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How Satellites Work


When Were Satellites Invented?

Newton may have worked through the mental exercise of launching a satellite, but it would take a while before we actually accomplished the feat. One of the early visionaries was sci-fi writer Arthur C. Clarke. In 1945, Clarke suggested that satellites could be placed into orbit so that they moved in the same direction and at the same rate as the spinning Earth. These so-called geostationary satellites, he proposed, could be used for communications.

Many scientists didn't fully embrace Clarke's idea -- until Oct. 4, 1957. That's when the Soviet Union launched Sputnik 1, the first man-made satellite to orbit Earth.Sputnik was a 23-inch (58-centimeter), 184-pound (83-kilogram) metal ball. Although it was a remarkable achievement, Sputnik's contents seem meager by today's standards:

On the outside of Sputnik, four whip antennas transmitted on shortwave frequencies above and below what is today's citizens-band (27 megahertz). Tracking stations on the ground picked up the radio signals and confirmed that the tiny satellite had survived the launch and was successfully tracing a path around our planet. A month later, the Soviets placed a companion craft, Sputnik 2, in orbit. Nestled inside the capsule was a dog by the name of Laika.

In December 1957, desperate to keep up with their Cold War counterparts, American scientists tried to carry a satellite into orbit aboard a Vanguard rocket. Unfortunately, the rocket crashed and burned on the launchpad. Shortly after, on Jan. 31, 1958, the U.S. finally matched the success of the Soviets by using a plan adopted by Wernher von Braun, which called for a U.S. Redstone rocket to propel a satellite -- Explorer 1 -- into Earth's orbit. Explorer 1 carried instrumentation to detect cosmic rays and revealed, in an experiment led by James Van Allen of the University of Iowa, a much lower cosmic ray count than expected. This led to the discovery of two doughnut-shaped zones (eventually named for Van Allen) filled with charged particles trapped by Earth's magnetic field.

Bolstered by these successes, several companies raced to develop and deploy satellites in the 1960s. One of these was Hughes Aircraft and its star engineer Harold Rosen. Rosen led a team that turned Arthur C. Clarke's concept -- a communications satellite positioned in Earth's orbit so it could bounce radio waves from one location to another -- into a feasible design. In 1961, NASA gave Hughes a contract to build the Syncom (synchronous communication) series of satellites. In July 1963, Rosen and his colleagues watched as Syncom 2 soared into space and navigated into a (roughly) geosynchronous orbit. President Kennedy used the new system to have a conversation with the Nigerian prime minister in Africa (you can listen here). This was followed by Syncom 3, which could actually broadcast television.

The age of satellites had begun.