, C. 13 Duffy, B. 11 DuVal, A. 20 Erwin, R. 2, 6, 19 Fanelli, K. 20 Ferrer, S. 3 Finkleman, D. 6 Fitz-Coy, N. 3, 6 Folcik, Z. 15 Folta, D. 10 Frey, S. 10 Fujimoto, K. 21 Funase, R. 14 Furfaro, R. 4, 12 Galvez, A. 16 Gambal, M. 20 Gangestad, J. 2 Garber, D. 22 Garcia, A. 20 Gaudet, B. 12 Gaylor, D. 13 Gehly, S. 13 Good, S. 20 Goyal, P. 2 Grebow, D. 8 Grover, P. 11 Guan, H. 9 Gui, H. 9 Guo, Y. 12 Gurfil, P. 8, 17 Guzzetti, D. 5 Haller, D. 20 Hamada, K. 2 Han, C. 1,6, 18, 20, 22 Harms, A. 2 Haro, A. 4 Harris, M. 7 Hawkins, M. 12 Healy, L. 1, 19 Heiligers, J. 8

Author Session Henderson, L. 2 Henderson, T. 15, 18 Henshaw, G. 1 Herman, J. 14 Hernandez, S. 4 Herrero, F. 20 Hill, K. 15 Hirose, C. 14 Hogan, E. 6 Holmes, W. 18 Holzinger, M. 2 Horwood, J. 7 Howell, K. 11, 12, 14, 18 Hsiao, F. 11 Hudson, J. 17 Hull, D. 7 Humi, M. 7 Hurtado, J. 3, 18 Intelisano, M. 10 Ishii, N. 14 Jah, M. 2, 21 Jan, Y. 11 Jasch, P. 6 Jasper, L. 19 Jenkins, A. 18 Jia, B. 21 Jin, L. 9 Johnson, M. 18 Johnson, S. 3 Jones, B. 13, 15 Jones, D. 1 Junkins, J. 7 Kaplinger, B. 16 Karimi, R. 13 Kato, T. 10, 14, 15 Kawakatsu, Y. 5, 11, 14 Kim, Y. 1 Knutson, A. 18 Kolmanovsky, I. 17 ,19 Krishna, D. 10 Krishnan, S. 8 Lacy, S. 3 Lämmerzahl, C. 10, 14, 15 Landau, D. 8 Lang, T. 2 Lantukh, D. 8 Lara, M. 3, 15, 22 Lavagna, M. 5, 19, 21 Lebois, R. 10 Lee, D. 17 Lee, S. 6 Leve, F. 9 Li, B. 5, 22


Author Session Li, J. 17 Lien, D. 11 Lim, T. 3 Linares, R. 2, 3 Liu, M. 9, 18, 22 Locke, T. 10 Long, A. 13 Longman, R. 5, 9 López, L. 15 Lovell, T. 1, 6, 13, 20 Luu, K. 2 Macdonald, M. 20 Macomber, B. 18 Majji, M. 18, 21 Mann, L. 1, 20 Marchese, J. 10 Marsella, B. 16 Martinusi, V. 8, 17 McElrath, T. 8 McInnes, C. 4, 8 McLaughlin, C. 10 McMahon, J. 15 Melosh, H. 14 Melton, R. 18 Merino, M. 19 Messerschmid, E. 11 Mimasu, Y. 14 Mingotti, G. 5 Misra, A. 4 Missel, J. 8 Mondelo, J. 4 Morinelli, P. 10 Morselli, A. 19 Mortari, D. 3, 6, 8, 13, 17 Murphy, N. 20 Munoz, J. 9 Nakamiya, M. 5, 11 Nayak, M. 9, 10, 16, 18 Nazari, M. 9, 18 Nicholson, A. 20 Nishimoto, D. 15 Noomen, R. 14 Ocampo, C. 17 Okano, Y. 14 Olson, C. 13 Ortigosa, D. 15 Owens, B. 10 Pankow, D. 10 Parsay, K. 1 Patel, H. 13 Patel, P. 16 Pelaez, J. 4, 19, 22 Peters, G. 20

