Promethei Terra is a large Martian region covering 3300 km at its broadest extent. It lies to the east of the massive Hellas basin. Like much of the southern part of the planet it is a heavily cratered, highland region. Promethei Terra was named for a classic albedo feature of Mars, with the original name derived from that of the Greek god Prometheus. Promethei Terra lies mostly in the Hellas quadrangle of Mars.
One very important feature common in Promethei Terra are piles of material surrounding cliffs. These materials are called lobate debris aprons (LDA's). Recently, research with the Shallow Radar on the Mars Reconnaissance Orbiter has provided strong evidence that the LDA's are glaciers that are covered with a thin layer of rocks. Large amounts of water ice are believed to be in the LDA's. Available evidence strongly suggests this area accumulated snow in the past. When the tilt (obliquity) of Mars increases the southern ice cap releases large amounts of water vapor. Climate models predict that when this occurs water vapor condenses and falls where LDAs are located. The tilt of the earth changes little because our relatively large moon keeps it stable. The two tiny Martian moons do not stabilize its planet, so the rotational axis of Mars undergoes large variations.  Lobate debris aprons may be a major source of water for future Mars colonists. Their major advantage over other sources of Martian water are that they can easily mapped from orbit and they are closer to the equator where manned missions are more likely to land.