 What is Evans' primary dilemma?
Like when there's no use trying—when it's time to give up because it's hopeless.... 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. The shaft tried to tie itself into a knot, and the blades, damaged and undamaged were spit through the casing. It was two days to sunrise, where Evans stood. 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 a prospector, and like all prospectors, a sort of jackknife geologist, selenologist, rather. Once he followed a stampede to Yellow Crater, where he thought for a while that he had a fortune in chromium. Evans was about three hundred miles east of Williamson Town, the site of the first landing on the Moon. Evans was due back at Williamson Town at about sunset, that is, in about sixteen days. 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. When the meteor pierced the turbine, the water in the condenser began to boil. 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. It was one day's supply if used wastefully. They might have appeared to waver slightly, if they were behind outflung corona flares. He moved to the round window, screening his eyes from the light, and adjusted the polaroid shade to maximum density. This was to allow the air-conditioning system to function properly, and to prevent air loss in case of the highly improbable meteor damage. McIlroy had no illusions about his ability to lead men.
 If he is to discover a new water source, he must utilize his low, existing source to find it
 He has a limited amount of time until the next meteor shower hits and permanently destroys his equipment  In submitting a claim to the lava mine, he will attract violence from those desperate for water  By entering into an unknown cave, he is possibly exposing himself to lava, which has the capacity to melt his space suit  If he is to discover a new water source, he must utilize his low, existing source to find it