Imaging of asteroid 433 Eros during NEAR's flyby reconnaissance

Science

Volumn 285, Issue 5427, 1999, Pages 562-564

  Veverka, J ^a   Thomas, P C ^a   Bell III, J F ^a   Bell, M ^a   Carcich, B ^a   Clark, B ^a   Harch, A ^a   Joseph, J ^a   Martin, P ^a   Robinson, M ^b   Murchie, S ^c   Izenberg, N ^c   Hawkins, E ^c   Warren, J ^c   Farquhar, R ^c   Cheng, A ^c   Dunham, D ^c   Chapman, C ^d   Merline, W J ^d   McFadden, L ^e   Wellnitz, D ^e   Malin, M ^f   Owen Jr , W M ^g   Miller, J K ^g   Williams, B G ^g   Yeomans, D K ^g   more..

^a Department of Obstetrics Gynecology   (United States)

^b NORTHWESTERN UNIVERSITY   (United States)

^c APPLIED PHYSICS LABORATORY   (United States)

^d SOUTHWEST RESEARCH INSTITUTE   (United States)

^e Bldg 142   (United States)

^f MALIN SPACE SCIENCE SYSTEMS   (United States)

^g CALIFORNIA INSTITUTE OF TECHNOLOGY   (United States)

Author keywords

[No Author keywords available]

Indexed keywords

ASTEROID; IMAGE RESOLUTION;

ARTICLE; ASTRONOMY; GEOGRAPHY; IMAGE ANALYSIS; PRIORITY JOURNAL; SPACE FLIGHT;

ASTEROIDEA;

EID: 0033597798     PISSN: 00368075     EISSN: None     Source Type: Journal    
DOI: 10.1126/science.285.5427.562     Document Type: Article

References (30)

1. R. W. Farquhar et al., Astronaut. Sci. 43, 353 (1995).
2. D. K. Yeomans et al., Science 285, 560 (1999).
3. D. K. Veomans, J. Astronaut. Sci. 43, 417 (1995); S. J. Ostro et al., Icarus 84, 334 (1990); D. Mitchell et al., ibid. 131, 4 (1998); M. D. Hicks et al., ibid., in press.
4. D. K. Veomans, J. Astronaut. Sci. 43, 417 (1995); S. J. Ostro et al., Icarus 84, 334 (1990); D. Mitchell et al., ibid. 131, 4 (1998); M. D. Hicks et al., ibid., in press.
5. D. K. Veomans, J. Astronaut. Sci. 43, 417 (1995); S. J. Ostro et al., Icarus 84, 334 (1990); D. Mitchell et al., ibid. 131, 4 (1998); M. D. Hicks et al., ibid., in press.
6. D. K. Veomans, J. Astronaut. Sci. 43, 417 (1995); S. J. Ostro et al., Icarus 84, 334 (1990); D. Mitchell et al., ibid. 131, 4 (1998); M. D. Hicks et al., ibid., in press.
7. The sequence began with an inbound satellite search at 15:30 UTC when the spacecraft was 11,672 km from Eros and the solar phase angle was 84°. Near closest approach (3827 km), the goal was to obtain continuous coverage of Eros. Because of uncertainties in the asteroid's position relative to the spacecraft, a large area of the sky had to be imaged to ensure that views of Eros were obtained near closest approach. A sequence was designed that interlaced 2 × 2 mosaics (2 frames across and 2 down) with an additional single frame centered on the most probable position of Eros. Images were taken through seven filters at each position with automatic exposure (19). At closest approach, a single 4 × 4 clear-filter mosaic sequence was executed.
8. J. Warren et al., Space Sci. Rev. 82, 101 (1997).
9. During an attitude anomaly that occurred immediately after the aborted burn on 20 December and persisted for 27 hours, more than 28 kg of hydrazine was burned by attitude control jets, creating a diffuse cloud of hydrazine and burn products around the spacecraft. We believe that the enhanced scattering in the Eros flyby images resulted when these materials condensed on the cold outer optics of the imager. Observations of star fields are planned during the remainder of the cruise to Eros to monitor the tight-scattering and transmission properties of the camera.
10. Our estimate is based on P. D. Hamilton and J. A. Burns, Icarus 92, 118 (1991).
11. D. Mitchell et al., ibid. 131, 4 (1998).
12. B. Zellner, ibid. 28, 149 (1976).
13. J. Veverka et al., Science 278, 2109 (1997); D. K. Yeomans et al., ibid., p. 2106.
14. J. Veverka et al., Science 278, 2109 (1997); D. K. Yeomans et al., ibid., p. 2106.
15. S-type asteroids have moderate albedos and spectra, indicating silicates such as olivine or pyroxene. C-type asteroids have low albedos and spectra, indicating carbon or carbonaceous materials on their surfaces [for example, D. J. Tholen and M. A. Barucci, in Asteroids II, R. P. Binzel, T. Gehrels, M. S. Matthews, Eds. (Univ. of Arizona Press, Tucson, AZ, 1989), pp. 298-315].
16. M. J. S. Belton et al., Nature 374, 785 (1995).
17. H. Melosh and E. Ryan, Icarus 129, 562 (1997).
18. S. K. Croft, ibid. 99, 402 (1992).
19. For Caspra, see C. R. Chapman et al., ibid. 120, 231 (1996). For Ida, see C. R. Chapman et at., ibid., p. 77.
20. For Caspra, see C. R. Chapman et al., ibid. 120, 231 (1996). For Ida, see C. R. Chapman et at., ibid., p. 77.
21. On the surface of Caspra, Galileo observed structures of global dimensions (such as planar facets and linear grooves). We note that the specific predictions about the shape of Eros made recently by W. F. Bottke et al. (Astron. J., in press) are not supported by the NEAR images. That model considers Eros to be a rubble pile, the shape of which has been influenced by tidal forces during a presumed close passage to Earth.
22. J. Veverka et al., Icarus 107, 72 (1994).
23. For Dactyl, see C. R. Chapman et al., Nature 374, 783 (1995); M. Belton et al., Icarus 120, 1 (1996). For the discovery of Eugenia's moon, see W. J. Merline et al., Nature, in press.
24. For Dactyl, see C. R. Chapman et al., Nature 374, 783 (1995); M. Belton et al., Icarus 120, 1 (1996). For the discovery of Eugenia's moon, see W. J. Merline et al., Nature, in press.
25. For Dactyl, see C. R. Chapman et al., Nature 374, 783 (1995); M. Belton et al., Icarus 120, 1 (1996). For the discovery of Eugenia's moon, see W. J. Merline et al., Nature, in press.
26. The MSI camera covers the spectral range from 400 to 1100 nm. For filter specification and nomenclature, see J. Veverka et al., J. Geophys. Res. 102, 23709 (1997). The MSI automatic exposure algorithm is described by S. E. Hawkins et al. [Space Sci. Rev. 82, 31 (1997)].
27. The MSI camera covers the spectral range from 400 to 1100 nm. For filter specification and nomenclature, see J. Veverka et al., J. Geophys. Res. 102, 23709 (1997). The MSI automatic exposure algorithm is described by S. E. Hawkins et al. [Space Sci. Rev. 82, 31 (1997)].
28. 5. Murchie and C. Pieters, J. Geophys. Res. 101, 2201 (1996).
29. M. D. Hicks et al., Icarus, in press.
30. We thank the Mission Design, Mission Operations, and Spacecraft teams of the NEAR Project at the Applied Physics Laboratory of Johns Hopkins University for their dedicated and vigorous efforts that led to the successful return of key data from the 23 December 1998 flyby. We thank three anonymous reviewers for their comments and suggestions.