Nine days after the launch of Mars Global Surveyor, Russia launched Mars 96, aka "Mars 8." This was an extremely ambitious mission, and was the heaviest interplanetary spacecraft ever launched. Intended subjects of investigation included the Martian surface and atmosphere, the inner structure of the planet, solar plasma studies (especially of the sun's and Mars' magnetic fields), and astrophysical studies, including the study of cosmic gamma ray bursts. Mars 96 had several components, including an orbiter based on the Phobos orbiter design, two surface stations that were to land in separate locations on the northern hemisphere of Mars, and two penetrators, which would separate into two pieces upon impact. Both pieces had scientific equipment in them. The forebody was to penetrate up to 5-6 meters beneath the surface, while the afterbody would remain near the surface and transmit back the data.
Mars 96 lifted off on November 16, 1996 on a Proton 8K82K/11S824F rocket. This is a four stage rocket in a configuration that had flown only twice before, launching the two Phobos spacecraft. The rocket performed properly up to parking orbit. However, the planned second burn of the Block D-2 fourth stage shut down prematurely after a 20 second burn. Mars 96 and its Fregat module then automatically separated from the Blok D-2. The latter seems to have fired (as planned earlier), placing Mars 96 into an orbit that deposited the spacecraft into the Earth's atmosphere. Mars 96 burned up, falling somewhere in the vicinity of Chile, Bolivia or the Pacific Ocean off the Chilean or Bolivian coast. The Block D-2 re-entered on a later orbit.
Mars 96 is, to date, the last Mars mission undertaken by Russia/Soviet Union. The Soviet Union tried to send a total of 18 missions to Mars and the Russian Federation, one. Of all nineteen missions, none could be considered a complete success and only five a partial success. Even of those five, it is difficult to say which was the most successful mission.
The above image is a NASA computer-generated model of the Mars 96 (Mars 8) Orbiter.