The yellow sands of the spaceport stretched, glaring and empty, in every direction. There was no sign of life from the little group of buildings a mile away. In the control room of the tall, round-nosed starship, technicians labored and officers conferred while the red needles that showed rocket tube temperatures sank slowly toward zero on their dials. "Maybe Earth's depopulated, Tom," suggested John Gray, the executive officer. He ran his fingers through close-cropped red hair and peered throug