This Week on Galileo October 1-7, 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:
