t revolutionary aerospace systems concepts – academic...

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University of MarylandSpace Systems Design

Revolutionary Aerospace Systems Concepts– Academic Linkage

ConferenceMay 18-21, 2003

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Potential Problem• Space station manned with a 3 member crew• Critical failure requires an EVA• Today’s solution to fix problem:

– Astronaut Emergency EVA• Requires 3 crew members

– First maneuvers Remote Manipulator System (RMS) to location» Low speed/ lengthy process - Loaded: 0.06m/sec (2.4in/sec)» Immediate operation initiation required

– Second and Third must head to airlock for pre-breathing» Time required: 4 hours» One crew member maneuvered at problem site by RMS» One crew member is a free floater

• Leaves no one to operate the station

Example Scenario: Intelsat rescue mission (3 crew out for EVA)

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Today’s Solution• Limitations to this solution

– RMS maneuvering time if far away from problem area– Astronaut pre-breathing time– Use of all crew members– No one left to take care of space station– Limited time available for the EVA

• Potential Improvements– Not using all crew members– Minimal preparation and travel time– Fix problem faster– Maximize work time

Future solution: a system that combines human androbotic interfaces to improve all current systems

ILC Dover

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Space Construction & Orbital Utility Transport• Proposed element of the Orbital

Aggregation & SpaceInfrastructure Systems (OASIS)program

• Designed to operate withproposed Gateway Station at theEarth-Moon L1 Point

• Closed-cabin atmosphericsystem for EVA

• SCOUT System:– Two SCOUT pods– Docking Module (DM)– eXtended Mission Pallet (XMP)

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Overview• Design Requirements/ Constraints• SCOUT Systems Summary• Mission Planning• Support Infrastructure• Task Requirements• Interior/ Exterior Features• Life Support and Human Factors• Structures/ Thermal• Propulsion/ RCS• Power/ Avionics• Costing• EVA Systems Comparison• Conclusions

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Level One Design Requirements• Vehicle requirements

– Operate from the L1 Gateway system– Interact with worksite using hands and dexterous manipulators– Attach to and control the worksite (reference worksite: HST)– Provide low-contamination propulsion system for use in contamination-critical

regions– Provide for on-board human control, on-board autonomous control,

supervisory control, and teleoperation– Single-interface replenishment at the docking port capable of single-person

checkout and refurbishment between each use (time < 1 hour)– All safety-critical systems shall be two-fault tolerant– Support extended missions

• Capability requirements– Provide capability to operate at International Space Station with minimal

modifications– Standard operational capabilities shall meet or exceed EVA capabilities

demonstrated on HST and ISS• System requirements

– Design in accordance with NASA Standard JSC-28354, Human-RatingRequirements

– Minimum TRL of 3 by Jan. 1, 2005 and minimum TRL of 6 by Jan.1, 2008– Launch on US launch vehicles currently planned to be operational in 2005

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SCOUT Major Design Constraints• Task/human arm interaction• Worksite attach/control• Zero pre-breathe• Shirt-sleeve operation• Operating Pressure: 8.3 psi• RMS attach fitting• International Berthing and

Docking Mechanism (IBDM)with internal hatch opening

• Escape system placement

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Basic SCOUT Dimensions

0.340.82

1.85

1.50

0.75

r = 0.33

0.70

2.00

0.87

Rear ViewSide View Bottom View

All dimensions in meters

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Vehicle Mass/Power Breakdown

Total

Power, Propulsion,and Thermal

Avionics

Life Support andHuman Factors

Loads, Structures,and Mechanisms

System

91518502000

85633675

295190200

295235275

240796850

Power (W)Actual Mass (kg)Allotted Mass (kg)

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Trajectory to L1

1. Test Mission at ISS2. Solar Electric Propulsion (SEP) stage travels with SCOUT system3. SEP travels with Gateway on autonomous spiral to L14. Docking Module (DM) and SCOUT are berthed with Gateway5. Crew Transfer Vehicle (CTV) brings first six month crew

Lin, Frank. Lunar L1 Gateway & SEP Design Briefing. 02 Nov 2001.

