NASA Spacecraft To Enter Large Asteroid's Orbit On July 15 July 14, 2011:   
       
   On July 15, NASA's ion-propelled Dawn probe will become the first spacecraft   
   to enter orbit around a main-belt asteroid. Dawn will orbit Vesta for one   
   Earth-year, studying the giant space rock at close range to help scientists   
   understand the earliest chapter of our solar system's history.   
       
   As Dawn approaches Vesta, surface details are coming into focus, as seen in a   
   recent image taken from a distance of about 26,000 miles (41,000 kilometers):   
   [...]   
   NASA's Dawn spacecraft obtained this image of giant asteroid Vesta on July 9,   
   2011, from a distance of about 26,000 miles (41,000 kilometers). Each pixel in   
   the image corresponds to roughly 2.4 miles (3.8 kilometers). [more]   
       
   Engineers expect the spacecraft to be captured into orbit at approximately 10   
   p.m. PDT Friday, July 15. They expect to hear from the spacecraft and confirm   
   that it performed as planned during a scheduled communications pass that   
   starts at approximately 11:30 p.m. PDT on Saturday, July 16. When Vesta   
   captures Dawn into its orbit, engineers estimate there will be approximately   
   9,900 miles (16,000 kilometers) between them. At that point, the spacecraft   
   and asteroid will be approximately 117 million miles (188 million kilometers)   
   from Earth.   
       
   "It has taken nearly four years to get to this point," said Robert Mase, Dawn   
   project manager at NASA's Jet Propulsion Laboratory in Pasadena, Calif. "Our   
   latest tests and check-outs show that Dawn is right on target and performing   
   normally."   
       
   Engineers have been subtly shaping Dawn's trajectory for years to match   
   Vesta's orbit around the sun. Unlike other missions, where dramatic propulsive   
   burns put spacecraft into orbit around a planet, Dawn will ease up next to   
   Vesta. Then the asteroid's gravity will capture the spacecraft into orbit.   
   However, until Dawn nears Vesta and makes accurate measurements, the   
   asteroid's mass and gravity will only be estimates. The Dawn team will refine   
   the exact moment of orbit capture over the next few days.   
       
   Launched in September 2007, Dawn will depart for its second destination, the   
   dwarf planet Ceres, in July 2012. The spacecraft will be the first to orbit   
   two bodies in our solar system.   
       
       
   Editor: Dr. Tony Phillips | Credit: Science@NASA   
       
   More Information   
   Dawn Journal -- penned by Dawn's chief engineer Marc Rayman   
       
   Does Asteroid Vesta Have a Moon?  -- from Science@NASA   
       
   Vesta--Is it Really an Asteroid?  -- from Science@NASA   
       
   For more information about Dawn, visit: http://www.nasa.gov/dawn and   
   http://dawn.jpl.nasa.gov . You can also follow Dawn on Twitter at:   
   http://www.twitter.com/NASA_Dawn .   
       
   Credits: Dawn's mission to Vesta and Ceres is managed by JPL for NASA's   
   Science Mission Directorate in Washington. Dawn is a project of the   
   directorate's Discovery Program, which is managed by NASA's Marshall Space   
   Flight Center in Huntsville, Ala.   
       
       
   Regards,   
       
   Roger   
      
   --- D'Bridge 3.63   
    * Origin: NCS BBS (1:3828/7)