near-shoemaker mission to 433 eros
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Cospar Capacity Building WorkshopOn
Planetary Science
N e a r E a r t h A s t e r o i d R e n d e z v o u s
Dr. Lucy McFadden
July 30, 2007
NEAR-Shoemaker Missionto 433 Eros
NEAR-Shoemaker Missionto 433 Eros
Scientific ObjectivesScientific Objectives
• Determine physical and chemical properties of 433 Eros
• Address major questions: – formation of the Solar
System
Eros’ Orbital PropertiesEros’ Orbital Properties
• Mars-crossing• i=10.8°• Orbital period= 1.76 y• Rotation period=5.27hr
Journey to ErosBei dem WaldgottJourney to Eros
Bei dem Waldgott
Launched Feb. 17, 1996Launched Feb. 17, 1996
• Delta 7925 launch vehicle
• Cape Canaveral
QuickTime™ and aVideo decompressor
are needed to see this picture.
SpacecraftSpacecraft
• Fixed solar panels• 1.5 m high-gain
antenna• 6 instruments
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are needed to see this picture.
253 Mathilde253 Mathilde
• June 27,1997• 1212 km flyby • C-type asteroid• 66 x 48 x 44 km• Albedo = 0.047• =1.340± 200 kg/m3
Earth SwingbyEarth Swingby
• Jan. 23, 1998• 106.300 - 306.600 km• Trajectory maneuver
– Match inclination
– i=10
• Test and calibrate instruments
Psyche in der untweltPsyche in der untwelt
Engine burn abort/Eros flyby
Engine burn abort/Eros flyby
• December 20, 1998– Aborted maneuver
– +27 hrs regained contact
• December 23, 1998– 3827 km flyby
• January 3, 1999– Bipropellant burn
– Feb. 2000 rendezvous
Psyche for VenusPsyche for Venus
Fundamental PropertiesFundamental Properties
• Mass=6.687 ± 1015 kg• Volume=2550 km3
• kg/m3
• Size=32x8x8 km• Rotation pole
– RA 11.4°– Dec 17.3°±0.1
Eros : Major QuestionsEros : Major Questions
• Is Eros a fragment or agglomerate?
• Is Eros’ composition primitive or differentiated?
• Does it have a magnetic field?
• Are there satellites?
ShapeShape
Near-IR SpectroscopyNear-IR Spectroscopy
• Low phase flyby 0-50°• >5600 spectra • 800-2500 nm• 12 -2.5 km/spectrum
– 0.76 x 0.38° slit
• 1st spatially resolved spectra
Mineral Structure
The pyroxene group is composed of minerals of the general formula XYSi2O6, where X and Y are two divalent cations and occupy twoStructurally different sites. If X and Y are the same small-radius divalent cation like Fe or Mg the resultant structure is commonly orthorhombic, giving us the orthopyroxene group.
Orthopyroxene
Olivine
The olivine group is composed of minerals of the general formula X2SiO4 where X = Mg ,Fe2+, or Ca; Y = Al, Cr, or Fe3+; and Z = Si. The X-site is 8 coordinated, the Y -site is 6-coordinated (octahedral) and the Z-site is 4-coordianted
Clinopyroxene
Low Phase Flybyfor SpectroscopyLow Phase Flybyfor Spectroscopy
Spatially Resolved Spectroscopy
Spatially Resolved Spectroscopy
• Variations in band depth and spectral slope– Range 1-4%
– Includes phase angle corrections
– Homogeneous to 4%
– At 3 km resolution
Map of 1-µm Band DepthMap of 1-µm Band Depth
Laser Rangefinder-lidarLaser Rangefinder-lidar
• Nd:YAG laser rangefinder
• First detections from Eros at 290 km
• Measures distance to surface along line of sight
MagnetometerMagnetometer
• Three-axis fluxgate magnetometer
• No magnetic field detected
• Sensitivity of 1 nT
• Upper limit at 200 km orbit is B=30,000 nt (earth-like)
Global Rotation 2 Days after
going into orbit around Eros
Global Rotation 2 Days after
going into orbit around Eros
200 km orbit200 km orbit
100 Km orbit100 Km orbit
Psyche CraterPsyche Crater
Psyche is the same size as Barringer Crater Arizona,
US
Psyche is the same size as Barringer Crater Arizona,
US
Low Altitude Flyover Oct. 26
Low Altitude Flyover Oct. 26
X-ray Gamma-Ray Spectrometer
X-ray Gamma-Ray Spectrometer
• First detections – class X solar flare
• Mg, Fe, Ca– Verified calibrations
• Interplanetary Gamma Ray Burst Network– Earth orbiting satellites
and Ulysses s/c– Location of optical and
radio counterparts
X-ray and -ray spectroscopy
• Data acquired during 5 solar flares and during two extended “quiet Sun” periods.
• Large systematic uncertainties, but relative ratios are reliable.
• Primitive, undifferentiated ratios of– Mg/Si, Al/Si, Ca/Si and Fe/Si
• global differentiation is ruled out.• S/Si is below chondritic values• Nittler et al. 2001 MAPS, 36, 1673-1695
End of MissionEnd of Mission
http://near.jhuapl.eduhttp://near.jhuapl.edu
Science Team LeadersScience Team Leaders
• Tom Coughlin• Andy Cheng• Joe Veverka
• Jacob Trombka• Bill Boynton• Mario Acuna• Maria Zuber
Science Team MembersScience Team Members
• J.P. Barriot• James F. Bell• Mark Robinson• Scott Murchie• Michael Malin• Clark Chapman• Lucy McFadden
• William Boynton• Christopher Russell• Alexander Konopliv• Steven Squyres• Peter C. Thomas• Johannes Brueckner
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