Hello All!   
      
   NASA Spacecraft Records 'Earthsong'    
      
   Oct. 1, 2012:  In space, they say, no one can hear you scream.    
      
   Nobody ever said anything about singing, though. A NASA spacecraft has just   
   beamed back a beautiful song sung by our own planet.    
      
   "It's called chorus," explains Craig Kletzing of the University of Iowa.    
   "This is one of the clearest examples we've ever heard." [Play the audio]    
      
   http://www.youtube.com/watch?v=MkTL2Ug6llE   
      
   A new ScienceCast video explores the eerie-sounding radio emissions that come   
   from our own planet. Play it   
      
   Chorus is an electromagnetic phenomenon caused by plasma waves in Earth's   
   radiation belts. For years, ham radio operators on Earth have been listening   
   to them from afar.  Now, NASA's twin Radiation Belt Storm Probes are traveling   
   through the region of space where chorus actually comes from--and the   
   recordings are out of this world.    
      
   "This is what the radiation belts would sound like to a human being if we had   
   radio antennas for ears," says Kletzing, whose team at the University of Iowa   
   built the "EMFISIS" (Electric and Magnetic Field Instrument Suite and   
   Integrated Science) receiver used to pick up the signals.    
      
   He's careful to point out that these are not acoustic waves of the kind that   
   travel through the air of our planet.  Chorus is made of radio waves that   
   oscillate at acoustic frequencies, between 0 and 10 kHz.  The magnetic search   
   coil antennas of the Radiation Belt Storm Probes are designed to detect these   
   kinds of waves.    
      
   "Chorus emissions are front and center for the Storm Probe mission," says   
   Kletzing. "They are thought to be one of the most important waves for   
   energizing the electrons that make up the outer radiation belt."    
      
   In particular, chorus might be responsible for so-called "killer electrons,"   
   high-energy particles that can endanger both satellites and astronauts.  Many   
   electrons in the radiation belts are harmless, with too little energy to do   
   damage to human or electronic systems.  But, sometimes, these electrons can   
   catch a chorus wave, like a surfer riding a wave on Earth, and gain enough   
   energy to become dangerous-or so researchers think.    
      
   http://science.nasa.gov/science-news/science-at-nasa/2012/30aug_rbsp/   
      
   The Radiation Belt Storm Probes are on a two-year mission to explore the Van   
   Allen Belts. [more] The Radiation Belt Storm Probes are on a mission to find   
   out for sure.     
      
   "The production of killer electrons is a matter of much debate, and chorus   
   waves are only one possibility," notes the Storm Probes' mission scientist   
   Dave Sibeck.    
      
   Launched in August 2012, the two probes are orbiting inside the radiation   
   belts, sampling electromagnetic fields, counting the number of energetic   
   particles, and listening to plasma waves of many frequencies.     
      
   "We hope to gather enough data to solve the mystery once and for all," says   
   Sibeck.    
      
   At the moment, the spacecraft are still undergoing their 60-day checkout phase   
   before the main mission begins. So far, things are checking out very well.    
      
   "One of things we noticed right away is how clear the chorus sounds in the   
   recording," notes Kletzing.  That's because our data is sampled at 16 bits,   
   the same as a CD, which has not been done before in the radiation belts. This   
   makes the data very high quality and shows that our instrument is very, very   
   healthy."    
      
   Eventually, Kletzing hopes to release unprecedented stereo recordings of   
   Earth's chorus.    
      
   "We have two spacecraft with two receivers," he says, "so a stereo recording   
   is possible."    
      
   Such a recording would not only sound wonderful, but also have real scientific   
   value.  "One of the things we don't know is how broad the region is over which   
   chorus occurs. The widely-separated `stereo capability' of the Storm Probes   
   will give us the ability to figure this out," he explains.    
      
   With a two-year mission planned for the Storm Probes, the chorus is just   
   getting started.     
      
      
   Author: Dr. Tony Phillips| Production editor: Dr. Tony Phillips | Credit:   
   Science@NASA   
      
      
   Regards,   
      
   Roger    
   --- timEd/386 1.10.y2k+   
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