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
Phobos 2 to approach within of Phobos' surface and release two landers, one a mobile , the other a stationary platform, contact with "Phobos 2" was lost. The mission ended when the spacecraft signal failed to be successfully reacquired on 27 March 1989. The cause of the failure was determined to be a malfunction of the on-board computer. The "Phobos 2" infrared spectrometer (ISM) obtained 45000 spectra in the near infrared (from ) in the equatorial areas of Mars, with a spatial resolution ranging from , and 400 spectra of Phobos at 700 m resolution. These observations made it possible to retrieve