1

5

32

4

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Docking Module• Three International Berthing and Docking Mechanisms

(IBDMs)– Two are used for SCOUT pods– One is used for attachment to Gateway

• Storage capabilities– Six months of propellant– Spare batteries– Human suit arms and gloves

• Self-sufficient power– Triple junction crystalline solar arrays

• Is = 1394W/m2, ρpower = 250W/kg, ηeff = 40%

• Surface area = 4.5m2, mass = 10kg• Generates 5kW

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Resupply Plan• SCOUT vehicles are designed to automatically resupply fuel,

atmospheric consumables, and power after each sortie duringDM attachment

• Docking Module resupply– Every six months for a nominal mission model– Every three months for an aggressive mission model

• OASIS infrastructure vehicles– Crew Transfer Vehicle (CTV) rotates crew and carries human

consumables every six months, and life support every two years– Hybrid Propellant Module (HPM) resupplies LOX and LH2 every

six months– Chemical Transfer Module (CTM) ferries payloads short

distances, provides a high impulse transfer from LEO to L1, and isused for extended missions

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SCOUT System Reliability• Cumulative probability of safe crew return over the

life of the program must exceed 0.99• Assumptions:

– Pod failure will force bailout of astronaut– Astronaut must rely on independent propulsion system for

safe return to Gateway– Escape components consist of a Bailout System (BS) and

Propulsion Equipped Bailout System (PEBS)

• After examining several combinations of pods andescape systems, it was determined that two podseach with a PEBS provided the required reliability

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Nominal and Aggressive Missions• Nominal six-month mission consists of 30 sorties between both pods

– Eleven hours spent in the pod for eight hours of work– Total SCOUT hours for two pods: 240 working hours and 330 hours inside

the pod– Pod end of life occurs at 20 years

• Aggressive mission model doubles sortie and resupply rates

Break 2 – Lunch05:15:00

Work Period 203:15:00

Break 103:00:00


Attach to worksite00:30:00

Travel to worksite00:00:00

ActivityStart TimeExample Sortie

Total Sortie Time11:00:00

Dock to Gateway10:30:00

Travel to Gateway10:00:00


Break 307:45:00


ActivityStart Time

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Extended Duration Missions• Several possible scenarios

– Geostationary satellite servicing– Lunar orbit– Mars mission– ISS servicing

• Example mission model from L1 to lunar orbit– SCOUT is not designed to land on the lunar surface– CTV stack carries SCOUT and XMP that transports

propellant and consumables– Approximate travel time of 23 hours– CTV acts as lifeboat in the case of an emergency– Tasks are completed in a 16 hour workday which includes

work time and breaks

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eXtended Mission Pallet (XMP)• Supports off-site extended sorties:

– Attaches between SCOUT and tow-vehicle– Remains attached to tow-vehicle while SCOUT performs worksite

operation– Provides off-site refueling/recharging– Shirt-sleeve atmosphere allows passage from SCOUT to tow-

vehicle• Mission Flexibility:

– May be tailored to particular extended mission– IBDM permits docking with any OASIS vehicle

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Task Requirements• Meet or exceed EVA capabilities demonstrated in International

Space Station (ISS) and Hubble Space Telescope (HST)operations– Orbital Replacement Units (ORUs)– Large truss segments– Modules– Flexible materials– Fragile materials

• Assembly of a 25m infrared telescope– Truss segments– Fragile materials– Refueling

• Lunar lander, CTV, CTM, HPM, SEP, and Gateway stationmaintenance– ORUs– Fragile materials

• Service on other SCOUT pods, the DM, and XMP– ORUs– Fragile materials

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Dexterous Manipulator Design• Task arms are modeled after 8-DOF Ranger Telerobotic

Shuttle Experiment arm– Trade study found two arms to be the best choice

• One arm did not provide the ability to grasp the hardware beingremoved while removing bolts and latches

• Three arms brought a concern about the interference of the arms witheach other and with the human arms due to intersecting workenvelopes

– Uses interchangeable end effectors for task completion• Maximum of eight end effectors on SCOUT• End effectors will be predetermined prior to sortie

• Grapple arm is a modified version of the task arm– Has a pitch joint at the wrist and is longer than the task arm– Uses either a universal gripping end effector or a foot restraint

interface end effector– Laser rangefinder is mounted on the grapple arm elbow

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Example End Effector Set• Bare Bolt Drive (BBD) end effector

