Moons of Mars Sun's angular diameter as seen from Mars, by contrast, is about 21'. Thus there are no total solar eclipses on Mars, as the moons are far too small to completely cover the Sun. On the other hand, total lunar eclipses of Phobos are very common, happening almost every night. The motions of Phobos and Deimos would appear very different from that of our own Moon. Speedy Phobos rises in the west, sets in the east, and rises again in just eleven hours, while Deimos, being only just outside synchronous orbit, rises as expected in the east but very slowly. Despite
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