Stuttering Discoverer

Two days before Pioneer IV's successful takeoff, the Air Force launched its first Discoverer satellite from Vandenberg Air Force Base in California. Discoverer was the U.S.'s first attempt to put a satellite into polar orbit, which would make possible surveillance of the whole of the earth's surface. The booster, a

Thor ICBM, and the second stage, a 19-ft. liquid-fuel job built by Lockheed, apparently worked well. Watchers assumed that the bird, which consisted of the 1,300-lb. second stage with a 40-lb. instrument payload, had gone into orbit over the South Pacific.

But something went wrong. A Navy range ship stationed 900 miles to the south reported only weak signals from the bird passing overhead. Then came silence. The elaborate Air Force tracking system, set up across the North Pacific especially for the Discoverer series, heard nothing for 1 hr. 30 min. Then a Hawaiian station heard a brief, faint signal. After five more hours of silence, Air Force stations in Alaska and the U.S. began to pick up sporadic signals. Last week, nearly five days after launch, the Department of Defense felt able to announce that Discoverer I was in polar orbit. But it had not been spotted visually, perhaps because its orbit carried it over the world's inhabited areas in bright daylight or darkness, when it is hard to see. The nine-station radio fence that spans the U.S. and is supposed to detect any silent satellite had reported no sign of it.

According to the Air Force, the fault was not in the launching equipment but in the instrumentation of the payload. One theory is that the transmitter worked weakly or intermittently. Another is that the satellite's stabilizing system failed, allowing the satellite to tumble over and over. This might make its directional radio signals hard to receive on earth.