– Drive bolts for the insertion and extraction of ORUs and theassembly of truss structures

• Parallel Jaw Mechanism (PJM) end effector– ORU grasping interfaces referenced from the ISS Robotic Systems

Integration Standards (JSC-37996)– Different “fingers” depending upon the grasping surface– Hand-over-hand (HOH) fingers

• Conceptual design that has the ability to grip several different itemswith set dimensions and shapes

• Found on the grapple arm and task arms• Used for gripping the worksite and non-thrusting maneuvers

• Microconical end effector (MEE)– ORU grasping interfaces referenced from the ISS Robotic Systems

Integration Standards (JSC-37996)– Used to grip microconical interfaces and micro fixtures found on

ORUs less than 600kg• End effectors are stored on tool posts found on both the sides

and underneath SCOUT

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Comparison of Tool Sets

PJMRigidizing tether or personal foot restraintAttach to worksite*

PJMGloved handsPull and rotateswitches

PJMGloved handsUsepliers/wrenches

BBD/PJMPistol grip tool or power ratchet toolDrive a gearPJMGloved handsTighten a tetherBBDEssex ratchet or ISS ratchetUse a ratchetPJMGloved handsTighten a latch

PJMGloved hand with specialized toolMate/demateconnectors

PJMGloved handsHold a handle

BBDRight angle drive with sockets and multi-setting torque limiter or cheater barDrive bolts

Robotic ToolHuman ToolActivity

O’Hara, John M. et al. Extravehicular Activities Limitations Study. ( all except * )

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Exterior Features

RMS Grapple FixtureEscape System

IBDM

Star Tracker

Ka-Band

UHF

Radiator

Grapple Arm

Laser Rangefinder

Radiator

Nitrogen QuadHydrazine

Triad

Single Hydrazine

Handrail

Helmet/Heads-Up-Display(HUD)

Human AX-5 Arms

Tool Posts

ExternalCamera

Task Arms

Mini-Workstation

Front View Rear View

Lights ExternalCamera

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Secondary Egress / Bailout (SHEEP)

Viewing window

Hand Controller

Spacesuit Arms

SAFER-typepropulsion

system

Softexpandable

body

• Current bailout design is anexternally expandable hybridspacesuit, to be known as theSCOUT Hybrid Expandable EscapePod (SHEEP)

– Hybrid design of the current NASAbailout ball, and the past Rockwellconceptual design of the RibStiffened Expandable EscapeSystem (RSEES)

– Escape Pod would be containedwithin a canister that is located onthe outside of SCOUT

– In the event of an emergency, thecrewmember would deploy thespacesuit, climb in, close the suit,and detach from SCOUT

– Allows the crewmember minimal useof their hands in order to control thepropulsion device and translatealong EVA handrails

– Provide crew member with 3 hrs ofemergency air (back-up fromSCOUT)

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Contoured Hull• The contoured torso hull will be place on the relative front of SCOUT and be

aligned with the relative top of the vehicle• The design of the torso hull was based off the torso of other hard suits, more

precisely the JSC Mark III and Ames AX-5• Combination of two rotary seals will be used to accommodate the varying

shoulder berths and sizes of the wide range of users• Current design for spacesuit arms

and gloves• Modeled after the NASA Ames

AX-5 suit arms• Shuttle Transport System

(STS) Extravehicular MobilityUnit (EMU) gloves

• Development of the AX-5 suit isbased on the capability of providingthe crewmember with a zero pre-breathe mission through anoperating pressure of 8.3psi

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Internal Layout

Front View Rear View Side View

Foot restraint locations

StorageBox

InternalCamera

EscapeHatch

PressureControl

CO2/AirSystem

WasteCollectionSystem

HandControllers

Computers

Touch ScreenMonitors

KeyboardFire Extinguisher

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Internal Volume Constraints• Major volume requirements designed

into the cabin layout

– Minimal volume required toaccommodate a 95% American male

• 0.72m x 0.71m x 0.172m• Internal components placed around

this volume

– Minimal volume required for acontrolled tumble

• Sphere with 1.22m diameter• Needed to flip over within SCOUT

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Worksite Interaction• Heads-Up Display (HUD)

