Fobos 1 (cruise configuration)
Fobos 2 (orbital configuration)
Fobos 2 Hopper
Fobos 1 and 2 were nearly identical spacecraft to explore the martian moon Phobos. The mission included co-operation from 14 other nations including Sweden, Switzerland, Austria, France, West Germany, and the United States (who contributed the use of its Deep Space Network for tracking the twin spacecraft).
The objectives of the Fobos 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 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.
Following instruments were on board of the probes:
Both probes carried a small solar-powered Phobos surface station called DAS, which carried panoramic stereo TV system, seismometer, magnetometer, X-ray fluorescence spectrometer, alpha particle scattering device and a penetrator.
Fobos-2 carried a unique lander called Hopper to make surface measurements on different locations on the surface of Phobos. This battery-powered lander would have had only a short lifetime. It featured spring powered "legs", which enabled the probe to align it self correctly after landing and perform up to 10 hops of about 20 m on the surface. It featured following instruments:
Fobos 1 operated nominally until an expected communications session on 2 September 1989 failed to occur. The failure of controllers to regain contact with the spacecraft was traced to an error in the software uploaded on 29/30 August which had deactivated the attitude thrusters. This resulted in a loss of lock on the Sun, resulting in the spacecraft orienting the solar arrays away from the Sun, thus depleting the batteries.
Fobos 2 operated nominally throughout its cruise and Mars orbital insertion phases, gathering data on the Sun, interplanetary medium, Mars, and Phobos. Shortly before the final phase of the mission, during which the spacecraft was to approach within 50 m of Phobos' surface and release two landers, one a mobile `hopper', the other a stationary platform, contact with Fobos 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.
|Type / Application:||Mars orbiter, 1 or 2 Phobos lander|
|Power:||2 deployable solar arrays, batteries|
|Fobos 1||1988-058A||07.07.1988||Ba LC-200/39||Proton-K Blok-D-2|
|Fobos 2||1988-059A||12.07.1988||Ba LC-200/40||Proton-K Blok-D-2|
|Fobos 3||-||not launched|