History of Earth the third atmosphere, rich in oxygen, emerged when bacteria began to produce oxygen about 2.8 Ga. In early models for the formation of the atmosphere and ocean, the second atmosphere was formed by outgassing of volatiles from the Earth's interior. Now it is considered likely that many of the volatiles were delivered during accretion by a process known as "impact degassing" in which incoming bodies vaporize on impact. The ocean and atmosphere would, therefore, have started to form even as the Earth formed. The new atmosphere probably contained water vapor, carbon dioxide, nitrogen, and smaller amounts of other gases. Planetesimals
Gas turbine gas-turbine powered ship was the U.S. Coast Guard's , a cutter commissioned in 1961 that was powered by two turbines utilizing controllable-pitch propellers. The larger High Endurance Cutters, was the first class of larger cutters to utilize gas turbines, the first of which () was commissioned in 1967. Since then, they have powered the U.S. Navy's s, and s, and guided missile cruisers. , a modified , is to be the Navy's first amphibious assault ship powered by gas turbines. The marine gas turbine operates in a more corrosive atmosphere due to the presence of sea salt in air and