Forty-seven years ago today, the United States successfully orbited the world’s first geosynchronous communications satellite. This accomplishment marked the advent of today’s massive global communications market.
A geosynchronous orbit is one in which the orbital period of a satellite is equal to the time it takes the Earth to complete one revolution about its rotational axis. That is, the satellite completes one revolution around the Earth in slightly less than 24 hours. The altitude for such an orbit is 22,300 miles.
A geostationary orbit is a geosynchronous orbit that lies in the Earth’s equatorial plane. A peculiarity of a geostationary orbit is that the satellite’s position above the Earth remains fixed. Three (3) satellites equally spaced around the Earth in geostationary orbit are within direct line-of-sight of each other. Earth-based stations can use this arrangement to relay radio, television and other signals to any point on the globe.
The Hughes Aircraft Company in California began working on a concept for a geosynchronous satellite in early 1959. A trio of Hughes engineers (Harold Rosen, Thomas Hudspeth and Donald Williams) ultimately came up with a workable geosynchronous satellite design. It became known as Syncom – Synchronous Communications Satellite.
Syncom was cylindrical in shape. It measured 28 inches in diameter and had a height of 15.35 inches. The satellite weighed about 150 pounds fully fueled. Syncom’s external surface was covered with solar cells for power generation with nickel-cadmium batteries used for power storage. Syncom was spun about its symmetry axis for stabilization. Attitude control was provided by an array of nitrogen thrusters.
Syncom 1 was launched on Thursday, 14 February 1963 from Cape Canaveral, Florida. Unfortunately, the spacecraft’s signal was lost during the final boost to geosynchronous orbit. The loss of signal was attributed to an electrical failure. Later, ground-based telescope observations confirmed that the satellite had achieved a near-geosynchronous orbit.
Syncom 2 was launched from Cape Canaveral’s LC-17A at 14:38 UTC on Friday, 26 July 1963. A NASA Thor-Delta B provided the ride into orbit. Syncom’s 1,000-pound thrust apogee motor was used for the final ascent to a quasi-geosynchronous orbit. Over a period of several weeks, the satellite was nudged into a true geosynchronous orbit.
Syncom 2’s geosynchronous orbit was inclined 33 degrees with respect to the Earth’s equator. Thus, the resulting orbit was not geostationary. Coupled with the Earth’s rotation, the spacecraft actually moved in a figure-8 pattern over the globe that tracked 33 degrees north and south of the equator.
Syncom 2 went into active service on Friday, 16 August 1963. The satellite went on to perform brilliantly in its intended role as a communications link. A companion satellite, Syncom 3, was launched on Monday, 19 August 1964 and subsequently joined Syncom 2 in geosynchronous orbit. Significantly, Syncom 3 was used to broadcast the 1964 Tokyo Summer Olympics to America.
Syncom 2 and 3 continued to provide intercontinental communications across the Pacific Ocean until 1966. Increasingly more sophisticated and capable satellites followed. The communications revolution that Syncom started has grown to the point where there are now several hundred communications satellites operating in geosynchronous orbit about the Earth. While long silent, Syncom 2 and 3 continue to orbit the Earth today.