This Week on Galileo - March 9-15, 1998
After ending an uneventful period of limited communications, Galileo resumes the processing and transmission of pictures and science information stored on the spacecraft's onboard tape recorder. The data was acquired and stored on the tape recorder during the spacecraft's close flyby of Jupiter's moon Europa in Dec. 1997. The 2-1/2 week period of limited communications was caused by solar conjunction, a period of time during which the sun passes between the Earth and the spacecraft and solar activity causes radio signals to and from the spacecraft to become noisy or garbled.
The data scheduled for processing and transmission to Earth this week includes primarily information from the spacecraft's Near Infrared Mapping Spectrometer's (NIMS) observation of the Pwyll impact crater region on Europa. The NIMS information will allow scientists to learn more about the different types of materials found in this region. To see what this region looks like you can look for images taken by the spacecraft's camera that were recently released on our home page. Other information scheduled for transmission toward the end of this week includes data from the spacecraft's suite of fields and particles instruments that will add to the repository of information characterizing the interaction of Europa with the magnetic and electric fields surrounding Jupiter. Finally, the camera team has scheduled the processing and transmission of a picture of the Conamara Chaos region and another picture of a region of mottled terrain.
If some of these information sets sound familiar, it is because they are part of Galileo's normal period of re-processing and re-transmission of observations that have previously been transmitted to Earth. This second "pass" through the recorded data allows the science teams to fill up gaps in information caused by transmission problems the first time around. The second pass also provides the opportunity to replay portions of observations that have been identified as particularly interesting or to simply add additional data from a particular observation.
Also scheduled this week is a test of the spacecraft's attitude control system. This test will provide engineers with information to help them determine whether the attitude control system's anomalous behavior has stabilized or is getting worse. Remember that the spacecraft performed a close flyby of Europa just prior to the start of our period of limited communications. During this flyby, the spacecraft was once again exposed to Jupiter's intense radiation environment. Radiation is considered a leading candidate as a cause of the hardware fault in one of the attitude control system's gyroscopes, and which has led to the anomalous behavior. Limited information contained in the spacecraft's normal engineering data set suggests that the anomalous gyroscope behavior has not deteriorated.
At the end of this week, the spacecraft is scheduled to perform the next flight path correction. This correction will fine tune the spacecraft's orbit as it heads back toward the Jupiter system and another close encounter with Europa.