Science: Atlas in Orbit

The Atlas that went into orbit (see NATIONAL AFFAIRS) is technically called a 1½-stage rocket—a single engine plus ground-fired boosters. When its two booster engines stop firing, the main body, propelled by the central sustainer engine, flies out of the short cylindrical after-section that carries the boosters (see diagram). With the boosters gone, the sustainer engine has less dead weight to carry into space. In this particular model, the sustainer was designed to burn 13 seconds longer than in the regular models. Without this extra thrust, needed to put the Atlas into orbit, it would have plunged into the Atlantic 6,000 miles from Cape Canaveral.

Like other Atlases, this one was guided by a wondrously sophisticated ground computer. Before blastoff, the Atlas’ internal guidance mechanism was instructed to follow a programed course. As it rose, the Atlas reported by radio on how it was doing. Digesting this information almost instantly, the ground computer radioed back to the Atlas the proper corrections for making its actual course conform to the programed one. These course corrections were made by controllable vernier rockets and slight changes of the direction in the thrust of the main engine. When the Atlas had climbed above nearly all of the atmosphere, the computer told it to turn its nose parallel to the earth’s surface. Other U.S. satellites were kicked into orbit by firing a final rocket from the ground at a calculated altitude. Atlas was the first satellite to be steered along the whole flight with the same engine, thus marked a major advance in controlled flight of ballistic missiles.

Sputnik Rivals. The Atlas, with its nearly 4½ tons, was widely hailed as the heaviest object to be put in orbit, but the Russians were quick to put in a counterclaim. Leonid Sedov, often an official spokesman for Soviet missilemen, declared that each of the three Soviet carrier rockets that orbited the earth weighed considerably more. These weights are not known accurately outside Russia, since the Russians maintain that only the instrument payload is important. The payload of the dog-carrying Sputnik II (instruments, dog, transmitter, etc.) weighed 1,120 lbs., v. the Atlas’ 200 plus. Sputnik III’s payload weighed 2,134 lbs.

If not the heaviest, Atlas is probably the biggest object that has orbited. Overall, it is 85 ft. long, 10 ft. in diameter. It is a delicate beast. Its main body is a fuel tank of bubble-thin metal. This bulk makes it easy to see, but it also creates atmospheric drag. For this reason, its estimated life is only 20 days.

Most exotic cargo aboard the Atlas are two recorder-transmitters. Carried in a special pod on the rocket’s side, the instruments weigh an estimated 100 lbs. each, are capable of receiving, recording, and rebroadcasting messages on signal from the ground. President Eisenhower’s voice, recorded on tape ahead of time, was sent up in the instrument package. After the Atlas made twelve trips around the earth, a radio station at Cape Canaveral gave it a coded signal that triggered one of its transmitters. Down from space came the President’s message, scratchy but intelligible.

For more than a day the Atlas stayed too far from the U.S. for further experiments. Then it passed near a tracking station in California, which first tried to extract from it a second broadcast of Eisenhower’s voice. The satellite tried to comply, but reception was poor. The station then radioed a signal that told the satellite to record a fresh message. The satellite obeyed, making a tape of a Teletype version of President Eisenhower’s message. As it swept eastward at 17,000 m.p.h., a station in Texas gave it the playback signal. Down from space came the message recorded a few minutes earlier over California.

Next time around, the full experiment worked. On command, the satellite erased the Teletype message and recorded a voice message: “This is Prado Dam. United States Army Signal Research and Development Laboratory, Corona, Calif. We are transmitting the President’s message . . .” Queried by the tracking station in Texas, the satellite repeated the message “loud and clear.”

The experiment proved that men on earth will be able to talk to men in space vehicles of the future. Looking confidently ahead, Defense officials declare that even this huge achievement is “as primitive as a baby’s first words.” Future satellites will be able to carry far more intricate electronic gear, may provide many circuits for telephone and even television transmissions around the shrinking world.