From: baalke@zagami.jpl.nasa.gov   
      
   Donald Savage   
   Headquarters, Washington                  September 17, 2003   
   (Phone: 202/358-1547)   
      
   Carolina Martinez   
   Jet Propulsion Laboratory, Pasadena, Calif.   
   (Phone: 818/354-9382)   
      
   RELEASE: 03-297   
      
   GALILEO TO TASTE JUPITER BEFORE TAKING FINAL PLUNGE   
      
        In the end, the Galileo spacecraft will get a taste of   
   Jupiter before taking a final plunge into the planet's   
   crushing atmosphere, ending the mission on Sunday, Sept. 21.   
   The team expects the spacecraft to transmit a few hours of   
   science data in real time leading up to impact.   
      
   The spacecraft has been purposely put on a collision course   
   with Jupiter to eliminate any chance of an unwanted impact   
   between the spacecraft and Jupiter's moon Europa, which   
   Galileo discovered is likely to have a subsurface ocean. The   
   long-planned impact is necessary now that the onboard   
   propellant is nearly depleted.   
      
   Without propellant, the spacecraft would not be able to point   
   its antenna toward Earth or adjust its trajectory, so   
   controlling the spacecraft would no longer be possible.   
      
   "It has been a fabulous mission for planetary science, and it   
   is hard to see it come to an end," said Dr. Claudia   
   Alexander, Galileo project manager at NASA's Jet Propulsion   
   Laboratory, Pasadena, Calif. "After traversing almost 3   
   billion miles and being our watchful eyes and ears around   
   Jupiter, we're keeping our fingers crossed that, even in its   
   final hour, Galileo will still give us new information about   
   Jupiter's environment."   
      
   Although scientists are hopeful to get every bit of data back   
   for analysis, the likelihood of getting anything is unknown   
   because the spacecraft has already endured more than four   
   times the cumulative dose of harmful jovian radiation it was   
   designed to withstand. The spacecraft will enter an   
   especially high-radiation region again as it approaches   
   Jupiter.   
      
   Launched in the cargo bay of Space Shuttle Atlantis in 1989,   
   the mission has produced a string of discoveries while   
   circling the solar system's largest planet, Jupiter, 34   
   times. Galileo was the first mission to measure Jupiter's   
   atmosphere directly with a descent probe and the first to   
   conduct long-term observations of the jovian system from   
   orbit.   
      
   It found evidence of subsurface liquid layers of salt water   
   on Europa, Ganymede and Callisto and it examined a diversity   
   of volcanic activity on Io. Galileo is the first spacecraft   
   to fly by an asteroid and the first to discover a moon of an   
   asteroid.   
      
   The prime mission ended six years ago, after two years of   
   orbiting Jupiter. NASA extended the mission three times to   
   continue taking advantage of Galileo's unique capabilities   
   for accomplishing valuable science. The mission was possible   
   because it drew its power from two long-lasting radioisotope   
   thermoelectric generators provided by the Department of   
   Energy.   
      
   >From launch to impact, the spacecraft has traveled   
   4,631,778,000 kilometers (about 2.8 billion miles).   
      
   Its entry point into the giant planet's atmosphere is about   
   1/4 degree south of Jupiter's equator. If there were   
   observers floating along at the cloud tops, they would see   
   Galileo streaming in from a point about 22 degrees above the   
   local horizon. Streaming in could also be described as   
   screaming in, as the speed of the craft relative to those   
   observers would be 48.2 kilometers per second (nearly 108,000   
   miles per hour). That is the equivalent of traveling from Los   
   Angeles to New York City in 82 seconds. In comparison, the   
   Galileo atmospheric probe, aerodynamically designed to slow   
   down when entering, and parachute gently through the clouds,   
   first reached the atmosphere at a slightly more modest 47.6   
   kilometers per second (106,500 miles per hour).   
      
   "This is a very exciting time for us as we draw to a close on   
   this historic mission and look back at its science   
   discoveries. Galileo taught us so much about Jupiter but   
   there is still much to be learned, and for that we look with   
   promise to future missions," said Dr. Charles Elachi,   
   director of JPL.   
      
   JPL, a division of the California Institute of Technology in   
   Pasadena, manages the Galileo mission for NASA's Office of   
   Space Science, Washington.   
      
   Additional information about the Galileo mission and its   
   discoveries is available online at:   
   http://galileo.jpl.nasa.gov   
      
   For information about NASA TV on the Internet, visit:   
   http://www.nasa.gov/multimedia/nasatv/index.html   
      
   For information about NASA, visit:   
   http://www.nasa.gov   
      
   -end-   
      
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