Phobos program

The Phobos (Фобос, Fobos, Φόβος) program was an unmanned space mission consisting of two probes launched by the Soviet Union to study Mars and its moons Phobos and Deimos. Phobos 1 was launched on 7 July 1988, and Phobos 2 on 12 July 1988, each aboard a Proton-K rocket. Phobos 1 suffered a terminal failure en route to Mars. Phobos 2 attained Mars orbit, but contact was lost before the final phase, prior to deployment of the planned Phobos landers. Phobos 1 and 2 were of a new spacecraft design, succeeding the 4MV type used in the Venera planetary missions of 1975–1985, and the 5VK design last used during the Vega 1 and Vega 2 missions to Comet Halley. They each had a mass of 2600 kg (6220 kg with orbital insertion hardware attached). The program featured cooperation from 14 other nations, including Sweden, Switzerland, Austria, France, West Germany, and the United States (which contributed the use of its NASA Deep Space Network for tracking the twin spacecraft). The objectives of the Phobos missions were to: conduct studies of the interplanetary environment; perform observations of the Sun; characterize the plasma environment in the Martian vicinity; conduct surface and atmospheric studies of Mars; and, study the surface composition of the Martian satellite Phobos. The main section of the spacecraft consisted of a pressurized toroidal electronics section, surrounding a modular cylindrical experiment section. Below these were mounted four spherical tanks (the Fregat stage) containing hydrazine for attitude control and, after the main propulsion module was to be jettisoned, orbit adjustment. A total of 28 thrusters (twenty-four 50 N thrusters and four 10 N thrusters) were mounted on the spherical tanks, with additional thrusters mounted on the spacecraft body and solar panels. Attitude was maintained through the use of a three-axis control system, with pointing maintained with Sun and star sensors. Phobos 1 Phobos 1 operated nominally until, a few weeks into the cruise to Mars, an expected communications session on September 2, 1988, failed to occur.