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Overview of the first American satellite, Explorer 1, and its launch on January 31, 1958.
Excerpt from “US Space Explorations” NASA Langley Research Center film L-703.
Public domain film from the US National Archives, slightly cropped to remove uneven edges, with the aspect ratio corrected, and one-pass brightness-contrast-color correction & mild video noise reduction applied.
The soundtrack was also processed with volume normalization, noise reduction, clipping reduction, and/or equalization (the resulting sound, though not perfect, is far less noisy than the original).
Explorer 1 was the first satellite of the United States, launched as part of its participation in the International Geophysical Year. The mission followed the first two satellites the previous year; the Soviet Union’s Sputnik 1 and 2, beginning the Cold War Space Race between the two nations.
Explorer 1 was launched on January 31, 1958 at 22:48 Eastern Time (equal to February 1, 03:48 UTC) atop the first Juno booster from LC-26 at the Cape Canaveral Missile Annex, Florida. It was the first spacecraft to detect the Van Allen radiation belt, returning data until its batteries were exhausted after nearly four months. It remained in orbit until 1970, and has been followed by more than 90 scientific spacecraft in the Explorer series.
Explorer 1 was given Satellite Catalog Number 4, and the Harvard designation 1958 Alpha 1, the forerunner to the modern International Designator…
Explorer 1 was the first successfully launched U. S. spacecraft. Launched late on 31 January 1958 (10:48 p.m. EST, or 03:48 UTC on 01 February) on an adapted Jupiter-C rocket, Explorer 1 carried instrumentation for the study of cosmic rays, micrometeorites, and for monitoring of the satellite’s temperature.
The Jupiter-C launch vehicle consisted of four propulsive stages. The first stage was an upgraded Redstone liquid-fueled rocket. The second, third, and fourth stage rockets consisted of eleven, three, and one (respectively) Sergeant motors. The satellite itself was the fourth stage of the Jupiter-C rocket. It was cylindrical, 2.03 m long and 0.152 m in diameter. Four whip antennas were mounted symmetrically about the mid-section of the rocket. The spacecraft was spin stabilized.
The 4.82 kg instrumentation package was mounted inside of the forward section of the rocket body. A single Geiger-Mueller detector was used for the detection of cosmic rays. Micrometeorite detection was accomplished using both a wire grid (arrayed around the aft section of the rocket body) and an acoustic detector (placed in contact with the midsection). Data from the instruments were transmitted continuously, but acquisition was limited to those times when the spacecraft passed over appropriately equipped ground receiving stations. Assembly of data proceeded slowly also due to the fact that the satellite’s spin-stabilized attitude transitioned into a minimum kinetic energy state, that of a flat spin about its transverse axis. This was deduced from the modulation of the received signal, which produced periodic fade-outs of the signal.
Explorer 1 was the first spacecraft to successfully detect the durably trapped radiation in the Earth’s magnetosphere, dubbed the Van Allen Radiation Belt (after the principal investigator of the cosmic ray experiment on Explorer 1, James A. Van Allen). Later missions (in both the Explorer and Pioneer series) were to expand on the knowledge and extent of these zones of radiation and were the foundation of modern magnetospheric studies.