Author Session Peterson, G. 2, 19 Petropoulos, A. 11 Phan, M. 5 Pitz, A. 4, 16 Policastri, L. 10 Poore, A. 7 Radice, G. 10 Reddy, S. 7 Rievers, B. 10, 14, 15 Rock, S. 9 Roemer, T. 18 Rogers, A. 15 Rubino, J. 20 Russell, R. 8, 11, 13 Sabol, C. 2, 15 Samiei, E. 9, 18 San-Juan, J. 15 Sanjurjo-Rivo, M. 22 Schaub, H. 1, 6, 9, 18, 19 Scheeres, D. 2, 15, 16, 21 Schlei, W. 11 Schoenmaekers, J. 11, 14 Senent, J. 17 Seubert, C. 1, 19 Sherrill, R. 1, 6 Shi, P. 5, 22 Shi, Y. 5, 9 Shimanjuntak, T. 5 Simo, J. 4 Sinclair, A. 1, 6, 13 Singh, N. 7 Slane, J. 20 Smith, D. 12 Spencer, D. 2 Stanley, R. 15 Starek, J. 9 Stevenson, D. 1 Stiles, L. 1 Strange, N. 8 Subbarao, K. 2 Sugimoto, Y. 5 Sun, J. 11 Sun, X. 6, 20 Takahashi, Y. 16 Tanygin, S. 3, 18 Tasker, F. 3 Tewari, A. 7 Thein, M. 18 Tichy, J. 1 Topputo, F. 5 Trushkyakov, T. 19 Trumbauer, E. 5 Tsuda, Y. 14

Author Session Turnowicz, M. 21 Udrea, B. 16, 20 Urrutxua, H. 4, 19, 22 Vallado, D. 6 Valli, M. 21 van der Ha, J. 10, 14, 15 Vaquero, M. 14 Vardaxis, G. 4 Villac, B. 4, 5 Vincent, M. 20 Vittaldev, V. 13 Wagner, S. 16 Wang, Y. 4 Wang, Z. 17 Watson, E. 20 Wawrzyniak, G. 12 Weisman, R. 21 Weiss, A. 19 Wen, C. 22 Wetterer, C. 2 Whalley, S. 2 Wibben, D. 12 Wie, B. 4, 12, 16 Wiesel, W. 5 Williams, J. 17 Williams, P. 2 Williams, T. 1, 20 Winkler, T. 16 Witzberger, K. 12 Wolfson, M. 20 Woo, P. 4 Woodard, M. 10, 20 Wright, C. 13 Wu, P. 11 Xin, M. 21 Xiucong, S. 6 Xu, S. 4, 9, 18, 22 Yang, Z. 11 Yin, J. 1, 6 Yutkin, E. 19 Zanetti, R. 3, 13 Zeng, X. 17 Zhang, H. 5 Zhao, Y. 5, 22 Zhu, M. 9 Zimmer, A. 11 Zin, A. 13


PAPERS SORTED BY TIME SLOT Day 1: January 30, 2012 Session Room Doc. # Author Title

8:00 1 Carolina A 100 Tichy Early Formation Design using a Geometrical Approach 2 Carolina B 109 Holzinger, et. al. Agile RSO Attitude Estimation Using Lightcurve Inversion and … 3 Calhoun 118 Linares, Crassidis Filtering Solution to Relative Attitude Determination Problem …

8:25 1 Carolina A 101 Parsay, et. al. Effects of Staggering Formation Maneuvers on the … 2 Carolina B 110 Holzinger, et. al. Delta-V Distance Object Correlation and Maneuver Detection with … 3 Calhoun 119 Lara, Ferrer Complete Closed Form Solution of a Tumbling Triaxial Satellite …

