"Don't know. She was nearly overhead, going along fine, when we lost contact all of a sudden. One minute she was there, the next minute she was gone. We've lost the beam, and--just a second!" There was a pause at the other end, then Blake said: "We just got a report from some of the ground stations within range. Satellite Number Four has quit broadcasting altogether--there's no signal from her at all!" "I'll be right down," MacIlheny snapped. He hung up the phone and headed for the elevator. * * * * * It wasn't good. Number Four, like the other satellites, was in a nearly circular orbit high above the atmosphere of Earth. She should follow a mathematically predictable course, subject only to slight variations from the pull of the other satellites and the pull of the moon, plus the small perturbations caused by the changing terrain of the Earth beneath her. She'd have to be badly off course to be out of range of Beam Control. The elevator dropped MacIlheny down from the computer level to the monitor and control level. The men at the monitor screens didn't look up from their work as MacIlheny passed, but there was a feeling of tension in the air. The monitors knew what had happened. To the man in Bismarck, North Dakota, or the housewife in Tampa, Florida, the disappearance of the satellite meant nothing more than a slight irritation. If the program they were watching happened to be one that was shunted through Number Four, their screen had simply gone dark for a moment. Then, with apologies for "technical difficulties beyond our control," another program had been switched into the channel. For the businessman in San Francisco and the government official in New York, the situation was worse. Important intercontinental conferences were cut off in mid-sentence, and vital orders were left hanging in the air. For seven transcontinental stratoliners, the situation was almost tragic. The superfast, rocket-driven, robot-controlled ships, speeding their way through the lower ozonosphere, fifteen miles above the surface of the Earth, were suddenly without the homing beams they depended upon to guide them safely to their destinations. Their beam-detection instruments went into a search pattern while alarm bells shattered the quiet within. Passengers in the lounges and in the cocktail rooms looked suddenly wide-eyed. On one of the ships, there was a near panic when one fool screamed: "We're going to crash! Get parachutes!" Not until the flight captain caught the hysterical passenger on the chin with a hard right uppercut and explained that everything was in good order did the passengers quiet down. He didn't worry them by explaining that there were no parachutes aboard; at eighty thousand feet of altitude and a velocity of over forty miles per minute, a parachute would be worse than useless. Each of the stratoliners had to be taken over by the flight captain and eased down manually.