Historic First: A Spacecraft Orbits Mercury   
       
   March 18, 2011: NASA's MESSENGER spacecraft successfully achieved orbit around   
   Mercury at approximately 9 p.m. EDT on Thursday, March 17. This marks the   
   first time a spacecraft has accomplished this engineering and scientific   
   milestone at our solar system's innermost planet.   
       
   "This mission will continue to revolutionize our understanding of Mercury   
   during the coming year," said NASA Administrator Charles Bolden, who was at   
   MESSENGER mission control at the Johns Hopkins University Applied Physics   
   Laboratory in Laurel, Md., as engineers received telemetry data confirming   
   orbit insertion. "NASA science is rewriting text books. MESSENGER is a great   
   example of how our scientists are innovating to push the envelope of human   
   knowledge."   
   [...]   
   An artist's concept of MESSENGER orbiting Mercury. [more]   
       
   At 9:10 p.m. EDT, engineers Operations Center, received the anticipated   
   radiometric signals confirming nominal burn shutdown and successful insertion   
   of the MESSENGER probe into orbit around the planet Mercury. NASA's MErcury   
   Surface, Space ENvironment, Geochemistry, and Ranging, or MESSENGER, rotated   
   back to the Earth by 9:45 p.m. EDT, and started transmitting data. Upon review   
   of the data, the engineering and operations teams confirmed the burn executed   
   nominally with all subsystems reporting a clean burn and no logged errors.   
       
   MESSENGER's main thruster fired for approximately 15 minutes at 8:45 p.m.,   
   slowing the spacecraft by 1,929 miles per hour and easing it into the planned   
   orbit about Mercury. The rendezvous took place about 96 million miles from   
   Earth.   
       
   "Achieving Mercury orbit was by far the biggest milestone since MESSENGER was   
   launched more than six and a half years ago," said Peter Bedini, MESSENGER   
   project manager of the Applied Physics Laboratory (APL). "This accomplishment   
   is the fruit of a tremendous amount of labor on the part of the navigation,   
   guidance-and-control, and mission operations teams, who shepherded the   
   spacecraft through its 4.9-billion-mile journey."   
       
   For the next several weeks, APL engineers will be focused on ensuring the   
   spacecraft's systems are all working well in Mercury's harsh thermal   
   environment. Starting on March 23, the instruments will be turned on and   
   checked out, and on April 4 the mission's primary science phase will begin.   
       
   "Despite its proximity to Earth, the planet Mercury has for decades been   
   comparatively unexplored," said Sean Solomon, MESSENGER principal investigator   
   of the Carnegie Institution of Washington. "For the first time in history, a   
   scientific observatory is in orbit about our solar system's innermost planet.   
   Mercury's secrets, and the implications they hold for the formation and   
   evolution of Earth-like planets, are about to be revealed."   
       
   APL designed and built the spacecraft. The lab manages and operates the   
   mission for NASA's Science Mission Directorate in Washington.   
       
   Production Editor: Dr. Tony Phillips | Credit: Science@NASA   
       
   More Information   
   MESSENGER -- home page   
       
   See Mercury at Sunset --- Science@NASA   
       
   What's So Hard About Orbiting Mercury? -- Science@NASA   
       
       
       
   Regards,   
       
   Roger   
      
   --- D'Bridge 3.59   
    * Origin: NCS BBS (1:3828/7)