Mission to Land on a Comet   
       
   Feb. 2, 2012: Europe's Rosetta spacecraft is en route to intercept a comet-   
   and to make history. In 2014, Rosetta will enter orbit around comet   
   67P/Churyumov-Gerasimenkoand land a probe on it, two firsts.   
       
   Rosetta's goal is to learn the primordial story a comet tells as it gloriously   
   falls to pieces.   
       
   Comets are primitive leftovers from our solar system's 'construction' about   
   4.5 billion years ago. Because they spend much of their time in the deep   
   freeze of the outer solar system, comets are well preserved-a gold mine for   
   astronomers who want to know what conditions were like back "in the beginning."   
       
   As their elongated orbits swing them closer to the sun, comets transform into   
   the most breathtaking bodies in the night sky. A European Space Agency mission   
   launched in 2004 with U.S. instruments on board, Rosetta will have a front-row   
   seat for the metamorphosis.   
       
   http://www.youtube.com/watch?v=FoePrO4-fGQ   
       
   An artist's concept of Rosetta in orbit while the mission's lander explores   
   the comet's surface. [more]   
       
   What we know of comets so far comes from a handful of flyby missions.   
       
   "In some ways, a flyby is just a tantalizing glimpse of a comet at one stage   
   in its evolution," says Claudia Alexander, project scientist for the U.S.   
   Rosetta Project at JPL. "Rosetta is different. It will orbit 67P for 17   
   months. We'll see this cometevolveright before our eyesas we accompany it   
   toward the sun and back out again."   
       
   Fierce solar heat will have a profound effect on Rosetta's target. "We'll   
   watch the comet start as just a little nugget in space and then become   
   something poetic and beautiful, trailing a vast tail."   
       
   At the moment, Rosetta is "resting up" for the challenges ahead. It's   
   hibernating, engaged in its high-speed chase while fast asleep.   
       
   Reveille is on or around New Year's Day 2014, when the spacecraft begins a   
   months-long program of self-checkups.   
       
   If all goes well, in August of the same year, Rosetta will enter orbit around   
   67P's nucleus and begin scanning its surface for a landing site. Once a site   
   is chosen, the spacecraft will descend as low as 1 km to deploy the lander.   
       
   The lander's name is "Philae" after an island in the Nile, the site of an   
   obelisk that helped decipher-you guessed it-the Rosetta Stone.   
       
   Touchdown is scheduled for November 2014, when Philae will make the first ever   
   controlled landing on a comet's nucleus.   
       
   "When we land, the comet could already be active!" says Alexander. Because a   
   comet has little gravity, the lander will anchor itself with harpoons. "The   
   feet may drill into something crunchy like permafrost, or maybe into something   
   rock solid," she speculates.   
       
   Once it is fastened, the lander will commence an unprecedented first-hand   
   study of a comet's nucleus.  Among other things, it will gather samples for   
   examination by automatic onboard microscopes and take panoramic images of the   
   comet's terrain from ground level.   
       
   Meanwhile, orbiting overhead, the Rosetta spacecraft will be busy, too.   
   Onboardsensors will map the comet's surface and magnetic field, monitor the   
   comet's erupting jets and geysers, measure outflow rates, and much more.   
   Together, the orbiter and lander will build up the first 3D picture of the   
   layers and pockets under the surface of a comet.   
       
   The results should tell quite a story indeed.   
       
       
   Author:Dauna Coulter  | Editor: Dr. Tony Phillips | Credit: Science@NASA   
       
   More Information   
       
   Rosetta at a Glance -- from the European Space Agency   
       
   European Space Agency -- home page   
       
   Comet Corpses in the Solar Wind -- Science@NASA   
       
   Some Comets Like it Hot -- Science@NASA   
       
       
   Regards,   
       
   Roger   
      
   --- D'Bridge 3.73   
    * Origin: NCS BBS (1:3828/7)