– Used for display of pertinent informationdealing with

• Flight control• Robotic control• General SCOUT system

• Hand Controllers– Two 3-DOF controllers used for

translation and rotation control of• Manual flight• Operation of the task arms

• AX-5 Arm and Glove Sensors– Used to control task arms– Activated/deactivated by voice command

• Voice Recognition– System utilizes pre-allocated

communications hardware with thecomputers to process voice commands

– Allows for both coarse and fine control ofdexterous manipulators

HUD

Hand Controllers

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Crew Member Orientation• Foot Restraints – Floor

– Operation used for• AX-5 suit arm task work• Glove Sensors• Voice activation

• Foot Restraints – Back Wall– Operation used for

• Hand controllers• Voice activation

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Command, Control, and Comm Station• Two Touch Screen Monitors

– 15in display– Mass: 7.3kg– Peak Power: 26W– Accepts both HDTV and

computer input– Primarily used as a

reconfigurable computer displayduring system monitoring andvideo communication

• Keyboard• Internal Camera

– Used for real-time videoconferencing

Comm Station

Touch Screen Monitors

KeyboardCamera

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Life Support Systems Flowchart

CabinPressureControl

Panel (PCP)

Air Tanks

Overboard Vent

Charcoal Bed Metox

Condensing HeatExchanger

Waterin

To Gateway

Waste WaterTank

WasteCollectionSystem

Waterout

57kPa (8.3psi)

43% O2 / 57% N2

20.7MPa(3000psi)

Filter

Legend:

- Air Systems - Vacuum - Gateway - Waste - Pumps - Fan

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Food, Water, and Waste• Food

– Nominal one meal per day on SCOUT– Nutrition requirements

• Protein: 150g/day• Carbohydrate: 350g/day• Lipids: 85g/day

• Water– 3.1kg (105oz) of water carried on board in a standard reusable

drink container

• Waste– Smaller version of Shuttle WCS

• Convenient• Use does not require deviation from nominal diet

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Atmosphere• Air Systems provides nominal 20.5 hours; 41 hours as absolute

maximum– One oxygen tank is emergency backup

• Operating pressure 57kPa (8.3psi), 43% O2 / 57% N2

• R = ppN2-bloodstream/Patm = 0.65 (zero pre-breathe)R Value for Various Nitrogen Partial Pressures of Stations Hosting SCOUT

2

Gateway:

ppN2 = 5.4, R = 0.65

ISS: ppN2 = 11.6,

R = 1.39

0

0.2

0.4

0.6

0.8

1

1.2

1.4

1.6

1.8

2

0 2 4 6 8 10 12 14 16ppN2

R

Acceptable below this lineIdeal below this line

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Overall Structural Design• Hexagonal Pressure Hull

– Load-bearing aluminum panelsincorporating Micrometeoroid (MM) andOrbital Debris (OD) protection

– Stringers to transfer panel loads andserve as hard attachment points forShuttle launching

• Outer Frame– Load-bearing aluminum panels with MM

and OD protection– House external tanks and electronics– Back panel hinged for Li-Ion Battery

replacement and Power Distribution Unit(PDU) servicing

• Main mechanisms– International Berthing and

Docking Mechanism (IBDM)– Dexterous Manipulators– Remote Manipulator System (RMS)

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Launch Vehicle Integration• Using Spacelab Logistics

Pallet (SLP) with 5 pointattachment:– 2 sill fittings ±X and ±Z

loads– 2 sill fittings ±Z loads– 1 keel fitting ±Y loads

• Other SCOUT, DockingModule (DM) and eXtendedMission Pallet (XMP)attached to pallet similarly

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Loading Configuration - Launch• Considered

– Major inertia loads• All components over 2kg considered• Components masses multiplied by shuttle launch loads

– X = 5.8g, Y = 4.85g, Z = 8.5g• Forces in 350N – 20kN range

– Pressure load• Pressurized at 101.3kPa (14.7psi)

• Not considered– Assumed smaller compared to

launch induced loads• Launch acoustics• Random launch vibration• Thermal variation

Z

Y

X

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Loading Configuration - Operation• Pressure

– Design load: 101.3kPa (14.7psi)(departing from ISS)

– Other loads: 62kPa (departing from Gateway), 57kPa(operating at worksite)

