Detail View: NASA Astronomy Picture of the Day Collection: The First Explorer
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Title:
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The First Explorer
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Explanation:
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Fifty years ago (on January 31, 1958) the First Explorer [ http://www.nasa.gov/mission_pages/explorer/ ], was launched into Earth orbit [ http://www.redstone.army.mil/history/explorer/ welcome.html ] by the Army Ballistic Missile Agency. Inaugurating the era of space exploration for the United States, Explorer I [ http://history.nasa.gov/sputnik/expinfo.html ] was a thirty pound satellite that carried instruments to measure temperatures, and micrometeorite impacts, along with an experiment designed by James A. Van Allen [ http://history.nasa.gov/sputnik/vanallen.html ] 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 [ http://www.phy6.org/Education/wexp13.html ] -- an earth-encircling belt of high energy electrons and ions trapped in the magnetosphere [ http://www.phy6.org/Education/Intro.html ] now known as the Van Allen Radiation Belt [ http://www.phy6.org/Education/wradbelt.html ]. Explorer I ceased transmitting on February 28, 1958, but remained in orbit until March of 1970. Pioneering space scientist James Van Allen [ http://www.nasa.gov/vision/universe/features/ james_van_allen.html ] died on August 9th, 2006 at the age of 91.
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Credit and Copyright:
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Courtesy of Marshall Space Flight Center [ http://mix.msfc.nasa.gov/ ], NASA [ http://www.nasa.gov/home/index.html ]
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facet_when:
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1970
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facet_where:
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Goddard Space Flight Center (GSFC)
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facet_what:
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Earth
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facet_when_year:
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1958
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original url:
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http://antwrp.gsfc.nasa.gov/apod/ap080201.html
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UID:
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SPD-APOD-ap080201
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