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
Nu Earth Souther forces arrive to recapture the trenches. Nu Earth Nu-Earth is the name of a fictional planet near two suns and a wormhole that is the main setting for the Rogue Trooper fictional universe. Due to its strategic importance the Southers and the Norts are fighting over the planet. This perpetual war has seen the use of just about every weapon of mass destruction, which made the planet's atmosphere toxic. Most life forms became extinct or mutated, and all inhabitants must wear protective chem-suits at all times. Because of this the Souther scientists were instructed to start the G.I. program