8:50 1 Carolina A 102 Healy, et. al. Formation Maneuver Planning for Collision Avoidance and … 2 Carolina B 111 Williams, et. al. Utilizing Stability Metrics to Aid in Sensor Network Management … 3 Calhoun 120 Hurtado Cayley Attitude Technique

9:15 1 Carolina A 103 Sherrill, et. al. A Lyapunov-Floquet Generalization of the Hill-Clohessy-Wiltshire … 2 Carolina B 112 Williams, et. al. Comparison of Two Single-Step, Myopic Sensor Management … 3 Calhoun 121 Hurtado Attitude Estimation in Higher Dimensions

9:40 - MORNING BREAK 10:05

1 Carolina A 104 Jones Optimal Reconfigurations of Coulomb Formations along Invariant … 2 Carolina B 113 Alfano Co-Orbiting Anti-Satellite Vulnerability 3 Calhoun 122 Hurtado Linear Solutions to Single Instance Position and Attitude Estimation

10:30 1 Carolina A 105 Stiles, et. al. Effective Coulomb Force Modeling in a Space Environment 2 Carolina B 115 Henderson, et. al. Inverse Problem Formulation Coupled with Unscented Kalman... 3 Calhoun 123 Lim, Tasker Analysis and Comparison of Rate Estimation Algorithms …

10:55 1 Carolina A 106 Stevenson, et. al. Multi-Sphere Modeling for Electrostatic Forces on Three-Dimensional … 2 Carolina B 116 Gangestad, et. al. Small Satellite Missions for Debris Tracking and Mitigation 3 Calhoun 125 Johnson, et. al. Autonomous Spacecraft Attitude Resource Sharing

11:20 1 Carolina A 107 Bae, Kim Analysis on Spacecraft Formation Flying in Elliptic Reference Orbits 2 Carolina B 117 Linares, Crassidis Inactive Space Object Shape Estimation via Astrometric and … 3 Calhoun 125 Zanetti, et. al. Novel Multiplicative Unscented Kalman Filter for Attitude Estimation

11:45 1 Carolina A 108 Yin, Han Comparison and Application Analysis of Classical Relative Motion

Models 3 Calhoun 126 Tanygin Projective Geometry of Attitude Parameterizations with Applications …

LUNCH 13:30

4 Carolina A 127 Bombardelli, et. al. Earth Delivery of a Small NEO with an Ion Beam Shepherd 5 Carolina B 135 Guzzetti, Lavagna Invariant Manifolds to Design Scientific Operative Orbits in the … 6 Calhoun 144 Lee, Mortari Circular Lattice String-of-Pearls Constellations for Radio … 7 Colonial 153 Carter, Humi Necessary Conditions for Optimal Impulsive Rendezvous in a …


January 30, 2012 (continued) Session Room Doc. # Author Title

13:55 4 Carolina A 128 Pitz, Vardaxis, et. al. Conceptual Design of Planetary Defense Technology … 5 Carolina B 136 Anderson Approaching Moons from Resonance via Invariant Manifolds 6 Calhoun 145 Draim, et. al. Common-Period Four-Satellite Continuous Global Coverage … 7 Colonial 154 Carter, Humi Existence and Sufficiency Conditions for Optimal Impulsive …

14:20 4 Carolina A 129 Hernandez, Barbee Design of Spacecraft Missions to Test Kinetic Impact for Asteroid … 5 Carolina B 137 Mingotti, et. al. Attainable Sets in Space Mission Design: A Method to Define Low … 6 Calhoun 146 Cui, Sun, et. al. Optimization of Hybrid Orbit Constellation Design for Space-Based … 7 Colonial 155 Bai, Junkins Modified Chebyshev-Picard Iteration Methods for Station-Keeping …

