 What is the most precious commodity on the moon?
The meteor, a pebble, a little larger than a match head, traveled through space and time since it came into being. The light from the star that died when the meteor was created fell on Earth before the first lungfish ventured from the sea. In its last instant, the meteor fell on the Moon. It drilled a small, neat hole through the casing of the steam turbine, and volitized upon striking the blades. The shaft tried to tie itself into a knot, and the blades, damaged and undamaged were spit through the casing. The shadow line between day and night could be seen from the Moon to be drifting across Australia. When he was broke, which was usually, he used his tractor to haul uranium ore and metallic sodium from the mines at Potter's dike to Williamson Town, where the rockets landed. Once he followed a stampede to Yellow Crater, where he thought for a while that he had a fortune in chromium. The chromite petered out in a month and a half, and he was lucky to break even. Evans was about three hundred miles east of Williamson Town, the site of the first landing on the Moon. His drinking water—kept separate from the water in the reactor—might conceivably last just as long. But his oxygen was too carefully measured; there was a four-day reserve. Four days reserve—plus one is five—plus sixteen days normal supply equals twenty-one days to live. In seventeen days he might be missed, but in seventeen days it would be dark again, and the search for him, if it ever began, could not begin for thirteen more days. By the light of this, he reinspected the steam system, and found about three gallons of water frozen in the condenser. This one had a tank and coils of tubing in the center of a curved reflector that was positioned to radiate the heat of the steam into the cold darkness of space. When the meteor pierced the turbine, the water in the condenser began to boil. If there was any water in the boiler, it would operate the engine that drove the generator. It was three days' supply of water, if it had been carefully used. It was one day's supply if used wastefully. It was ostentatious luxury for a man with a month's supply of water and twenty-one days to live. It was an incredibly brilliant disk in a black sky. This was to allow the air-conditioning system to function properly, and to prevent air loss in case of the highly improbable meteor damage.
 Water
 Water  Oxygen  Natural gas  Chromite ore