Galileo Status Report - August 23, 1996
PUBLIC INFORMATION OFFICE JET PROPULSION LABORATORY CALIFORNIA INSTITUTE OF TECHNOLOGY NATIONAL AERONAUTICS AND SPACE ADMINISTRATION PASADENA, CALIF. 91109. TELEPHONE (818) 354-5011 http://www.jpl.nasa.gov
Plans are being finalized for Galileo's September 6 revisit of Jupiter's moon Ganymede, flying over its surface at only 262 kilometers (162 miles), the closest approach to any moon during the planned tour. Optical navigation images of Ganymede are being successfully received to ensure proper targeting for the flyby.
Meanwhile, the spacecraft continues to send back data from the observations its instruments made during the first flyby of Ganymede on June 27. Valuable data taken at that time included numerous observations of objects in addition to Ganymede, including Io, Europa, Callisto, and Jupiter itself. Galileo's Web page at http://www.jpl.nasa.gov/galileo is each day featuring a new image returned by the spacecraft. More than 100 images of objects in Jupiter's system have been returned by the spacecraft from this first encounter.
The Galileo team continues to develop plans to try to move a stuck filter wheel on the spacecraft's photopolarimeter radiometer. The instrument measures reflected and radiant energy emanating from Jupiter and its moons, yielding data on temperature and surface texture. After the last Ganymede flyby, engineers found that the filter wheel had stuck midway through the encounter. The filter wheel stuck at about the same time that the near-infrared mapper instrument experienced an unexplained anomaly, leading engineers to consider that Jupiter's intense radiation environment and its disruptive effects on Galileo's electronics may have contributed to the anomaly.
Following the Ganymede-2 flyby in early September, engineers plan to use heaters onboard the spacecraft to warm the photopolarimeter instrument in the hope that thermal expansion will help free the filter wheel. No observations will be made with the instrument until at least after the Ganymede-2 flyby, project officials said.
Today, Galileo is 676.1 million kilometers (420.1 million miles) from Earth and 7.2 million kilometers (4.4 million miles) from Ganymede. Its distance from Jupiter is about 6.9 million kilometers (4.2 million miles).