Tuesday, September 27, 2005

Remnants of a Lost Approach

When Galileo approached Jupiter in the 1990s, the antenna problem, as well as a tape recorder problem in fall of 1995 that cost the images from the arrival orbit pretty much wiped out the return of images from this part of the mission, other than the Ida encounter, from which the images were piddled back over many months. In 1990, before even the Gaspra encounter, Galileo took some images for calibration that could be returned more easily while it was still in the inner solar system. Here is a color view of Jupiter and some of its moons generated from this data. It has the appearance of being taken through a small telescope.

Galileo would next image Jupiter during the SL9 imacts, a year and a half before arrival. It used a technique known as an "on chip mosaic," taking multiple images on the same frame so it could be returned as one picture. There were several techniques used that involved smearing the image to look for flareups from the impact. For the last impact, Galileo took multiple unsmeared images, providing a neat perspective, as its images are the only ones to see the impacts directly, and not coming over the limb. Perhaps another entry will be dedicated to these images. But here is one showing the impact and Jupiter, produced from several images on the on-chip mosaic.

The tape recorder problem caused the end of imaging until the G1 orbit in the summer of 1996. However, as Galileo approached in 1995, it took optical navigation frames showing Ganymede slowly looming larger to help plan for the G1 orbit. It is a little taste of the sights Galileo saw that fall but could not show us.

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