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Credit & Copyright: Courtesy of Marshall  
Space Flight Center,  
NASA  
  
  
Explanation:
Fifty years ago  
(on January 31, 1958)  
the  
First Explorer, was  
launched into Earth orbit  
by the Army Ballistic Missile Agency.  
  
Inaugurating the era of space exploration for the United States,  
Explorer I  
was a thirty pound satellite that  
carried instruments to measure temperatures,  
and micrometeorite impacts, along with an experiment designed by  
James A.  
Van Allen to measure  
the density of electrons and ions in space.  
  
The measurements made by Van Allen's experiment led to an unexpected and  
startling  
discovery -- an earth-encircling belt of high energy electrons  
and ions trapped in the  
magnetosphere  
now known as the  
Van  
Allen Radiation Belt.  
  
Explorer I ceased transmitting on February 28, 1958, but  
remained in orbit until March of 1970.  
  
Pioneering space scientist  
James Van Allen died on August 9th,  
2006 at the age of 91.  
  
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NASA Web Site Statements, Warnings, and Disclaimers
NASA Official: Jay Norris. Specific rights apply.
A service of: LHEA at NASA / GSFC
& Michigan Tech. U.
Based on Astronomy Picture
Of the Day
Publications with keywords: satellite - explorer 1
Publications with words: satellite - explorer 1
See also:

