Some indeterminate period later he awoke. His mind still a little numbed by sleep he slipped the catch on his helmet and threw it back in order to take advantage of the bracing effect the sharp, thin air of Ganymede had displayed on the previous evening. He was totally unprepared for the furnace-like blast of heat that swept across his exposed features. He stood for a moment, stupefied, while the oven-heat dried the juices of his face and started to take on a blistering effect. Comprehension dawned magically and he snapped back the helmet and breathed with distinct relief the air supplied by his space suit which was scientifically kept at a pleasant temperature. The explanation was simplicity itself. The air cover of Ganymede was so thin, and its cloudless skies so clear, that the sun, though distant, beat down like old fury itself. He opened the door that led from the supply room into the pilot room. The long, pointed icicles which had formed the previous night were gone. The only clue to show that they had once existed was a rapidly rising cloud of steam from the steel floor. His glassite helmet misted swiftly as he walked through the room, then cleared slowly as he stepped out into the full glare of the sun. He could not help but admire the potency of this yellow star, even from a distance at which it appeared hardly larger than a standard sized base ball. He cupped one heavily encased hand over the top of his helmet to protect his eyes from the sun, and searched the skies thoroughly for any sign of a rescue ship. Sighting nothing he dropped his hand despondently to his side and stumbled thoughtfully along the rough terrain. His mind worked desperately, attempting to devise some feasible means of signaling the rescue parties which must, at this very moment, be combing the space lanes--searching for him. Some huge flare might be useful, but a simple glance about him revealed that the largest form of plant life, which might serve as fuel, were small grey mosses that grew on the underside of occasional outcropping rock formations. They were useless for anything but a tiny smudge fire. His mind turned back to his ship. Possibly there was something highly combustible aboard that might be used for a flare. His mind flitted thoughtfully over every item in the ship's supplies and retired with the conclusion that the anti-fire campaigns which had been conducted for so long on the inhabited planets were going too far! His only hope lay in the possibility that one of the rescue ships might briefly scan the surface of Ganymede with one of their telescopic vision plates and notice the gleaming wreck of his auxiliary space ship. That gave him an idea. Something he had once used in an old book. About a castaway on a desert island arranging rocks to spell out giant words in the hope that some passing airplane might see the message and land to investigate. Slim chance, but still nothing could be overlooked if he hoped for eventual rescue.