The Galileo imaging system captured this picture of the limb of the asteroid 243 Ida about 46 seconds after its closest approach on August 28, 1993, from a range of only 2,480 kilometers. It is the highest-resolution image of an asteroid's surface ever captured, and shows detail at a scale of about 25 meters per pixel.
This image is one frame of a mosaic of 15 frames shuttered near Galileo's closest approach to Ida. Since the exact location of Ida in space was not well-known before the Galileo flyby, this mosaic was estimated to have only about a 50 percent chance of capturing Ida. Fortunately, this single frame did successfully image a part of the sunlit side of Ida.
The area seen in this frame shows some of the same territory seen in a slightly lower resolution full-disc mosaic of Ida returned from the spacecraft in September, 1993, but from a different perspective. Prominent in this view is a 2-kilometer-deep "valley" seen in profile on the limb. This limb profile and the stereoscopic effect between this image and the full-disc mosaic will permit detailed refinement of Ida's shape in this region. This high-resolution view shows many small craters and some grooves on the surface of Ida, which give clues to understanding the history of this heavily impacted object.
P-44130 May 25, 1994