"How soon?" he wanted to know. "An hour or two," she said after conferring with Klev. "But he's not sure. This has never happened before in all the history of Mars." After a while Nick crept up to the rim of the rocky bowl, shivering as the cold, sand-laden wind whipped his exposed face. Both moons were below the horizon, leaving the desert in darkness relieved only by the stars and the lights of Central Camp. Phobos rose rapidly in the west, throwing long, distorted shadows over the red sands. And as the shadows grew shorter Nick thought he detected something. He rested his eyes and looked again. Yes, it was there, a darker, glimmering patch in a low spot a mile or so to the east. "Sue," he called excitedly. "It's starting." Quickly she was beside him, looking where he pointed. The patch of wet sand and standing water had grown to several hundred yards across when the orange flare of one of the night patrols flashed up from Central Camp. From several miles away the pilot sighted the unusual patch in the desert and swung to investigate. "Duck!" Nick warned as a flare blossomed into a circle of blinding whiteness. * * * * * Three times the rocket dived and circled the growing lake, and when it left as the last flare died it returned to the field at full throttle. Nick could imagine the pilot's almost incoherent radio reports. Water on Mars! A lake in the desert! The number of lights in Central Camp doubled while they watched. A gate in the barrier opened and three huge half-tracks roared out with searchlights glaring. They reached the pond, and even from the distance of their hiding place Susan and Nick could see the tiny figures of men as they rushed to the shore, touching the water, kneeling to dip their arms in it, even raising it to their lips. The green star of Earth rose over the horizon, and then the thing for which Nick had been hoping actually happened. All the lights of Central Camp went dim as power connections were changed. And then the flare of the great subatomic space beacon began to wink a message, the great beacon that depleted the power resources of the camp so badly that it was to be used only for messages of extreme urgency. But this was urgent indeed. Water on Mars! An hour, two, the coded news flamed into space. Nick and Susan crept down the slope, bone-chilled from their windswept watch, to tell the injured Martian what had happened. "If that doesn't bring a special ship out, then nothing will," Nick exulted. At dawn a procession of armored cars began to flow between the camp and the lake, and just before noon several hastily improvised tank trucks appeared, loaded and returned. No patrol rockets went out, for it seemed the entire schedule of the camp had been disrupted.