• Task arms– 2620N force, 374N-m bending moment, 52.2N-m torque– At shoulder mount, in best case position

• Grapple arm– 400N tensile force, 400N shear force, 1170N-m bending

moment and torque– At shoulder mount, from various worst case configurations

induced by task arm forces

• Human arms– 1140N force, max force exerted by 95% male upper arm in

space suit (NASA-STD-3000)– At shoulder mount of AX-5 arms

• Remote Manipulator System (RMS)– 890N, 20º off perpendicular to grapple shaft

(on back)

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Loading Configuration - Other• Worksite transfer

– Thrusters forces on the order of 1N and 6N

• Docking– IBDM docking loads ~120N

• Maximum docking velocity = 0.06m/s• Assumed 1 second impulse load

– Berthing, if using RMS• Already accounted for in operational loading configuration

• Quantification of loads resulted in analysis of onlytwo configurations– Shuttle launch / abort– Worksite operation

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Micrometeoroid and Orbital Debris Protection• Definitions of Terms

– Micrometeoroid = 10-18 – 1.0gm in mass [NASA PD-EC-1107]

• Natural origin– Orbital/Space Debris exist below 2,000km altitude (LEO)

• Artificial objects• Requirement

– The design shall provide a minimum Probability of No Penetration (PNP)defined by:

• Bumper Wall (Outer Wall)– Aluminum 6061-T6– Thickness: 0.06cm

• Back-Up Wall (Inner Wall)– Aluminum 6061-T6– Spacing = 1.0cm– Thickness: minimum of 0.24cm required

Requirement for Space Shuttle Payload [NASA SSP-52005B]

A = exposed surface area (m2)Y = exposure time (year)PNP=0.9999AY

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Radiation Exposure Limits• Assuming annual radiation exposure to Blood Forming Organs

(BFOs)– 50 allowable rem / 365 days = 0.14rem/day– (0.14rem/day) / (24hrs/day)

= 0.007 allowable rem/hr• Estimated total time in pod per astronaut

– (6mo)(15days/6mo)(13hrs/day) =195hrs• Total allowed radiation exposure

– (0.007rem/hr)(195hrs) = 1.4 allowable rem• With 4g/cm2 aluminum shielding data from STS-89

– 62 days exposure = 0.6% increase in excess fatal cancer• With 4g/cm2 aluminum shielding data from SCOUT

– 15 days exposure ~ 0.2% increase in excess fatal cancer≪ 3% lifetime limit

• Assuming Gateway radiation levels ≤ SCOUT180 days exposure ~1.74% increase in excessfatal cancer (3% lifetime limit)

*Radiation limits gathered from NASA-STD-3000

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Radiation Protection• Panels that need extra radiation protection

– Front, extra 3.23g/cm2

– Left Front, extra 2.42g/cm2

– Right Front, extra 2.23g/cm2

• These numbers are to meet the requirement of having radiationprotection of 4g/cm2

• The current plan for SCOUT for the Gateway missions is tohave these panels as extra aluminum panels

• This increases the margin of safety (MOS) for those panels ofthe spacecraft

• All other areas of the spacecraft have enough mass andsurface area of other components that no extra radiationprotection is required

• With future innovation in radiation protection, the front 3 panelscan be outfitted with any material that will meet the abovecriteria

• Also for missions that may require more stringent radiationrequirements, SCOUT can have panels added in locationsrequiring more protection

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Calculations Overview• Calculations were done to determine the thickness of

the SCOUT panels• Three different situations were analyzed

– Pressurization loading– Operational loading– Launch loading

• Axial direction• Shear direction

• Each system was optimized to the minimumthickness based on the lowest non-negative marginof safety (MOS) that was acceptable for allrequirements

• Micrometeoroid, orbital debris and radiationprotection were taken into account for thesecalculations

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Panel StructureFactor of Safety – 2.0 : Primary

Axial LaunchLoading0.047275132Alum 6061-

T626.3Right Front7

RadiationProtection4.14275136Alum 6061-

T633.6Right FrontExtra8


T621.9Left BackPressure6


T636.5Left FrontExtra5


T623.5Left Front4


T648.6Front Extra3

OperationalLoading0.042275124Alum 6061-

T611.3Front2


T613.7Top1

Based OnMOSYield Stress(MPa)

