Galileo to fire thrusters to tweak course
Posted: March 13, 2001

An artist's concept of NASA's Galileo spacecraft in orbit around Jupiter. Photo: NASA/JPL
This week's major scheduled activity is a propulsive maneuver on Friday. This burn of the spacecraft's primary steering jets will help to refine the trajectory leading up to the next planned flyby of the satellite Callisto in late May.

The bulk of the week is occupied with playback of the data stored on the on-board tape recorder from the December flyby of Ganymede. The Near Infrared Mapping Spectrometer (NIMS) will complete the playback of its global map of Jupiter. This was a series of six observations which covered all 360 degrees of longitude and spanned from pole to pole on the giant planet. These observations provide information on the composition of Jupiter's clouds, and when combined with data from previous orbits, also show how the composition of the cloud layers can evolve with time.

The Solid State Imaging camera (SSI) will return a Jupiter Feature Track observation, so called because one atmospheric feature is tracked for a long period of time to see how it changes. This observation consists of a series of images of the turbulent region to the northwest of the Great Red Spot. This region is especially active and interesting, and has been the site of thunderstorm activity in the past. The area was imaged on four successive rotations of the planet (over the course of about 32 hours), to observe storm evolution over longer time scales than previously seen by Galileo. The observation used several infrared filters, which will allow scientists to view clouds at different depths in the atmosphere. These observations will have four times better resolution than those taken by the Cassini spacecraft, which was observing at the same time. The Cassini measurements will provide a global context for the more detailed Galileo pictures.