Mars 3

Launch date: 28 May 1971
Nation: USSR
Outcome: success

Mars 3 descent module was released at 09:14 UT on December 2, 1971, 4 hours 35 minutes before reaching Mars. The descent module entered the Martian atmosphere at roughly 5.7 km/s. Through aerodynamic braking, parachutes, and retrorockets, the lander achieved a soft landing at 45° S, 158° W and began operations.

After 14.5 seconds, at 13:52:25, transmission on both data channels stopped for unknown reasons and no further signals were received at Earth from the martian surface. It is not known whether the fault originated with the lander or the communications relay on the orbiter.

Note: in according to other versions of the facts, the phototelevision cameras on Mars-3 were functional after the dust storm which caused the black-out. At least four photographic surveys have been reported (Dec 12, 14, Feb 28, Mar 12). Images were returned by pulse-code modulation over the decimeter-band telemetry channel, after the centimeter-band pulse-position modulation system failed.