Communications: Like the Red Queen

A new kind of communications satellite, Syncom II, built by Hughes Aircraft Co. for the National Aeronautics and Space Administration, soared up into space last week from Cape Canaveral. Instead of going into orbit not far above the earth, like famed Telstar I, it kept on climbing and climbing. When it touched an altitude of some 22,500 miles, a small rocket fired and pushed it into an almost circular orbit.

Three for the Globe. Like the Red Queen in Through the Looking Glass, the orbiting Syncom II keeps moving but gets nowhere. At its extreme height Syncom takes 24 hours to complete one orbit. Since this is the period of the earth’s rotation, it stays above the same point on the earth below. This “synchronous” orbit*—whence comes the name Syncom—has important advantages. Riding high, the satellite can relay messages by line-of-sight radio to more than one-third of the earth’s surface. Three satellites like it, properly spaced, can cover all the inhabited parts of the earth. Low-level communications satellites like Telstar I, whose orbit varied between 593 and 3,503 miles, do not cover nearly as much of the earth’s surface. Being so low, they can get along with less transmitting and receiving power, but many more of them must be used for world-wide communication. Another disadvantage of low-level satellites is that steerable radio antennas must follow them as they sweep rapidly across the sky. Synchronous satellites turning with the earth can be kept in view by fixed antennas, which are simpler to operate.

Syncom I, which was launched last February, went into near-perfect orbit, but its electronics system broke down, leaving it useless as a relay station. Last week’s successor, Syncom II, did better. As the satellite climbed toward orbit more than two hours after launch, the Navy communications ship Kingsport, anchored at Lagos, Nigeria, called it by microwave radio. Syncom II answered smartly, proving that its electronics gear was healthy. The satellite even bounced a recording of The Star-Spangled Banner back to the Kingsport.

Jockey for Position. Syncom II developed some drift after it went into orbit, as was expected, but in the wrong direction. The Kingsport next ordered Syncom to fire its hydrogen peroxide rocket to correct the slow eastward drift, and actually days will pass before Syncom’s delicate guidance apparatus will jockey it into an exactly synchronous orbit. Then it is supposed to swing gently in a north-south figure-eight pattern, crossing the equator over the Atlantic Ocean while radiomen below test how well it can relay messages between distant points on the distant earth.

* First suggested in 1946 by Science Fiction Writer Arthur C. Clarke.