Mars lake was discovered using the MARSIS radar on board the "Mars Express" orbiter, and the profiles were collected between May 2012 and December 2015. The lake is centered at 193°E, 81°S, a flat area that does not exhibit any peculiar topographic characteristics. It is mostly surrounded by higher ground except on its eastern side, where there is a depression. Mars has two relatively small (compared to Earth's) natural moons, Phobos (about in diameter) and Deimos (about in diameter), which orbit close to the planet. Asteroid capture is a long-favored theory, but their origin remains uncertain. Both satellites were discovered in
Colonization of Mars of life forms, including humans, to survive unaided on Mars's surface. Some ideas of possible technologies that may be able to contribute to the actual terraforming of Mars have been conjectured, but none would be able to bring the entire planet into the Earth-like science fiction habitat pictured. Mars lacks enough gravity to hold on to any kind of substantial atmosphere, which in turn means that the planet will remain cold and cloudless, and the extremely scarce surface water frozen. Mars has no global magnetosphere as Earth does. Combined with a thin atmosphere, this permits a significant amount of ionizing