DesignLoad (MPa)MaterialMass

(kg)Name#

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Panel StructureFactor of Safety – 2.0 : Primary

Axial LaunchLoading0.052275132Alum

6061-T611.3Left Back14


6061-T613.8BackPressure13


6061-T611.3Right Back12


6061-T626.5Bottom11

Not LoadBearingN/A275124Alum

6061-T619.4Back Panel10


6061-T621.9Right BackPressure9

Based OnMOSYield

Stress(MPa)

DesignLoad (MPa)MaterialMass

(kg)Name#

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Thermal Control• Interior Environment

– The interior of the pod, specifically thepressure hull, will be maintained thermallyby utilizing a series of different systems

• Heat Exchanger: transfer heat fromcirculating ‘cabin’ air to working fluid in heatpipe

• Heat Pipe: transport heat to radiator usingfreon via capillary action

• Radiator: radiate heat to space• Heater: trim temperature during colder

conditions• Battery Subsystem

– The batteries will be controlled thermally byan active radiator system

• Radiator: radiate heat generated frombattery packs using a system of coolingloops and a working fluid consisting of freon

• Pump: circulate freon through radiator• Insulation will be used to keep the fuel

tanks at nominal temperature with Multi-Layer Insulation (MLI)

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Propulsion Tanks• Requirements for tanks

0.0120.030.32Volume of the Tank (m3)

0.090.100.17Inner Radius (m)

272.227Max. Operating Pressure (Mpa)

NitrogenPressurant

HydrazinePropellant

NitrogenPropellant

Hydrazine Propellant

t = 0.002m

L = 0.33m

Lt = 0.5m

Mass = 1.8kg

Nitrogen Pressurant

t = 0.0071m

L = 0.09m

Lt = 0.3m

Mass = 1.7kg

Nitrogen Propellant

t = 0.013m

L = 1.6m

Lt = 2m

Mass = 98kg

LtL

t* 2 tanks of each per SCOUT

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Pressure Lines and Tank Attachments• Pressure lines

– A similar analyses as the tankage MER analysis has been conducted with a factor ofsafety of 4

• Diaphragms with thickness t = 0.002m

• Tank Structural Attachments– Pads and Rods/Hooks– Estimated 2% of the supported weight

• Support for Nitrogen Propellant = 3.78kg• Support for Hydrazine Propellant = 0.10kg• Support for Nitrogen Pressurant = 0.63kg

52015Length of the Lines (estimated) (m)

275Mass of the Lines (kg)

0.0050.0050.005Inner Radius (m)

272.22.7Max. Operating Pressure (Mpa)

Nitrogen HighPressure Lines

Hydrazine LowPressure Lines

Nitrogen LowPressure Lines

Pads

Rods

= 0.234kgMd=ρVdVd=(4/3)π[ri3-(ri-0.002)3]

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Tank and Thruster Placement• 16, 1N Nitrogen thrusters

– For contamination-critical sites

– 4 quads

• 16, 6N Hydrazine thrusters– For non-sensitive sites

– 4 triads

– 4 singles

NitrogenPressurant Tank

* One on each side

Hydrazine Propellant Tank

* One on each side

NitrogenPropellant Tanks

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Catalyst Bed Heaters

Valve Heaters Line Heaters

(T16)

(T14)

(T15)

(T13)

(T8)

(T6)

(T7)

(T5)

(T4)

(T2)

(T3)

(T1)

(T12)

(T10)

(T11)

(T9)

Bottom Left Panel

Bottom Right Panel

TopLeft Panel

TopRight Panel

Fill and Drain ValveFlow Control Valve Normally ClosedFlow Control Valve Normally OpenFilterThrust Chamber Valve (TCV)Valve Branch AValve Branch BHeaterPressureTemperatureThrusterIsolation Valve

(P)(T)

GN2GN2

(P)

(T) (T)

(P)

1A 4A

3A6A

6B

4B1B

3B

25

N2H4 N2H4

(P)

(T)

(T)

(P)

Hydrazine System Schematic

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SCOUT Power System CapabilitiesPower system requirements summary:

Li-Ion nominal operation mode (3 battery systems):

