On 31 January 1958, a US Army Jupiter-C rocket launched Explorer I, the first American
satellite, into earth orbit. The success of Explorer I, coming three months after the
Soviet Union successfully orbited Sputnik I, the first artificial earth satellite,
represented the highlight of US participation in the International Geophysical Year (IGY).
The successful launch was announced at a press conference held at the National Academy of
Sciences building. This was appropriate, as the US earth satellite effort was initiated
under the auspices of the Academy. Following an October 1954 meeting of the International
Council of Scientific Unions (ICSU) in Rome, the US National Committee (USNC) for the IGY,
working under NAS sponsorship, recommended that the US institute a scientific satellite
program as part of its participation in the IGY. Shortly thereafter, NAS president Detlev
Bronk, along with National Science Foundation director Alan Waterman, took the satellite
proposal to the US government. It was approved, and on 29 July 1955 the Eisenhower
Administration announced the US goal of orbiting an earth satellite during the IGY.
Shortly after the announcement, the Academy put together a Technical Panel on the Earth
Satellite Program. The Technical Panel's mission was to oversee the scientific aspects
of the satellite project, as well as those aspects concerning public information and
institutional relations. Chaired by Richard Porter, the Technical Panel's
included UNSC Chairman Joseph Kaplan; USNC Secretary Hugh Odishaw; the Naval Research Laboratory's
Homer E. Newell Jr.; William Pickering of the California Institute of Technology's Jet Propulsion
Laboratory; Athelstan Spilhaus of the University of Minnesota; Princeton University's Lyman Spitzer,
Jr.; James Van Allen of the State University of Iowa; and Fred Whipple of the Smithsonian Institution's
In practical terms, the Academy's oversight of the scientific aspects of the satellite program
meant that the Technical Panel would determine which experiments would be conducted. Proposals
for appropriate experiments needed to be obtained, and to that purpose the Technical Panel's
Van Allen and Odishaw organized a symposium titled "The Scientific Aspects of Earth Satellites,"
which was held at the January 1956 meeting of the Upper Atmosphere Rocket Research Panel.
Given the resulting influx of proposals, it was next necessary to come up with a way of
evaluating them, and thus a Working Group on Internal Instrumentation under Van Allen was
formed for that purpose. The Working Group was also charged with recommending which experiments
should have priority for placement on the satellites. Not long after, a second Working Group,
on Tracking and Computation, was set up under Pickering to help in the evaluation of experiments.
The responsibility for assigning appropriate experiments originally was relatively
straightforward. Experiments could be selected and then distributed among the series
of Vanguard launches that, according to the original plan, would put them into orbit.
But this was soon complicated by the fact that after the Soviet success with Sputnik I
in October 1957, the US Government accelerated its own satellite effort by, in effect,
authorizing two different programs. Besides the Navy's Vanguard program, which had originally
been selected for launch of the US satellite, the Army's Jupiter-C rocket, a forerunner of
which had lost out to Vanguard, was chosen as a backup. Consequently, Technical Panel now
with the problem of allocating experiments to two different launch systems, with
their correspondingly different requirements.
For use on Explorer I, the Technical Panel allocated a cosmic ray detector, internal and
external temperature sensors, a micrometeorite impact detector, and instruments to determine
With the highly publicized failure of Vanguard on 6 December 1957, the Jupiter-C, quickly
modified to carry the Explorer I satellite with its package of instruments, successfully
launched on 31 January 1958. This satellite is credited with having made the most important
discovery of the IGY -- the discovery of one of the belts of radiation surrounding the earth,
subsequently named the Van Allen Belts after Technical Panel member James Van Allen, the
scientist who identified them.
Explorer I was only the first of a series of satellites launched as part of the US IGY earth
satellite program. With the 13 October 1959 launch of Explorer VII, that program came to an
end -- and the Space Age had begun.
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