NASAのインスタグラム(nasa) - 11月14日 04時37分

Throwback Thursday: How Satellite Laser Ranging Got its Start

Fifty years ago, NASA announced the first successful tracking of a satellite using a laser, a technique now standard for precisely determining satellite orbits.

The landmark experiments were conducted at NASA’s Goddard Space Flight Center in Greenbelt, Maryland, and the results publicized on Nov. 13, 1964. Before the end of the decade, the technique had gone international, with five stations in the U.S. and France equipped for laser ranging. These days, more than 40 stations are in operation, located on every continent except Antarctica.

The appeal of these measurements is their precision. In 1964, microwave radars for tracking satellites had a range accuracy up to about 250 feet (75 meters). NASA’s initial announcement about satellite laser ranging reported a range accuracy up to about 10 feet (3 meters) – about 25 times better.

In this image, physicist Henry Plotkin examines the retroreflector array for Beacon Explorer A before integration onto the 1964 satellite.

Image Credit: Courtesy of Henry Plotkin
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