14:45 4 Carolina A 130 Simo, McInnes Feedback Stabilization of Displaced Periodic Orbits: Application to … 5 Carolina B 138 Sugimoto, et. al. Efficient Trajectory Correction for L2 Halo-Orbit Transfer using … 6 Calhoun 147 Davis, Mortari Reducing Walker, Flower, and Streets-of-Coverage Constellations to ... 7 Colonial 157 Reddy, Tewari Optimal Aeroassisted Orbital Transfer with Time Linear Control

15:10 - AFTERNOON BREAK 15:35

4 Carolina A 131 Haro, et. al. Dynamical Characterization of 1:1 Resonance Crossing Trajectories at … 5 Carolina B 139 Phan, Shi, et. al. Discrete-Time Bilinear Representation of Continuous-Time Bilinear … 6 Calhoun 148 Yin, Han Perturbation Effects on Elliptical Relative Motion Based on Relative … 7 Colonial 158 Hull, Harris Optimal Solutions and Guidance for Quasi-planar Ascent over a …

16:00 4 Carolina A 132 Furfaro, et. al. Close Proximity Asteroid Operations Using Sliding Control Modes 5 Carolina B 140 Trumbauer, Villac Expanding Transfer Representations in Symbolic Dynamics for … 6 Calhoun 149 Sinclair, et. al. Review of the Solutions to the Tschauner-Hempel Equations for … 7 Colonial 159 Singh, et. al. Space Object Maneuver Detection via a Joint Optimal Control and …

16:25 4 Carolina A 133 Wang, Xu Fourth-order Gravity Gradient Torque of Spacecraft Orbiting Asteroids 5 Carolina B 142 Wiesel A Theory of Low Eccentricity Satellite Motion 6 Calhoun 151 Hogan, Jasch Three-Dimensional Linear Stability Analysis of Spinning Three-Craft …

16:50 4 Carolina A 134 Woo, Misra On the Planar Motion in the Full Two-Body Problem 5 Carolina B 143 Zhang, Yushan, et.al. Two-Point Boundary Value Problem of the Relative Motion 6 Calhoun 152 Allgeier, Erwin, et.al. Velocity Extrema in Spacecraft Formation Flight

END OF SESSION FOR THE DAY


Day 2: January 31, 2012 Session Room Doc. # Author Title

8:00 8 Carolina A 162 Lantukh, et. al. Automated Inclusion of V-Infinity Leveraging Maneuvers in … 9 Carolina B 168 Samiei, et. al. Delayed Feedback Attitude Control Using Neural Networks and …

10 Calhoun 176 McLaughlin, et. al. Effects of High Frequency Density Variations on Orbit Propagation 8:25

8 Carolina A 163 Martinusi, Gurfil Closed-Form Solutions for Open Orbits Around an Oblate Planet 9 Carolina B 169 Burton, et. al. A New Method for Simulating the Attitude Dynamics of Passively …

10 Calhoun 177 Nayak End-of-Life Procedures for Air Force Missions: Orbital Debris … 8:50

8 Carolina A 164 Heiligers, et. al. Design of Optimal Transfers Between North and South Pole-Sitter Orbits 9 Carolina B 170 DeSouza, et. al. Design of Satellite Control Algorithm Using the State-Dependent …

10 Calhoun 178 Lebois, et. al. Extended Mission Maneuver Operations for the Interstellar Boundary … 9:15

8 Carolina A 165 Landau, et. al. Efficient Lunar Gravity Assists for Solar Electric Propulsion Missions 9 Carolina B 171 Munoz, Leve Artificial Potential Steering for Angular Momentum Exchange Devices

10 Calhoun 179 De Florio, et. al. Flight Results of the Precise Autonomous Orbit Keeping Experiment … 09:40 - MORNING BREAK

10:05 8 Carolina A 166 Krishnan Global Optimization Techniques for Deep Space Trajectory … 9 Carolina B 172 Shi, Longman Converting Repetitive Control Robustification Methods to Apply …

