Mars mainly phyllosilicates and other minerals known from Mars, point toward an origin of Phobos from material ejected by an impact on Mars that reaccreted in Martian orbit, similar to the prevailing theory for the origin of Earth's moon. Although the VNIR spectra of the moons of Mars resemble those of outer-belt asteroids, the thermal infrared spectra of Phobos are reported to be inconsistent with chondrites of any class. Mars may have moons smaller than in diameter, and a dust ring is predicted to exist between Phobos and Deimos. Dozens of crewless spacecraft, including orbiters, landers, and rovers, have been sent
Phobos 1 into three phases. In stage one the probe would investigate the Sun and interplanetary space while traveling from the Earth to Mars. In stage two the probe would study Mars and Phobos while in orbit around Mars. During the final stage it would approach to within 50 meters of the Phobos surface while conducting several experiments. The Phobos probe carried several scientific experiments. It carried a radar transmitter, X-ray and alpha-backscatter spectrometers, camera, and a laser that could vaporize tiny spots so a reflector could analyze the vapor for atomic masses. The probe also carried a . The hopper would