This is the Web Edition of "A Trip Into Space", a Coimbra-based electronic book on space science. Both the texts and the photos are by courtesy of National Aeronautics and Space Administration.

Asteroid Ida
Surface View

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 2480 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 wellknown prior to 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 fulldisk 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 fulldisk mosaic will permit detailed refinement of Ida's shape in this region. This highresolution 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.

The Galileo project, whose primary mission is the exploration of the Jupiter system in 1995-97, is managed for NASA's Office of Space Science by the Jet Propulsion Laboratory.


Last Update: 2005-Nov-29