Escape of the Destructive Electrons   
       
   Dec. 14, 2015:  Warning:  Earth is surrounded by electrons that can be   
   disruptive to our technology.   
       
   A population of high-energy electrons inhabits the Van Allen radiation belts   
   high above Earth.  While these electrons pose no danger to humans on Earth's   
   surface, where we are protected by the atmosphere, they have been blamed for   
   many spacecraft failures.  Electron swarms can penetrate and electrify the   
   hulls of satellites and short-circuit sensitive electronics.  Avoiding them is   
   a good idea.   
       
   To avoid them, though, you have to figure out where they are.  And that's a   
   problem because these electrons can be very elusive.   
       
   http://tinyurl.com/zr3vdx9   
       
   The Van Allen belts were discovered in 1958 and their discovery was one of the   
   earliest scientific achievements of the space age.  During solar storms,   
   high-energy electrons in the belts have been known to vanish - only to return   
   a few hours later. This strange phenomenon was first spotted in the 1960s, and   
   it has puzzled physicists ever since.   
       
   In 2012, NASA launched the Radiation Belt Storm Probes (RBSP), which have   
   since been renamed the Van Allen Probes.  Rather than avoiding the radiation   
   belts, these heavily-shielded spacecraft regularly fly right into them. Their   
   mission is to discover what makes the belts so dangerous and, moreover, so   
   unpredictable.   
       
   In the few years since they have launched, the Van Allen Probes have made many   
   discoveries-such as the occasional existence of a third radiation belt that no   
   one knew about before.  The mystery of the vanishing electrons, however, has   
   not been fully solved.   
       
   A popular idea among researchers is that the electrons precipitate into   
   Earth's upper atmosphere, depositing their energy high above our planet's   
   surface.  But how?  What could trigger such an electron "rainfall"?   
       
   To answer this question, the Van Allen Probes needed help-from below.   
       
   Since 2013, an international team of researchers led by physicist Robyn Millan   
   of Dartmouth College have been launching research balloons from Antarctica,   
   each standing more than 8 stories tall.  These mammoth balloons ride   
   circumpolar winds around the South Pole, floating as much as 40 km high as   
   they look for signs that electrons are penetrating the atmosphere overhead.   
       
   The name of the program is "BARREL"-short for Balloon Array for Radiation-belt   
   Relativistic Electron Losses.   
       
   The electron rainfall, when it occurs, reveals itself by a telltale glow of   
   X-rays. These X-rays are the by-product of electrons striking atoms and   
   molecules in the upper atmosphere.  BARREL's balloons are equipped with a   
   payload of sensors to observe such emissions.   
       
   Occasionally, the balloons are in flight when the Van Allen Probes pass   
   overhead. Such a conjunction is perfect for this research; the two Probes can   
   track the electrons from above while the balloons do so from below.   
       
   There were two such conjunctions on January 3rd and 6th of 2014-and   
   researchers put them to good use.   
       
   Working together, the Van Allen Probes and BARREL were able to piece together   
   a means of escape.   
       
    "Electrons were gradually eroded away over the course of several days [in   
   part] by interaction with plasmaspheric `hiss,'" wrote Millan and colleagues   
   in a letter published in Nature.   
       
   "Plasmaspheric hiss" is a type of electromagnetic radiation or "plasma wave" ,   
   that can scatter these high-energy electrons down toward Earth. Looking up   
   from Antarctica, BARREL could measure the electrons losing their energy in the   
   form of relatively harmless X-rays. The plasmaspheric hiss was simultaneously   
   observed by both Van Allen Probe satellites.   
       
   There may be other ways for the electrons to escape the Van Allen belts so the   
   mystery is not fully solved.  As 2015 unfolds, the BARREL team has completed a   
   third campaign of balloon flights over Sweden in search of more clues.   
       
       
   Regards,   
       
   Roger   
      
   --- DB 3.99 + Windows 10   
    * Origin: NCS BBS - Houma, LoUiSiAna (1:3828/7)