Named after the Town in New South Wales, Australia.
Cooma is a town in the south of New South Wales, Australia. It is located 114 kilometres south of the national capital, Canberra, via the Monaro Highway. It is also on the Snowy Mountains Highway, connecting Bega with the Riverina. The town has a population of 6,301. (wikipedia entry)
A crater is a circular depression likely created by an impact event. On Mars large craters are named after deceased scientists, writers and others who have contributed to the lore of Mars. Small creaters (less than 60km) are named after small towns and villages.