NAS and the First U.S. Earth Satellite

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).

Explorer I's successful launch was announced at a press conference held in the Great Hall of 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 for the IGY, working under NAS sponsorship, recommended that the US institute a scientific satellite program as part of its overall IGY program. 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 artificial earth satellite during the IGY.

Shortly after the announcement, the Academy put together the Technical Panel on the Earth Satellite Program (TPESP). TPESP'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 original membership included US National Committee Chairman Joseph Kaplan; USNC Secretary Hugh Odishaw; the Naval Research Laboratory's Homer 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 Astrophysical Lab.

In practical terms, the Academy's oversight of the scientific aspects of the satellite program meant that TPESP would determine which experiments would be flown aboard the satellites. 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 was formed under Van Allen. 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 in light of the Soviet success with Sputnik I, 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 been rejected in favor of Vanguard, was chosen as a backup launch vehicle. Consequently, the Technical Panel now was faced with the problem of allocating experiments to two different launch systems, with their correspondingly different requirements.

For use on Explorer I, TPESP allocated a cosmic ray detector, internal and external temperature sensors, a micrometeorite impact detector, and instruments to determine micrometeorite erosion.

With the highly publicized failure of Vanguard on 6 December 1957, the Jupiter-C, quickly modified to carry the Explorer I satellite, successfully launched on 31 January 1958. Explorer I 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 TPESP 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—but the Space Age had only begun.

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