 What is the most precious commodity on the moon?
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. Once he followed a stampede to Yellow Crater, where he thought for a while that he had a fortune in chromium. Four days reserve—plus one is five—plus sixteen days normal supply equals twenty-one days to live. Morning to him had no meaning at all, but he thought in the strictest sense that it would be morning on the Moon for another week. It was used mostly, from sun-up to sun-down, to supplement the nuclear power plant.
 Water
 Water  Oxygen  Natural gas  Chromite ore