Nominal Sortie

11 hoursMax Charge Time Allowed29A @ 100V DCMaximum Discharge Rate Required9A @ 100V DCNominal Discharge Rate Required

2900WPeak Power Required

--293KLi-Ion Nom Operating Temperature (+/- 10 K)2.2 hrs4.4 hrs6.5 hrsSystem Reserve Endurance (9 A @ 100V DC)

--8.3 hrsLi-Ion Nom Charge Time65A130A195ALi-Ion Max Pulse Discharge Rate (@ 100V DC)5A10A15ALi-Ion Nom Discharge Rate (@100V DC)

6.5kW13.0kW19.5kWLi-Ion Peak Power Available2 Fail1 FailNo Fail

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Solid StateRecorderSolid StateRecorderLi-Ion Battery

Power Distribution Block Diagram

Firewire Data BusFirewire Data Bus

Legend:FDCC - Flight & Data Control Computer - Primary Avionics Components - Critical Crew Survival Systems - Mission Systems - Data Transfer - Power Transfer

Power DistributionUnit A

Docking ModulePower Resupply

Power DistributionUnit B

Power DistributionUnit C

Robotic Control

Low PowerComponents

FDCCFDCCFDCC

CompactPCI Bus

Standard PowerSystems (28 VDC)

• PDU:– Modulated for easy reconfiguration to meet

specific requirements– Capable of providing 97% efficiency at 1500W– Space qualified on several spacecraft

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Avionics Top-Level Block Diagram

Robotic Control

Communication/Video System

Propulsion System

Attitude Sensors

Astronaut Interface

Life Support Sensors

Firewire Data BusFirewire Data Bus

FDCCFDCCFDCC

CompactPCI Bus

Thermal Control

Power Distribution

ComputerDisplay

ComputerDisplay

Solid StateRecorder

Solid StateRecorder

Legend:FDCC - Flight & Data Control Computer - Primary Avionics Components - Critical Crew Survival Systems - Flight Control Systems - Mission Systems

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Communication Block DiagramUHFOmni

GimbaledKa-Band

Transponder

SensorData

Video System

Crew Interface - Hand Controllers - Switches - Voice

Flightcomputers

PowerAmplifierFDCC

FDCCFDCC

Video Displays AntennaSwitch

Diplexer

AntennaSwitch

Diplexer

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Processor Selection• Several radiation hardened processors were compared on the basis of

power consumption and performance• RAD750 is the most capable radiation hardened processor anticipated

to be in use during the SCOUT mission timeline– MTBF >390K hours = Reliability of >99.9% over 6 month mission

• SCOUT nominal operation distributes load between two FDCCs– Third FDCC for backup– Each FDCC is capable of individually supporting SCOUT tasks

BAE Systems

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Data Bus: IEEE 1394• SCOUT Baseline Design: IEEE 1394 (Firewire)

– Firewire exceeds the SCOUT requirement of 10Mbps data transfer (Maxtransfer of 500Mbps)

– Lower power requirements than Ethernet– Predicted to be the standard bus to transfer large amounts of rapidly

between peripherals and computers– Lowers cost of ground support equipment– Hot-swappable– Firewire has the added ability to transmit power in addition to data

• Redundant Linear Bus Topology– System reliability is above 99% given data bus reliability of at least 97%

Quatech

Power conductors (8 to 30V DC, 1.5A)6-pin connector only

External cable shielding

Two independently shielded twisted wire pairs fortransmit and receive connections(4-pin and 6-pin)

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Video Guidance Sensor• Video Guidance Sensor (VGS) used

for autonomous docking• Two active sensors located on

SCOUT• Passive targets mounted on each

IBDM on the docking module• Computer controlled maneuvers

allow for better accuracies, moreefficient maneuvering and a “softer”dock

• Originally developed as part ofNASA’s Automated Rendezvousand Capture (AR&C) system atMarshall Space Flight Center

• VGS provides all relative positionand attitude measurements (6-DOF)to the Guidance, Navigation, andControl (GN&C) system

Retro-Reflector Clusters

Active SensorPassive Target

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Video Cameras• Digital video cameras are to be placed on SCOUT to serve as an aid

to the astronaut• Estimated Camera Specifications

– Sensor: Complementary Metal Oxide Semiconductor (CMOS) Active PixelSensors (APS)

