PHOBOS - Gains from a loss

Two Phobos probes launched by the USSR in 1988 failed before their missions were completed. However, Phobos 2 did last long enough to complete the first two phases of its mission: studying the sun and the interplanetary medium on the way out, and Mars from a distance while in orbit around the planet. Returned data have been helpful in studying why water has disappeared from Mar's surface. The data indicate that solar wind may be the cause. Instruments measured the energy and direction of ions near Mars, indicating that the planet is currently losing about 1 kg/sec of its intact atmosphere to the impact of the solar wind. Another result from Mars was the detection of extremely fine particles, probably a mixture of water-ice and dust, high in the atmosphere. The reasons for the failure of the two spacecraft and the lessons that may be obtained for future missions are discussed.