Rare Earth hypothesis the atmosphere is not stripped over time by solar winds. A terrestrial planet of the right size is needed to retain an atmosphere, like Earth and Venus. On Earth, once the giant impact of Theia thinned Earth's atmosphere, other events were needed to make the atmosphere capable of sustaining life. The Late Heavy Bombardment reseeded Earth with water lost after the impact of Theia. The development of an ozone layer formed protection from ultraviolet (UV) sunlight. Nitrogen and carbon dioxide are needed in a correct ratio for life to form. Lightning is needed for nitrogen fixation. The carbon dioxide gas
Gas-s-s-s ahead, write something, just keep the title."" "Gas-s-s-s" was an idea of Corman's, about a world where everybody over thirty had died. Corman later said "my first thought was to do a science fiction film with allegorical overtones." Armitage remembers the concept just being "a sentence, and that's what we went with ... He let you make it your own, and I did." Corman said that although "there was some good work in" Armitage's first draft, "the points I was trying to make in the script either did not come through or came through too obviously different parts, and it