Galileo Europa Mission Status Report
June 14, 1999
MEDIA RELATIONS OFFICE
JET PROPULSION LABORATORY
CALIFORNIA INSTITUTE OF TECHNOLOGY
NATIONAL AERONAUTICS AND SPACE ADMINISTRATION
PASADENA, CALIFORNIA 91109. TELEPHONE (818) 354-5011
http://www.jpl.nasa.gov
Contact: Jane Platt
Various scientific discoveries by NASA's Galileo spacecraft have been reported recently. In one discovery, a cloud of microscopic dust grains surrounding Jupiter's large moon Ganymede has been found by Galileo's Dust Detector System (DDS). Scientists believe this dust cloud is created when interplanetary meteoroids slam into Ganymede's surface. The findings are featured in last week's edition of the journal Nature.
Scientists are also poring over intriguing findings about surface temperatures on Jupiter's moon Europa gathered by Galileo's Photopolarimeter Radiometer, which measures temperature and other traits of Jupiter's atmosphere, clouds and moons. The information, published in the journal Science, reveals that while Europa's daytime temperatures are as expected, its nighttime temperatures are puzzling. At night, it appears the temperatures vary considerably from place to place, in patterns not related to geology or reflectivity of the surface.
Spacecraft engineers are trying to find out why one of the two channels on the photopolarimeter-radiometer showed little or no signal during the recent flyby of Jupiter's pockmarked moon, Callisto. The affected channel is used to measure temperatures of Jupiter and its moons.
Also in the most recent batch of data played back by Galileo is an observation of Europa, taken while the icy moon was in Jupiter's shadow. The observation was made by Galileo's Near-Infrared Mapping Spectrometer. There are also pictures of cratered terrain that will help scientists calculate the age of Callisto's surface, and other observations of the young Bran crater, which offers a good view of Callisto's crust.
The tape recorder playback will be paused twice this week. On Tuesday, it will pause for a standard gyroscope performance test and for a turn to keep the spacecraft antenna pointed toward Earth. On Saturday, standard maintenance on Galileo's propulsion system will be performed.
Galileo's next destination is another flyby of Callisto on June 29 at 11:47 p.m. Pacific Daylight Time. The spacecraft has been orbiting Jupiter and its moons for 3½ years. Right now, the spacecraft is more than halfway through a two-year extended Galileo Europa Mission, a follow-on to the primary mission that ended in December 1997. JPL manages the mission for NASA's Office of Space Science, Washington, D.C.
JPL is a division of the California Institute of Technolgy, Pasadena, CA.
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