Hello All!   
      
   Big Asteroid Tumbles Harmlessly Past Earth        
      
   Dec. 12, 2012: This week, NASA's Goldstone radar is tracking a large asteroid   
   as it passes by Earth, and obtaining unusually clear images of the tumbling   
   space rock.    
      
   "There is no danger of a collision with Earth," says Lance Benner of NASA's   
   Near Earth Object Program. "At closest approach on Dec. 12th, asteroid 4179   
   Toutatis will be 7 million km away or 18 times farther than the Moon."    
      
   http://echo.jpl.nasa.gov/asteroids/Toutatis2012/Toutatis2012_planning.html   
      
   A sampling of Goldstone radar images obtained during the asteroid Toutatis's   
   Dec. 2012 flyby. [more]    
      
   Asteroid Toutatis is well known to astronomers; it passes by Earth's orbit   
   every 4 years. Measuring 4.5 km in length, it is one of the largest known   
   potentially hazardous asteroids (PHAs), and its orbit is inclined less than   
   half-a-degree from Earth's. No other kilometer-sized PHA moves around the Sun   
   in an orbit so nearly coplanar with our own.  This makes it an important   
   target for radar studies.    
      
   NASA's Goldstone radar in the Mojave Desert will be pinging the space rock   
   every day from Dec. 4th through 22nd.  The echoes highlight the asteroid's   
   topography and improve the precision with which researchers know the   
   asteroid's orbit.    
      
   "We already know that Toutatis will not hit Earth for hundreds of years," says   
   Benner.  "These new observations will allow us to predict the asteroid's   
   trajectory even farther into the future."    
      
   Benner and colleagues are particularly excited about a new digital imaging   
   system at Goldstone that could reveal never-before-seen details on the   
   asteroid's surface. "Using the new system, we can now image the asteroid's   
   surface with 2 to 5 times finer resolution than previous flybys," he says. "We   
   may we see something new on Toutatis."    
      
   The asteroid is already remarkable for the way that it spins. Unlike planets   
   and the vast majority of asteroids, which rotate in an orderly fashion around   
   a single axis, Toutatis travels through space tumbling like a badly thrown   
   football (movie).  One of the goals of the radar observations is to learn more   
   about the asteroid's peculiar spin state and how it changes in response to   
   tidal forces from the Sun and Earth.    
      
   http://gssr.jpl.nasa.gov/   
      
   NASA's 70-meter diameter Goldstone radar. [more] It's probably no coincidence   
   that the tumbling asteroid is elongated and lumpy.     
      
   "Toutatis appears to have a complicated internal structure," says radar team   
   member Michael Busch of the National Radio Astronomy Observatory. "Our radar   
   measurements are consistent with the asteroid's little lobe being ~15% denser   
   than the big lobe; and they indicate 20% to 30% over-dense cores inside the   
   two lobes."    
      
   This raises the interesting possibility that asteroid Toutatis is actually a   
   mash up of smaller space rocks.  "Toutatis could be re-accumulated debris from   
   an asteroid-asteroid collision in the main belt," he says.   The new   
   observations will help test this idea.    
      
   Busch points out that the upgraded Goldstone imaging system will produce data   
   with a resolution of 3.75 meters per pixel.  "We'll be putting hundreds of   
   thousands of pixels across the asteroid's surface."    
      
   What will so much resolution reveal? Stay tuned for updates from Science@NASA.    
      
      
   Author: Dr. Tony Phillips| Production editor: Dr. Tony Phillips | Credit:   
   Science@NASA   
      
      
   Regards,   
      
   Roger    
   --- timEd/386 1.10.y2k+   
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