10 Calhoun 180 Rievers, et. al. Numerical Prediction of Satellite Surface Forces with Application to… 10:30

8 Carolina A 167 Missel Optimization of Debris Removal Path for TAMU Sweeper 9 Carolina B 173 Guan, Xu De-orbit Attitude Dynamics and Control of Spacecraft with Residual …

10 Calhoun 181 Owens, et. al. Mass Ejection Anomaly in Lissajous Orbit: Response and Implications … 10:55

9 Carolina B 174 Zhu, et. al. A Computational Efficient Suboptimal Algorithm for Dynamic Thruster.. 10 Calhoun 182 Owens, et. al. Optimizing ARTEMIS Libration Point Orbit Stationkeeping Costs …

11:20 9 Carolina B 175 Gui, Guan, et. al. Analysis of Small-Time Local Controllability of Spacecraft Attitude …

10 Calhoun 183 Marchese, et. al. Optimizing Solar Radiation Coefficient as a Solve-For Parameter for … LUNCH

13:30 11 Carolina A 184 Grover, Andersson Optimized Three-Body Gravity Assists and Manifold Transfers in … 12 Carolina B 191 Gaudet, Furfaro Adaptive Pinpoint and Fuel Efficient Mars Landing Using … 13 Calhoun 198 Zanetti, D'Souza Dual Accelerometer Usage Strategy for Onboard Space Navigation

13:55 11 Carolina A 185 Campagnola, et. al. Tisserand-Leveraging Transfer and Their Application to Real Missions 12 Carolina B 192 Witzberger, Smith Design and Assessment of Open-loop Variable Coast Time Guidance … 13 Calhoun 199 Olson, et. al. Expected Navigation Flight Performance for the Magnetospheric …

14:20 11 Carolina A 186 Zimmer, et. al Utilization of Sun-Earth Libration Points as Staging Locations for … 12 Carolina B 194 Wawrzyniak, Howell Flight-Path Control for Solar Sail Spacecraft 13 Calhoun 200 Gehly, et. al. Minimum L1 Norm Orbit Determination Using A Sequential …


January 31, 2012 (continued) Session Room Doc. # Author Title

14:45 11 Carolina A 187 Nakamiya, et. al. Preliminary Study of the Transfer Trajectory from the Moon to the … 12 Carolina B 195 Wibben, Furfaro Integrated Guidance and Attitude Control for Pinpoint Lunar … 13 Calhoun 201 Karimi, Mortari Orbit Determination Based on Variations of Orbital Elements

15:10 - AFTERNOON BREAK 15:35

11 Carolina A 188 Hsiao, et. al. Circular Restricted Three-Body Problem with Photonic Laser Propulsion 12 Carolina B 196 Hawkins, et. al. Waypoint-Optimized Zero-Effort-Miss/Zero-Effort-Velocity … 13 Calhoun 202 Patel, Lovell, et. al. Relative Navigation for Satellites in Close Proximity Using Angles …

16:00 11 Carolina A 189 Duffy, Chichka Canonical Perturbation Theory for the Elliptic Restricted-Three … 12 Carolina B 197 Hawkins, et. al. Zero-Effort-Miss/Zero-Effort-Velocity (ZEM/ZEV) Feedback Guidance 13 Calhoun 203 Casotto, et. al. Preliminary Assessment of Orbit Restitution Capability of a …

16:25 11 Carolina A 190 Schlei, Howell A Visual Analytics Approach to Preliminary Trajectory Design 13 Calhoun 204 Vittaldev, et. al. Second-Order Kalman Filter Using Multi-Complex Step Derivatives

END OF SESSION FOR THE DAY


Day 3: February 1, 2012 Session Room Doc. # Author Title

8:00 14 Carolina A 205 Kawakatsu, et. al. An Orbit Plan toward AKATSUKI Venus Re-encounter and Orbit

