Galileo Europa Mission Status
November 23, 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
Galileo project engineers expect the spacecraft to return to normal operations today at about 5 p.m. Pacific Standard Time, following a weekend in which the spacecraft entered safing mode twice. The first of these events prevented Galileo from gathering data on Europa as it flew by the icy moon early Sunday, November 22.
Galileo engineers believe the safing events, which act as a built-in protection system, were triggered by resets of the portion of the craft's control and data subsystems that control the non-spinning part of the spacecraft. These subsystems handle Galileo's communications and transmission of data to Earth.
Galileo's health and safety are not in jeopardy. The anomalies occurred Saturday, November. 21, at 9:34 pm PST, and Sunday, November 22, at 5:30 p.m. The first safing happened about six hours before Galileo was scheduled to fly by Europa, and two hours before its closest approach to Jupiter's intense radiation.
Before entering safing mode, Galileo performed ultraviolet spectrometer observations, and its near infrared mapping spectrometer performed an observation of Jupiter's white oval storm system. It also obtained some radio science measurements of Europa even while in safing mode. However, the craft was unable to gather data on Europa or Io.
These anomalies are somewhat similar to a reset that occurred during a previous Europa flyby last June. However, in the latest anomalies, the semi-redundant halves of the control and data subsystems reset simultaneously, while in June they reset one after the other.
The Galileo team has been sending commands to the spacecraft to restore its operations. In fact, the Sunday night safing occurred just before the craft recovered from the Saturday safing. Once Galileo is functioning normally again, the project team will develop a plan to have the spacecraft transmit to Earth the data it gathered.
This weekend's Europa flyby was the 10th performed by the Galileo spacecraft; another Europa encounter is planned for January 31, 1999. The spacecraft has spent the past three years orbiting Jupiter and its moons, including Europa, and has provided scientists with a wealth of information and pictures. Its primary mission ended in December 1997, and the spacecraft is currently in the midst of a two-year extension, known as Galileo Europa Mission.
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