Sixty Years of Space Exploration

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The launch of Explorer 1 marked the beginning of US spaceflight, as well as the scientific exploration of space.

Model of Explorer 1 at Jet Propulsion Laboratorium, Pasadena. Photo. NordicSpace

With the launch of Sputnik 1 the Soviet Union took a leading role in the space race, a challenge the Americans society not could fail to return. After some initial troubles in the start with the loss of the first satellite in the unsuccessful Vanguard launch late in 1957, the success finally came the last day of January 1958.

In the mid-1950s, both the United States and the Soviet Union were proceeding toward the capability to put a spacecraft in orbit. In 1954, an international council of scientists called for artificial satellites to be orbited as part of a worldwide science program called the International Geophysical Year (IGY), set to take place from July 1957 to December 1958. Both the American and Soviet governments seized on the idea, announcing they would launch spacecraft as part of the effort. Soon, a competition began between the US Army, the US Air Force and the US Navy to develop a US satellite and launch vehicle capable of reaching orbit.

Jet Propulsion Laboratory, JPL, in Pasadena, California, a military institution at that time, was chosen to prepare the three upper stages of the Jupiter-C launcher, where the uppermost stage included the satellite with the scientific payload.

University of Iowa physicist James Van Allen, whose instrument proposal had been chosen for the Vanguard satellite, was concerned about development issues on the project. Thus, he made sure his scientific instrument payload — a cosmic ray detector — would fit either launch vehicle. Meanwhile, although their project was officially mothballed, JPL engineers used a pre-existing rocket casing to quietly build a flight-worthy satellite, just in case it might be needed.

Unbeknownst to JPL, Werner von Braun, the German launcher specialist, and his team had also been developing their own satellite, but after some consideration, the Army decided that JPL would still provide the spacecraft. The result of that fateful decision was that JPL’s focus shifted permanently — from rockets, to what sits on top of them.

The spacecraft was launched on Friday, Jan. 31, 1958. An hour and a half later, a JPL tracking station in California picked up its signal transmitted from orbit. In keeping with the desire to portray the launch as the fulfillment of the US commitment under the International Geophysical Year, the announcement of its success was made early the next morning at the National Academy of Sciences in Washington, where Wiliam H Pickering, leader of JPL, Van Allen and von Braun on hand to answer questions from the media.

Following the launch, the spacecraft was given its official name, Explorer 1. (In the following decades, nearly a hundred spacecraft would be given the designation “Explorer.”) The satellite continued to transmit data for about four months, until its batteries were exhausted, and it ceased operating on May 23, 1958.

Later that year, when the National Aeronautics and Space Administration (NASA) was established by Congress. The JPL leader Wiliam H Pickering and Caltech worked to shift JPL away from its defence work to become part of the new agency. JPL remains a division of California Institute of Technology, Caltech, which manages the laboratory for NASA.

The beginnings of US space exploration were not without setbacks — of the first five Explorer satellites, two failed to reach orbit. However, the three that made it gave the world the first scientific discovery in space — the Van Allen radiation belts. These doughnut-shaped regions of high-energy particles, held in place by Earth’s magnetic field, may have been important in making Earth habitable for life. Explorer 1, with Van Allen’s cosmic ray detector on board, was the first to detect this phenomenon, which is still being studied today.

Explorer 1 re-entered Earth’s atmosphere and burned up on March 31, 1970, after more than 58,000 orbits.


Featured image:

Discovery  of the van Allen belt –  a result of the first satellite with scientific instrument onboard. Illustration: JPL