This Week On Galileo - April 6-12, 1998
Galileo spends most of the week processing and transmitting to Earth pictures and other science information gathered during the spacecraft's recent encounter with the Jupiter system. The data returned to Earth this week includes information on Io, Europa and Jupiter's magnetic and electric field environment. On Friday of this week, the spacecraft performs regular maintenance on its propulsion system and then performs a turn to keep its radio antenna pointed toward the Earth.
This week's data processing schedule starts with an observation performed by the Near Infrared Mapping Spectrometer (NIMS). The observation contains science information describing the south pole of Jupiter's volcanic moon Io. The data is the highest resolution of Io that will be possible through Spring of 1999 and the best view of Io's south pole possible until the spacecraft's return to Io in late 1999.
The Photopolarimeter Radiometer team returns one of three observations performed by their instrument designed to refine maps of temperature variation across Europa's surface. These maps will be useful in understanding the different ages of Europa's surface, how the surface might have been formed and the different materials found on the surface. NIMS and the spacecraft's camera, or Solid State Imaging (SSI) subsystem, will return information on a region of dark lines and the Mannann'an crater, respectively. Together with other observations, the Mannann'an crater pictures are expected to result in stereo pictures of the region.
Finally, this week's playback and transmission of data recorded on the spacecraft includes information from the fields and particles instruments regarding the interaction of Jupiter's magnetic and electric field environment with Europa. This type of information is gathered during almost every orbit, with each orbit providing new scientific understanding of these phenomena.
Preliminary results from last week's attitude control system performance test have provided indications that the behavior of the system's gyroscopes did not degrade further during the latest passage through Jupiter's intense radiation environment last month. In addition, further investigation into the possible cause of the anomalous behavior has identified a single computer chip. Of many computer chips involved in the operation of the spacecraft's gyroscopes, this chip is slightly more exposed to the radiation environment. The malfunction of this chip seems to be consistent with the anomalous behavior observed with the attitude control system.