Galileo Mission Status - January 30, 1998
MEDIA RELATIONS OFFICE JET PROPULSION LABORATORY CALIFORNIA INSTITUTE OF TECHNOLOGY NATIONAL AERONAUTICS AND SPACE ADMINISTRATION PASADENA, CALIF. 91109. TELEPHONE (818) 354-5011 http://www.jpl.nasa.gov
NASA's Galileo spacecraft has been transmitting to Earth this past week pictures and other science information gathered during the Dec. 16, 1997 flyby of Jupiter's icy moon, Europa. The information, which had been stored on the spacecraft's onboard tape recorder, includes fields and particles observations of the interaction between Europa and Jupiter's magnetic and electric field environment. Also included are pictures and observations of Europa's wedged regions and hot regions. Important observations of surface changes on the volcanic moon Io will help later on in the Galileo Europa Mission, when one or two close Io flybys are planned.
Next week, Galileo will transmit science information and pictures of Europa's regions of fretted shapes and regions of dark lines, as well as images of the Gilgamesh region on another Jovian moon, Ganymede.
There have been no further occurrences of anomalous behavior by Galileo's attitude control subsystem, which controls where the spacecraft and scan platform are pointing. Team members have confirmed that a hardware error in one of the spacecraft's two gyroscopes caused the two anomalies, which temporarily slowed down the rate at which data could be transmitted to Earth. The gyroscopes are used to point the spacecraft when very precise pointing control and knowledge of the spacecraft's position and orientation are needed, usually for camera and other remote sensing science observations or for maneuvers that adjust the spacecraft's flight path. The team will continue studying the anomalies to determine whether they may recur and to design ways to work around the situation for the remainder of the mission.
A flight path maneuver was performed successfully on Thursday, Jan. 22, to prepare for Galileo's upcoming Europa encounter on Feb. 10. Special precautions were taken in the design of this maneuver to minimize its vulnerability to any gyro problems. Another flight path maneuver will be performed on Sat., Feb. 7, if it is deemed necessary for fine-tuning before Galileo's Europa flyby on Feb. 10. Because of the solar conjunction, when the Sun is between Galileo and Earth, that flyby will include no data collection except for radio science information.
On Tues. Feb. 3, the spacecraft will be turned slightly to adjust the antenna position. The turn will be executed in normal mode with some precautions built in, but no problem is anticipated. This will be the final attitude adjustment needed before the end of February, when Galileo leaves its solar conjunction period.
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