Phobos program

The Phobos (Russian: Фобос, Fobos, Greek: 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 a planned Phobos lander. Phobos 1 and 2 were of a new spacecraft design, succeeding the type used in the Venera planetary missions of 1975–1985, 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:

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.

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