Injection 15 Carolina B 213 Condurache A Closed Form Solution of the Two Body Problem in Non-Inertial … 16 Calhoun 221 Udrea, et. al. Imaging LIDAR Mapping of an Asteroid for Autonomous Operations

8:25 14 Carolina A 206 Kawakatsu Practical Design of 3D Phasing Orbit in Lunar Transfer Trajectory 15 Carolina B 214 Jones, Anderson A Survey of Symplectic and Collocation Integration Methods for Orbit … 16 Calhoun 222 Udrea, et. al. Sensitivity Analysis of the Touchdown Footprint at (101955) 1999 RQ36

8:50 14 Carolina A 207 Boutonnet, et. al. Mission Analysis for the JUICE Mission 15 Carolina B 215 McMahon, Scheers Appropriate Modeling of Solar Radiation Pressure Effects on … 16 Calhoun 223 Udrea, et. al. Refined Gravity Determination at Small Bodies through Landing Probes

9:15 14 Carolina A 208 Kato, et. al. Sensitivity Analysis of Non-Gravitational Perturbations on a Mercury … 15 Carolina B 216 Bradley, et. al. Assessment of a New Numerical Integration Technique in Astrodynamics 16 Calhoun 224 Takahashi, Scheeres Surface Gravity Fields for Asteroids and Comets 9:40 - MORNING BREAK

10:05 14 Carolina A 210 Herman, Noomen Preliminary Mission Design for a Far-Side Solar Observatory using … 15 Carolina B 217 Rogers, et. al. Analytical Stability Analysis of Displaced, Geostationary Orbits using … 16 Calhoun 225 Pitz, et. al. Preliminary Design of Hypervelocity Nuclear Interceptor Spacecraft …

10:30 14 Carolina A 211 Tsuda, et. al. On-Orbit Sail Quality Evaluation Utilizing Attitude Dynamics of … 15 Carolina B 218 San-Juan, et. al. Comparison of Delaunay Normalization and the Krylov-Bogoliubov … 16 Calhoun 226 Winkler, et. al. Target Selection for a Planetary Defense Technology Demonstration …

10:55 14 Carolina A 212 Chappaz, et. al. Transfer of Impact Ejecta Material from the Surface of Mars to Phobos … 15 Carolina B 219 Kato, et. al. Detailed Analysis of Solar and Thermal Accelerations Acting on Deep-… 16 Calhoun 227 Bombardelli, Carnelli The SIROCO Asteroid Deflection Demonstrator

11:20 15 Carolina B 220 Cefola, et. al. Extension of the DSST Semi-analytical Theory Architecture 16 Calhoun 228 Nayak, Bogdan Validation and Application of a Preliminary Target Selection Algorithm... LUNCH

13:30 17 Carolina A 230 Wang Integrated Launch Window Analysis and Precision Transfer Trajectory … 18 Carolina B 237 Nazari, et. al. Attitude Stabilization Using Nonlinear Delayed Actuator Control with … 19 Calhoun 245 Armellin, et. al. An Orbital Conjunction Algorithm Based on Taylor Models

13:55 17 Carolina A 231 Hudson,

Komanovsky Iterative Model Refinement for Orbital Trajectory Optimization

18 Carolina B 238 Liu, et. al. Backstepping Simple Adaptive Attitude Control and Disturbance … 19 Calhoun 246 Bombardelli, et. al. Relative Dynamics and Control of an Ion Beam Shepherd Satellite


February 1, 2012 (continued) Session Room Doc. # Author Title

14:20 17 Carolina A 232 Martinusi, Gurfil New Orbit Propagator for Motion Around an Oblate Planet 18 Carolina B 239 Melton Hybrid Method for Constrained Time-Optimal Spacecraft … 19 Calhoun 247 Coppola Including Velocity Uncertainty in the Probability of Collision Between …

