Images from the SSI were used to derive a shape model of Gaspra
showing it to be a highly irregular object with principal diameters
of 
km and a mean radius of
km [ Thomas et al, 1994]. The mean
radius is in excellent agreement with ground-based
observations from which a radius of 6.2 km was derived
[ Tholen et al., 1994]. Its shape appears
to be derived from three long, flat surfaces and two large
concavities about 9-10 km across, features which have implications
for the internal structure of the asteroid and the effects of large
impacts. There is evidence that the body is one continuous
structure, a conclusion derived from observations of the straight
and continuous segments of grooves and the occurrence of preferred
directions. The grooves appear in both high and low areas, and
fall in one of two groups, a grouping that also holds in three
dimensions. Furthermore, the grooves and ridges correlate with the
flat areas [ Veverka et al., 1994].
Orientation in space and sense of rotation is determined by
Davies et al., [1994] based on a
control net of 19 points. The rotation sense is confirmed to be
prograde, and it is oriented in space with its north pole pointing
at 9.5
in azimuth and 26.7
in declination. These
results confirm the orientations determined from ground-based
telescopic light curves. This marks the
first ground-truth test of lightcurve measurements made over the
past three decades.