This Week On Galileo
December 7-13, 1998
This week the Galileo flight team will send a new set of commands to the spacecraft to conduct real-time and recorded science. These new activities will take advantage of DSN antenna time which was originally intended for playback of science data from Galileo's most recent flyby of Europa on November 22. The majority of these data were not recorded on the spacecraft, because it suffered two anomalies and on-board software halted execution of the encounter commands. On Thursday, in addition to these new activities, the spacecraft performs regular maintenance on its propulsion systems.
Three observations will be recorded on the spacecraft's on-board tape recorder this week. In the first observation the spacecraft camera takes images of Saturn's moon Titan, Saturn, Uranus, and Neptune. The data retrieved from this observation will be used to calibrate some of the camera's filters. In the second, the near-infrared mapping spectrometer looks at the star Sirius. This data will also be used for instrument calibration.
Finally, the fields and particles instruments will collect recorded data for five hours as the spacecraft moves through the center of a region known as the plasma sheet. This region lies along Jupiter's magnetic equator, and is slightly offset from the planetary equator due to a small tilt in Jupiter's magnetic field. Plasma, which is composed of ionized gases that originate from Jupiter's moon Io, is strongly concentrated in this region, allowing relatively strong electric currents to flow. The plasma sheet crossing will occur in the duskward part of the magnetosphere, 109 Jupiter radii (7.8 million kilometers or 4.8 million miles) from the planet. In this largely unexplored region, Jupiter's magnetic field and the solar wind both influence the state of the plasma sheet.
After the observations are complete, the spacecraft will begin processing and transmission of the stored data. In addition, the fields and particles instruments continue their survey of Jupiter's magnetosphere in real-time, sharing DSN antenna time with the recorded data playback process.