Veverka et al., [1994] report the discovery of
linear depressions with a pitted appearance, called grooves
(Figure 5). On the highest resolution images (54 m/pixel)
obtained by the SSI, they cover 25
of the surface. The largest
ones are 400 m wide (though 90
of them are under 220 m) and
some extend 2.5 km in
length (or about 1/3 the asteroid's mean radius). The orientations
of the grooves follow two trends, one parallel to the 165-345
direction, the other falling along a family
of planes with orientation offset by 15
from the long axis of
the asteroid. These orientations are almost orthogonal to each
other and their preferred orientation is not an artifact of
illumination. The only other place in the solar system known to
have grooves is the Martian moon, Phobos. The most likely
explanation for their presence is that they represent fractures
modified by inward flow of regolith. Such fractures are evidence
of an energetic impact history.
The images obtained during Galileo's flyby of Gaspra indicate that
Gaspra formed from disruption of a larger precursor body and that
it has been subjected to more than one cratering episode in
its 
-yr lifetime. Its shape is controlled by a body-wide
structural fabric indicating that it is for the most part, a single
fragment of a larger precursor body.