NEAR-Shoemaker Mission to 433 Eros

1. NEAR-Shoemaker Missionto 433 Eros 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 Cospar Capacity Building Workshop On Planetary Science Dr. Lucy McFadden July 30, 2007

3. Scientific Objectives • Determine physical and chemical properties of 433 Eros • Address major questions: • formation of the Solar System

4. Eros’ Orbital Properties • Mars-crossing • i=10.8° • Orbital period= 1.76 y • Rotation period=5.27hr

5. Journey to ErosBei dem Waldgott

6. Launched Feb. 17, 1996 • Delta 7925 launch vehicle • Cape Canaveral

7. Spacecraft • Fixed solar panels • 1.5 m high-gain antenna • 6 instruments

9. 253 Mathilde • June 27,1997 • 1212 km flyby • C-type asteroid • 66 x 48 x 44 km • Albedo = 0.047 • r=1.340± 200 kg/m3

10. Earth Swingby • Jan. 23, 1998 • 106.300 - 306.600 km • Trajectory maneuver • Match inclination • i=10° • Test and calibrate instruments

12. Psyche in der untwelt

13. 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

14. Psyche for Venus

15. Fundamental Properties • Mass=6.687 ± 1015 kg • Volume=2550 km3 • r=26 ±2 kg/m3 • Size=32x8x8 km • Rotation pole • RA 11.4°±.01 • Dec 17.3°±0.1

16. Eros : Major Questions • Is Eros a fragment or agglomerate? • Is Eros’ composition primitive or differentiated? • Does it have a magnetic field? • Are there satellites?

17. Shape

18. Near-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

19. Mineral Structure Orthopyroxene Clinopyroxene 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 The pyroxene group is composed of minerals of the general formula XYSi2O6, where X and Y are two divalent cations and occupy two Structurally 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.

21. Low Phase Flybyfor Spectroscopy

23. Spatially Resolved Spectroscopy • Variations in band depth and spectral slope • Range 1-4% • Includes phase angle corrections • Homogeneous to 4% • At 3 km resolution

24. Map of 1-µm Band Depth

28. Laser Rangefinder-lidar • Nd:YAG laser rangefinder • First detections from Eros at 290 km • Measures distance to surface along line of sight

29. Magnetometer • 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)

30. Global Rotation 2 Days after going into orbit around Eros

31. 200 km orbit

32. 100 Km orbit

33. Psyche Crater

34. Psyche is the same size as Barringer Crater Arizona, US

35. Low Altitude Flyover Oct. 26

36. 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

37. 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

42. End of Mission

43. http://near.jhuapl.edu

44. Tom Coughlin Andy Cheng Joe Veverka Jacob Trombka Bill Boynton Mario Acuna Maria Zuber Science Team Leaders

45. 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 Science Team Members