The Galileo spacecraft, on its way to encounter Jupiter in 1995, has
flown by two small, main belt asteroids in the past three years.
The flyby of 951 Gaspra, on October 29, 1991, was the first
spacecraft visit to an asteroid. Galileo imaged the asteroid at
visual wavelengths from long range to its highest spatial
resolution of 50m and acquired spectral images from 0.7-5.2
. Solar wind and dust measurements were also obtained and
surprising perturbations at the magnetic
flux detectors were recorded at both asteroids [
Kivelson et al. 1993; Chapman, 1994].
Interpretation of the imaging data from the Solid-State Imager
(SSI) camera has provided knowledge of the asteroids' shape,
orientation in space, sense of rotation, surface morphology,
cratering history, photometric properties and color. A moon in
orbit around Ida was discovered (Figure 4)! With
the acquisition of these data, the asteroids have entered the realm
of geological study.