 Moon inhabitants must make all of the following considerations regarding their equipment EXCEPT:
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. 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. It was just before sunset on a spring evening in September in Sydney. The shadow line between day and night could be seen from the Moon to be drifting across Australia. Evans, who had no watch, thought of the time as a quarter after Australia. 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. 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. This boiling lowered the temperature, and the condenser demonstrated its efficiency by quickly freezing the water in the tank. Evans sealed the turbine from the rest of the steam system by closing the shut-off valves. If there was any water in the boiler, it would operate the engine that drove the generator. Then, if the pump wasn't blocked by ice, it would return the water to the boiler. Carefully he poured a cup of his drinking water into a pipe that led to the boiler, and resealed the pipe. It was three days' supply of water, if it had been carefully used. It was ostentatious luxury for a man with a month's supply of water and twenty-one days to live. They might have appeared to waver slightly, if they were behind outflung corona flares. He felt a little guilty about this, because he had ordered that all doors in the survey building should remain closed except when someone was passing through them. This was to allow the air-conditioning system to function properly, and to prevent air loss in case of the highly improbable meteor damage.
 Protection from extreme temperatures
 Protection from meteor showers and volcanic eruptions  The cost of rare materials imported from Earth  Protection from extreme temperatures  The ability to function with minimal water use