This Week On Galileo - July 6-12, 1998
Galileo spends all of this week processing and transmitting to Earth pictures and science information stored on its onboard tape recorder. The data was acquired during the spacecraft's close flyby of Jupiter's icy moon, Europa, in late May.
This week's playback schedule continues to access sections of the tape recorder from which data has already been retrieved once this orbit. A part of normal operations on Galileo, this second cut at the tape recorder provides the Project team the chance to fill all data gaps caused by transmission problems. It also allows the team to select entirely new data, or re-process data with different parameters.
This week's playback schedule includes three observations obtained by the camera, two observations by the near infrared mapping spectrometer and a portion of an observation recorded by the fields and particles instruments.
Two of the images returned by the camera capture an unusually rugged region of Europa. The region is east of the better known Tyre Macula impact crater and is characterized by pits, mounds and a very prominent ridge. The remaining image contains a previously unexplored region of Europa. The region's mottled or blotchy appearance is believed to indicate the presence of contaminants in the ice.
The near infrared mapping spectrometer observations focused on two different regions on Europa. The regions are located on Europa's leading side, which is shielded from impacts by particles carried by Jupiter's magnetosphere. You see, as the magnetosphere rotates with Jupiter, every 10 hours, it overcomes the satellite from behind, resulting in particle impacts with the trailing side. The absence of magnetospheric particles may reveal new information on the composition of the surface of Europa.
The fields and particles instruments return a portion of a high time resolution recording which measures dust, plasma, and electromagnetic fields near Europa. These data will expand the available knowledge of how Europa interacts with Jupiter's magnetosphere.
Finally, results from last week's gyroscope performance test are in. They indicate a minor improvement in the gyroscope performance. However, flight engineers believe that the improvement is too small to warrant any adjustments to the parameters in the attitude control computer's software. The software was modified in March to allow the computer to correctly interpret and use the anomalous gyroscope data. The gyroscope has been producing anomalous data since December 1997.