Record Setting Asteroid Flyby   
       
   Jan. 28, 2013:  Talk about a close shave. On Feb. 15th an asteroid about half   
   the size of a football field will fly past Earth only 17,200 miles above our   
   planet's surface. There's no danger of a collision, but the space rock,   
   designated 2012 DA14, has NASA's attention.   
       
   "This is a record-setting close approach," says Don Yeomans of NASA's Near   
   Earth Object Program at JPL. "Since regular sky surveys began in the 1990s,   
   we've never seen an object this big get so close to Earth."   
       
   http://www.youtube.com/watch?v=GwidzVHvbGI   
       
   A new ScienceCast video previews the close flyby of asteroid 2012 DA. Play it   
   Earth's neighborhood is littered with asteroids of all shapes and sizes,   
   ranging from fragments smaller than beach balls to mountainous rocks many   
   kilometers wide. Many of these objects hail from the asteroid belt, while   
   others may be corpses of long-dead, burnt out comets. NASA's Near-Earth Object   
   Program helps find and keep track of them, especially the ones that come close   
   to our planet.   
       
   2012 DA14 is a fairly typical near-Earth asteroid. It measures some 50 meters   
   wide, neither very large nor very small, and is probably made of stone, as   
   opposed to metal or ice.  Yeomans estimates that an asteroid like 2012 DA14   
   flies past Earth, on average, every 40 years, yet actually strikes our planet   
   only every 1200 years or so.   
       
   The impact of a 50-meter asteroid is not cataclysmic--unless you happen to be   
   underneath it. Yeomans points out that a similar-sized object formed the mile   
   wide Meteor Crater in Arizona when it struck about 50,000 years ago. "That   
   asteroid was made of iron," he says, "which made it an especially potent   
   impactor." Also, in 1908, something about the size of 2012 DA14 exploded in   
   the atmosphere above Siberia, leveling hundreds of square miles of forest.   
   Researchers are still studying the "Tunguska Event" for clues to the impacting   
   object.   
       
   "2012 DA14 will definitely not hit Earth," emphasizes Yeomans. "The orbit of   
   the asteroid is known well enough to rule out an impact."   
       
   http://neo.jpl.nasa.gov/news/news174.html   
       
   A schematic diagram of the Feb 15th flyby. MoreEven so, it will come   
   interestingly close. NASA radars will be monitoring the space rock as it   
   approaches Earth closer than many man-made satellites. Yeomans says the   
   asteroid will thread the gap between low-Earth orbit, where the ISS and many   
   Earth observation satellites are located, and the higher belt of   
   geosynchronous satellites, which provide weather data and telecommunications.   
       
   "The odds of an impact with a satellite are extremely remote," he says. Almost   
   nothing orbits where DA14 will pass the Earth.   
       
   NASA's Goldstone radar in the Mojave Desert is scheduled to ping 2012 DA14   
   almost every day from Feb. 16th through 20th. The echoes will not only   
   pinpoint the orbit of the asteroid, allowing researchers to better predict   
   future encounters, but also reveal physical characteristics such as size,   
   spin, and reflectivity. A key outcome of the observing campaign will be a 3D   
   radar map showing the space rock from all sides.   
       
   During the hours around closest approach, the asteroid will brighten until it   
   resembles a star of 8th magnitude. Theoretically, that's an easy target for   
   backyard telescopes. The problem, points out Yeomans, is speed. "The asteroid   
   will be racing across the sky, moving almost a full degree (or twice the width   
   of a full Moon) every minute. That's going to be hard to track." Only the most   
   experienced amateur astronomers are likely to succeed.   
       
   Those who do might experience a tiny chill when they look at their images.   
   That really was a close shave.   
       
   For more information about 2012 DA and other asteroids of interest, visit   
   NASA's Near-Earth Object Program web site: http://neo.jpl.nasa.gov   
       
       
   Author: Dr. Tony Phillips |Production editor: Dr. Tony Phillips | Credit:   
   Science@NASA   
       
       
   Regards,   
       
   Roger   
      
   --- D'Bridge 3.9   
    * Origin: NCS BBS - Houma, LoUiSiAna (1:3828/7)