Galileo completes week eleven of a 14-week-long survey of the Jovian magnetosphere

The second week of the new millennium finds Galileo completing week 11 of a 14-week-long survey of the Jovian magnetosphere. Playback of data stored during the spaceraft's December, 2000 passage through the Jupiter system is not scheduled to start until early next month. One engineering activity is performed by Galileo this week. On Monday, the spacecraft performs standard maintenance on its propulsion systems.

The survey of the Jovian magnetosphere is being performed by Galileo's Fields and Particles instruments. The Fields and Particles instruments are comprised of the Dust Detector, Energetic Particle Detector, Heavy Ion Counter, Magnetometer, Plasma Detector, and Plasma Wave instrument. The survey was initiated in late October, 2000 in conjunction with instruments on the Cassini spacecraft. Cassini flew past Jupiter on December 30. Although Cassini was generally expected to remain outside the magnetosphere until after the flyby, measurements indicate that it entered the bow shock region on December 27. In combination with Galileo measurements, this event may provide new information on the behavior of the magnetosphere. Galileo, on the other hand, has flown from the solar wind, into the Jovian magnetosphere, and is now flying back out into the solar wind. These joint studies with the Cassini spacecraft will yield information on the interaction between the solar wind and Jupiter's magnetosphere.

Galileo's survey data are recorded by its onboard tape recorder six times this week. Typically, these data are almost immediately packaged and transmitted to Earth. However, radio antennas of the Deep Space Network (DSN) are scheduled to listen to Galileo for only about 106 hours this week (out of a total 168 hours possible). In its place, the spacecraft makes use of a data buffer (a section of computer memory) to store up to seven hours of survey data at one time. When the buffer is full, and the DSN is not listening, the data are recorded by the tape recorder to prevent data loss.