14:45 17 Carolina A 234 Zeng, et. al. Optimal Solar Sail Trajectory Analysis for Interstellar Missions 18 Carolina B 240 Cavalieri, et. al. Laboratory Experiments for Position and Attitude Estimation using the … 19 Calhoun 248 Coppola Evaluating the Short Encounter Assumption of the Probability of … 15:10 - AFTERNOON BREAK

15:35 17 Carolina A 235 de Dilectis, Mortari Optimal Use of Perturbations for Space Missions 18 Carolina B 241 Tanygin Projective Geometry of Attitude Parameterizations with Applications … 19 Calhoun 249 Healy Lambert Targeting for On-Orbit Delivery of Debris Remediation Dust

16:00 17 Carolina A 236 Williams, et. al. Recent Improvements to the Copernicus Trajectory Design and … 18 Carolina B 242 Atkins, Henderson Under-Actuated Moving Mass Attitude Control for a 3U Cubesat Mission 19 Calhoun 250 Baldwin, et. al. Spacecraft Debris Avoidance Using Positively Invariant Constraint …

16:25 18 Carolina B 243 Knutson, Howell Using Kane's Method to Incorporate Attitude Dynamics in the Circular … 19 Calhoun 251 Peterson Target Identification and Delta-V Sizing for Active Debris Removal …

16:50 18 Carolina B 244 Roemer, et. al. Using the Magnetospheric Multiscale (MMS) TableSat IB for the … 19 Calhoun 252 Jasper, et. al. Tethered Tug for Large Low Earth Orbit Debris Removal END OF SESSION FOR THE DAY


Day 4: February 2, 2012 Session Room Doc. # Author Title

8:00 20 Carolina A 253 Sun, et. al. APCHI Technique for Rapidly and Accurately Predicting Multi … 21 Carolina B 260 DeMars, Jah Initial Orbit Determination via Gaussian Mixture Approximation of … 22 Calhoun 267 Garber Application of the Generalized Transfer Equation for Mission Planning

8:25 20 Carolina A 254 Mann, et. al. Landsat Data Continuity Mission (LDCM) Ascent and Operational … 21 Carolina B 261 DeMars, et. al. Methods for Splitting Gaussian Distributions and Applications within … 22 Calhoun 268 Sanjurjo-Rivo, et. al. Asymptotic Solution for the Two Body-Problem with Low-Thrust

8:50 20 Carolina A 255 Williams Launch Window Analysis for the Magnetospheric Multiscale Mission 21 Carolina B 262 Majji, et. al. Solution of the Liouville’s Equation for Keplerian Motion: Application … 22 Calhoun 269 Urrutxua, et. al. Frozen Orbits for Scientific Missions Using Rotating Tethers

9:15 20 Carolina A 256 Vincent Two Geometric aspects of the Orbiting Carbon Observatory Mission 21 Carolina B 263 Fujimoto, Scheeres Non-Linear Propagation of Uncertainty with Non-Conservative Effects 22 Calhoun 270 Liu, Xu Backstepping Adaptive Control for Flexible Space Structure with … 9:40 - MORNING BREAK

10:05 20 Carolina A 257 Anderson, et. al. Static Highly Elliptical Orbits using Hybrid Low-Thrust Propulsion 21 Carolina B 264 Valli, et. al. Nonlinear Management of Uncertainties in Celestial Mechanics 22 Calhoun 272 Wen, et. al. Solving and Analyzing Relative Lambert's Problem through …

10:30 20 Carolina A 258 Watson, Lovell Sun-Synchronous Orbit Slot Architecture: Analysis and Development 21 Carolina B 265 Turnowics, et. al. Quadrature Methods for Orbit Uncertainty Propagation under Solar … 22 Calhoun 273 DiPrinzio Three Lambert Formulations with Finite, Computable Bounds

10:55 20 Carolina A 259 Armstrong, et. al. Preliminary Design of a Mini-Satellite for Drag Estimation (MinDE) END OF SESSION FOR THE DAY


