Investigations of the planet Venus and Halley's Comet. The APV-V plasma antenna did not deploy until the first mid-course correction burn. Deployed lander and balloon at Venus on June 19 1985. Rendezvoused with comet Halley on March 6, 1986. Fitted with scientific apparatus and equipment built in the USSR, Austria, Bulgaria, Hungary, German Democratic Republic, Poland, France, Federal Republic of Germany and C zechoslovakia.

Investigations of the planet Venus and Halley's Comet. The APV-V plasma antenna did not deploy until the first mid-course correction burn. Deployed lander and balloon at Venus on June 14, 1985. The surface experiments of the lander failed to send back data because they were inadvertently switched on at an altitude of 20 km. Apparently high winds activated a G-force sensor that was to automatically switch on the surface package after the jolt of touchdown. The bus continued in heliocentric orbit and rendezvoused with comet Halley on March 9, 1986. The images of the comet were nearly lost when a television sensor failed shortly before the flyby. A back-up sensor was activated just in time. Fitted with scientific apparatus and equipment built in the USSR, Austria, Bulgaria, Hungary, German Democratic Republic, Poland, France, Federal Republic of Germany and C zechoslovakia.

Second of two missions to Mars' moon Phobos; carried 2 landers; planned to enter Mars orbit. Phobos 1 operated nominally until an expected communications session on 2 September 1988 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. Left in solar Orbit (Heliocentric).

First of two Mars missions to Mars' moon Phobos; carried two landers; entered Mars orbit 1/29/89; failed 3/27/89; extremely limited science data. Phobos 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 Phobos 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.

Phobos 2 operated nominally throughout its cruise and entered Mars orbit on January 29, 1989. Contact with the vehicle was lost on March 27, 1989 shortly before the final phase of the mission during which the spacecraft was to approach within 50 meters of Phobos' surface and release its two landers. The cause of the failure was determined to be a malfunction of the on-board computer.

The Mars 96 spacecraft was launched into Earth orbit, but failed to achieve insertion into Mars cruise trajectory and re-entered the Earth's atmosphere at about 00:45 to 01:30 GMT on 17 November 1996 and crashed within a presumed 320 km by 80 km area which includes parts of the Pacific Ocean, Chile, and Bolivia. The Russian Mars 96 mission was designed to send an orbiter, two small autonomous stations, and two surface penetrators to Mars.

Failed soil-return mission to Martian moon Phobos. The main propulsion system, which was to have boosted the probe out of earth parking orbit to trans-Mars insertion, failed to ignite. Attempts to communicate with the spacecraft partially succeeded but it could not be commanded to conduct an engine burn at a later opportunity. Destroyed on reentry into the earth's atmosphere.