• Higher Frame Rates than CCD (Charge Couple Devices)• Smaller Dimensions• Lower Mass• Lower Power Consumption• More tolerant to radiation

– Dimensions: 90 x 55 x 80mm– Lens Aperture: 40mm diameter– Total Mass (including gimbals): 5.5kg– Total Peak Power (including gimbals): 15W

• Three cameras to be used on SCOUT– Two external

• Front• Rear

– One internal

Front Camera

Rear Camera

Internal Camera

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Costing• Cost based on heuristic formulas at the vehicle level for both

SCOUTs, the docking module, and the XMP• SCOUTs

– Non-recurring Cost ($M) = $1180 Million– 1st Unit Production = $87 Million– 2nd Unit Production = $70 Million

• Docking Module– Non-recurring Cost ($M) = $260 Million– 1st Unit Production = $71 Million

• XMP– Non-recurring Cost ($M) = $142 Million– 1st Unit Production = $35 Million

Total = $1850 Million

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Discussion of External Work Stations

Extravehicular MobilityUnit (EMU) and

Manned ManeuveringUnit (MMU)

Robonaut SCOUT

ILC Dover NASA Johnson Space Center

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System ComparisonSCOUTRobonautEMU w/MMU

N/A

N/A

N/A

Yes

Yes

Yes

Yes

Yes

No

25m

8hr

No

7hr + 0.5hrreserve

3g/cm2

No

No

No

No

No

Yes

120m

7hr

SHEEP/SAFER

11hr + 2hrreserve

4g/cm2

Yes

Yes

Yes

Yes

Yes

Yes

1000m

11hr

Bailout Systems

Life Support

Radiation Protection

2-Hand Operation

Single Person Op Capability

Autonomous Control

Human/Robotics Interaction

Teleoperation Control

On Site Human Intel

Max Sortie Distance

Max Sortie Duration

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SCOUT• SCOUT has a major advantage over both

EMU and Robonaut working togetherbecause:– Longer sortie duration and distance– No extra exertion for the astronaut– No need for pre-breathing– Room for astronaut to move in vehicle– Potential for long term excursions– Provides extra protection from deep space

environment• Radiation• Micrometeoroids• Thermal conditions

– Allows for use of robotic arms and humanarms together in a complementary manner

– Ability to maintain and repair GatewayStation and rest of SCOUT system

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Solution• SCOUT can handle the improvements necessary for

the space station emergency scenario– It is a single occupant vehicle– Needs minimal preparation time– Travels much faster than the RMS arm– Has the capabilities of three astronauts

• RMS operator = Grapple arm• Free-Floater = Task arms• RMS attached = AX-5 arms

– Allows for maximum work time due to• Low fatigue factor• Consumable availability

– Capabilities for day after day space construction

Revolutionary Solution = SCOUT

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The SCOUT Team• Avionics

– Aaron Hoskins– Will Miller– Oliver Sadorra– Greg Stamp

• Life Support and Human Factors– Katy Catlin– Avi Edery– John Hintz– Andrew Long– Alexandra Langley

• Loads, Structures, andMechanisms– Justin Richeson– Eric Rodriguez– Ernest Silva– Yudai Yoshimura

• Mission Planning and Analysis– Chris Bowen– Wendy Frank– Kirstin Hollingsworth– Sadie Michael– Jackie Reilly

• Power, Propulsion, and Thermal– Cagatay Aymergen– Matt Beres– Nathan Moulton– Christopher Work

• Systems Integration– Meghan Baker– Tom Christy– Jesse Colville– Robyn Jones– Lynn Pierson

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Outreach• March 6, 2003 – Preliminary Design Review• April 26, 2003 – Maryland Day• May 3, 2003 – Critical Design Review• May 12, 2003 – Aerospace Engineering

Department Briefing• May 13-14, 2003 – Aerospace Technology

Working Group conference

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Acknowledgements• Dr. Akin and Dr. Bowden for being our advisors for

this project• Brian Roberts for being one of our primary resources

throughout this design process• All of the people who came to give us feedback at

our Preliminary and Critical Design Reviews onMarch 6th and May 3rd

• Dr. Fourney and the Aerospace EngineeringDepartment at the University of Maryland for theirsupport

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