RECORD OF MEETING EXPENSES

22nd AAS/AIAA Space Flight Mechanics Meeting Francis Marion Hotel, Charleston, South Carolina

29 January-2 February 2012

Name:______________________________ Organization: ______________________________

Category Early Registration (through 10 Jan 2012)

Regular Registration

Full - AAS or AIAA Member $450 $500 Full - Non-member $550 $600 Retired* $125 $175 Student* $125 $175

Registration Fee: ___________________

Conference Proceedings (Hard Cover)1

___ @ $250 (domestic) ___________________

___ @ $300 (international) ___________________

Extra CD Conference Proceedings1 ___ @ $45 ___________________

Special Event Guest Ticket ___@ $50 ___________________

TOTAL: ___________________

Recorded by: ________________________________

1 Digital Proceedings on Compact Disk (CD) are provided after conference at no extra cost for full registrants


CONFERENCE SATISFACTION SURVEY The organizing committee welcomes your comments. Please fill out this questionnaire and return it to the registration desk or to a session chair. Thank you!

General

Please tell us if you registered as:

Student Retired Member Non-member

Please tell us if you think the conference was well organized.

Very Poorly Poorly Average Good Very Well

Please tell us if you think that the conference information site was adequate in presenting all necessary information.

Very Poor Poor Average Good Excellent

Approximately how many conference of this type do you attend annually?

Maybe 1 1-2 3-4 4-5 >5

Where do you think our conference fee typically falls in terms of value?

1 2 3 4 5

Unsatisfied Satisfied

Registration

Overall, how satisfied were you with the online registration process?

1 2 3 4 5


Overall, how satisfied were you with the online abstract/paper submission process?

1 2 3 4 5


How much does the registration fee influence your decision or ability to regularly attend these conferences?

1 2 3 4 5


Venue

Overall, how satisfied were you with the conference location?

1 2 3 4 5


Technical Content

How satisfied were you regarding the overall technical content?

1 2 3 4 5


How satisfied were you with the printed materials received?

1 2 3 4 5


How do you feel about the publisher’s 20-page limit on papers?

Too Long Just Right Too Short Don’t Care

How do you feel about having 72 hours before the conference to download/print preprints?

Too Long Just Right Too Short Don’t Care

How many presentations did you attend?

<10 10-20 21-30 31-40 >40

What meeting length ideally matches your ability to attend?

<3 days 3 days 3.5 days 4 days

If your ideal meeting length cannot accommodate all accepted papers, which do you prefer most?

Increase Hold More Than Shorten Reject Meeting 3 Concurrent Presentation More Length Sessions Length Papers

Social Events

How satisfied were you with the receptions?

1 2 3 4 5


How satisfied were you with the offsite event?

1 2 3 4 5


How do you feel about how many social events are held?

Too Few Just Right Too Many Don’t Care


Additional Survey Comments

General

_______________________________________________________________________________________________________

_______________________________________________________________________________________________________

_______________________________________________________________________________________________________

_______________________________________________________________________________________________________

_______________________________________________________________________________________________________

Registration

_______________________________________________________________________________________________________

_______________________________________________________________________________________________________

_______________________________________________________________________________________________________

_______________________________________________________________________________________________________

_______________________________________________________________________________________________________

Venue

_______________________________________________________________________________________________________

_______________________________________________________________________________________________________

_______________________________________________________________________________________________________

_______________________________________________________________________________________________________

_______________________________________________________________________________________________________

Technical Content

_______________________________________________________________________________________________________

_______________________________________________________________________________________________________

_______________________________________________________________________________________________________

_______________________________________________________________________________________________________

_______________________________________________________________________________________________________

Social Events

_______________________________________________________________________________________________________

_______________________________________________________________________________________________________

_______________________________________________________________________________________________________

_______________________________________________________________________________________________________

_______________________________________________________________________________________________________

february 2, 2012 charleston, south carolina - spaceflight · 22nd aa s /aiaa space flight mechanics...

Documents