[Previous] | [Session 1] | [Next]
A. F. Cheng (Applied Phys Lab Johns Hopkins Univ), NEAR Team
The NEAR spacecraft has performed flybys of two asteroids, the C-type main belt asteroid 253 Mathilde and the S-type near-Earth asteroid 433 Eros. Mathilde has an unusually long rotation period of 17.4 days, so NEAR could view only one face during its 10 km/s flyby in June, 1997. NEAR returned 537 images and made the first direct measurement of the mass of a C asteroid. Mathilde's density is only 1.3 g/cc, indicating a porosity of at least 50%. Several giant craters up to 33 km wide formed on Mathilde, which is itself only 46x48x66 km in size. No color or albedo variations were detected. Next up for NEAR is the rendezvous with Eros, which was originally scheduled for January, 1999 but which will now take place in February, 2000. NEAR's rendezvous burn on December 20, 1998 aborted, and NEAR executed a flyby of Eros on December 23, 1998. NEAR returned 222 images from the Eros flyby and determined the density of Eros to be 2.5 g/cc - Eros is not as porous as Mathilde. Interestingly, Eros is not covered with giant craters, and it does display color variations over its surface.