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MEDIA RELATIONS OFFICE
JET PROPULSION LABORATORY
CALIFORNIA INSTITUTE OF TECHNOLOGY
NATIONAL AERONAUTICS AND SPACE ADMINISTRATION
PASADENA, CALIFORNIA 91109. TELEPHONE (818) 354-5011
http://www.jpl.nasa.gov http://www.jpl.nasa.gov/

Alan Buis 818/354-0474
Jet Propulsion Laboratory, Pasadena, Calif.    

Donald Savage 202/358-1727
NASA Headquarters, Washington                                         
     January 31, 2003

News Release: 2003-011

A 70,000-Carat U.S. Space 'Gem' Marks its Sapphire Anniversary
==============================================================

At a mere 31 pounds, it was tiny by today's spacecraft standards.  Yet
as it sprang skyward from Cape Canaveral, Fla., 45 years ago today,
January 31, 1958, aboard a Jupiter-C rocket, the Explorer 1 satellite
carried with it the enormous hopes and dreams of a Cold War America. 
The country was still reeling from the former Soviet Union's shocking
launches of Sputnik 1 and 2 the previous fall and the failure of
America's first Vanguard project launch the month before. 

The rocket was quickly swallowed by the night sky, and for 90 long
minutes President Eisenhower and America waited tensely to learn the
fate of the mission.  Finally, from a California desert tracking
station came the reply: "Goldstone has the bird."  America had
launched its first Earth-orbiting satellite and entered the Space Age.
 

Today we remember Explorer 1 for both its pioneering place in U.S.
space history and its immediate contributions to science as the
initial discoverer of the Van Allen Radiation Belts around Earth.  For
its developers, the people of NASA's Jet Propulsion Laboratory,
Pasadena, Calif. -- then operated by the U.S. Army -- those memories
are fond indeed. 

Dr. William Pickering, then JPL's director and leader of the project,
recalls the media's reaction to Explorer 1's success.  "We were told
there was going to be a press conference at the National Academy of
Sciences (in Washington).  About 2 a.m. we got into a car and drove
over to the Academy.  I can remember sitting in that car with (Dr.
James) Van Allen and (Dr. Wernher) von Braun -- just the three of us.
It was a cold, rainy night there in Washington and I think all three
of us wondered a little bit about what was going to happen and who was
going to be there at that hour of the morning.  They took us around to
the back door of the Academy and into the great hall.  It was
completely filled with people.  The media were there and very
enthusiastic when we got there...at the end of (the press conference),
I think all three of us realized that life was going to be different."

Explorer 1's official chronology spans to 1954, when the Army
authorized work on a joint Army-JPL program called Orbiter.  In 1955,
the U.S. government announced plans to launch a scientific satellite
during the International Geophysical Year (July 1957 to December
1958).  Orbiter competed head to head with another proposal from the
Navy called Vanguard.  Vanguard won, partly because it relied less on
military technology.  Despite the decision, JPL continued developing
some Orbiter technology for use in tests of reentry heat shields for
missiles.  After Sputnik's "shot heard 'round the world," Orbiter was
renamed Explorer and was approved for development as a backup program.

Then came Vanguard's failure and Explorer 1 suddenly found itself
front and center.

In just 84 days, Pickering and his JPL team worked with the U.S. Army
Ballistic Missile Agency in Huntsville, Ala.; top experts from U.S.
academia and the military; and legendary space luminaries such as
German rocket scientist Dr. Wernher von Braun to develop Explorer 1's
science package and communications system, as well as the high-speed
upper stages for the Jupiter-C rocket.  The work would mark JPL's
shift in emphasis from rockets to what sits on top of them. 

Pickering describes the mood around JPL during Explorer 1's
development as confident.  "We regarded ourselves as the experts in
the rocket business, having made both the Corporal and Sergeant
rockets for the Army and having developed most of the underlying
design features of the modern rocket, both liquids and solids," he
said. "We were confident."

Explorer 1's main science experiment was a cosmic ray detector built
by Dr. James Van Allen of the State University of Iowa.  It was
designed to measure the cosmic radiation environment in Earth's orbit
-- high-speed ions (atoms stripped of electrons) from the distant
universe.  It sought to measure the flow of cosmic ray ions of the
lowest energies, which are completely absorbed by the atmosphere and
can't be studied from the ground. 

Explorer 1 was launched into a highly elliptical orbit and carried no
onboard tape recorder.  Therefore, its data could only be collected
when it was within range of a tracking station, for just minutes at a
time.  The data collection soon revealed a mystery: at the low points
of the orbit the cosmic ray count was near the expected value, but at
the high portions of the orbit none were counted at all.  Van Allen
theorized the instrument might have been saturated by very strong
radiation from a belt of charged particles trapped in space by Earth's
magnetic field.  Two months later, Explorer 3 confirmed the existence
of these belts, which would become known as the Van Allen Radiation
Belts.

Explorer 1 made its final transmission on May 23, 1958.  It entered
Earth's atmosphere and burned up on March 31, 1970, after more than
58,000 orbits.  The Explorer program would go on to launch two more
successful missions.

JPL is managed for NASA by the California Institute of Technology in
Pasadena.

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