From: Jet Propulsion Laboratory
Posted: Monday, October 1, 2001
In addition to this week's playback, one engineering and one navigation activity dot the schedule. First, on Friday, routine maintenance of the spacecraft's propulsion system is performed.
Then, in preparation for the Io flyby coming up in two weeks, two optical navigation frames are shuttered. These two images frame the satellite Callisto and several stars. By comparing the relative positions of Callisto and the stars, ground navigators can help refine the position of the spacecraft, supplementing the usual radiometric tracking data used for orbit determination.
Over this past weekend, new software was loaded into the on-board computers that may help alleviate problems that the Solid State Imaging camera (SSI) has experienced in recent orbits. The aging electronics in the camera have proven susceptible to the high radiation environment near Jupiter. This has resulted in the loss of many of the images taken while Galileo is close to the planet. The target of Galileo's next two flybys is Io, the innermost of the four Galilean moons. During our last flyby (on August 5th), most of the images obtained in the vicinity of Io were affected by this problem. The new software patch is designed to reduce the amplitude of signals that are processed in the radiation-sensitive portions of the camera's circuitry and thus decrease the chance of a recurrence of the problem.
It is a true tribute to the designers of this workhorse spacecraft that, based on their work 20 years ago (before the first IBM PC hit the market!), today we have the ability to alter the workings of this robot from a distance of a half-billion miles!
As tape recorder playback from the early August flyby of Io nears an end, this week's data is expected from the Near Infrared Mapping Spectrometer (NIMS) and from the Photopolarimeter Radiometer (PPR).
From the NIMS instrument, data from observations of the Amirani, Prometheus, and Emakong regions on Io are expected, as well as from an area, not yet named, which recently showed evidence of significant new volcanic activity. Io is, after all, the most volcanically active body in the solar system!
The PPR instrument will be filling in some gaps in a global day-side temperature map of Io.
For more information on the Galileo spacecraft and its mission to Jupiter, please visit the Galileo home page at one of the following URL's:
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