Galileo image of asteroid 951 Gaspra.
Gaspra Approach Sequence: 11 images taken by the Galileo spacecraft as it flew by the asteroid Gaspra.
Gaspra, Deimos, and Phobos Comparison.
Galileo image of asteroid 951 Gaspra.

Galileo image of asteroid 951 Gaspra.

Courtesy of NASA JPL

http://neo.jpl.nasa.gov/images/gaspra.html


This picture of asteroid 951 Gaspra is a mosaic of two images taken by the Galileo spacecraft from a range of 5,300 km (3,300 mi), some 10 minutes before closest approach 1991 October 29. The resolution, about 54 meters/pixel, is the highest for the Gaspra encounter. The portion illuminated in this view is about 18 km (11 mi) from lower left to upper right. The north pole is located at upper left; Gaspra rotates counterclockwise every 7 hours. The large concavity on the lower right limb is about 6 km (3.7 mi) across, the prominent crater on the terminator, center left, about 1.5 km (1 mi). A striking feature of Gaspra's surface is the abundance of small craters. More than 600 craters, 100-500 meters (330-1650 feet) in diameter are visible here. The number of such small craters compared to larger ones is much greater for Gaspra than for previously studied bodies of comparable size such as the satellites of Mars. Gaspra's very irregular shape suggests that the asteroid was derived from a larger body by nearly catastrophic collisions. Consistent with such a history is the prominence of groove-like linear features, believed to be related to fractures. These linear depressions, 100-300 meters wide and tens of meters deep, are in two crossing groups. Grooves had previously been seen only on Mars's moon Phobos, but were predicted for asteroids as well. The Galileo project, whose primary mission is the exploration of the Jupiter system in 1995-97, is managed by the Jet Propulsion Laboratory.