Lander spacecraft system

The Mars 3 descent module was mounted on the bus/orbiter opposite the propulsion system. It consisted of a spherical 1.2 m diameter landing capsule, a 2.9 m diameter conical aerodynamic braking shield, a parachute system and retro-rockets.

The entire descent module had a fueled mass of 1210 kg, the spherical landing capsule accounted for 358 kg of this. An automatic control system consisting of gas micro-engines and pressurized nitrogen containers provided attitude control. Four solid-fuel motors were mounted to the outer edge of the cone to control pitch and yaw.

The main and auxiliary parachutes, the engine to initiate the landing, and the radar altimeter were mounted on the top section of the lander. Foam was used to absorb shock within the descent module. The landing capsule had four triangular petals which would open after landing, righting the spacecraft and exposing the instrumentation.

The lander was equipped with two television cameras with a 360 degree view of the surface as well as a mass spectrometer to study atmospheric composition; temperature, pressure, and wind sensors; and devices to measure mechanical and chemical properties of the surface, including a mechanical scoop to search for organic materials and signs of life. It also contained a pennant with the Soviet coat of arms.

Four aerials protruded from the top of the sphere to provide communications with the orbiter via an onboard radio system. The equipment was powered by batteries which were charged by the orbiter prior to separation. Temperature control was maintained through thermal insulation and a system of radiators. The landing capsule was sterilized before launch to prevent contamination of the martian environment.

PrOP-M rover

Main article: PrOP-M

Rendering of the PrOP-M

Mars 3 lander had a small 4.5 kg Mars rover on board, which would move across the surface on skis while connected to the lander with a 15-meter umbilical. Two small metal rods were used for autonomous obstacle avoidance, as radio signals from Earth would take too long to drive the rovers using remote control. The rover carried a dynamic penetrometer and a radiation densitometer.^[4]

The main PrOP-M frame was a square box with a small protrusion at the center. The frame was supported on two wide flat skis, one extending down from each side elevating the frame slightly above the surface.

The rover was planned to be placed on the surface after landing by a manipulator arm and to move in the field of view of the television cameras and stop to make measurements every 1.5 metres. The traces of movement in the Martian soil would also be recorded to determine material properties.

Due to communication loss it is unknown whether the rover was deployed.

Entry, descent, landing, transmission, and failure

Mars 3's descent module was released at 09:14 UT on December 2, 1971, 4 hours 35 minutes before reaching Mars.^[6] 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 202°E / 45°S 202°E / -45; 202^[3] and began operations.

The lander began transmitting to the Mars 3 orbiter 90 seconds after landing.^[6] After 20 seconds, transmission stopped for unknown reasons.^[6] It is not known whether the fault originated with the lander or the communications relay on the orbiter. The cause of the failure may have been related to the extremely powerful dust storm taking place at the time which may have induced a coronal discharge, damaging the communications system. The dust storm would also explain the poor image lighting.^[4]

A partial image (70 lines) was transmitted. According to V. G. Perminov, the lead designer for Mars and Venus spacecraft at the Lavochkin design bureau during the early days of Mars exploration, the image was "a gray background with no details".^[4]

• 
  A cut-away view of the Mars 3 Lander at the NPO Lavochkin Museum.
• 
  The only result received from the camera on Mars 3 lander.

Possible images of lander on Mars

On April 11, 2013, NASA announced that the Mars Reconnaissance Orbiter (MRO) may have imaged the Mars 3 lander hardware on the surface of Mars. The HiRISE camera on the MRO took images of what may be the parachute, retrorockets, heat shield and lander.^[3] This discovery was made by amateur space enthusiasts looking through publicly available archived images.^[7][8]

Candidate hardware for 1971 Soviet Mars 3 lander. The predicted landing site was at latitude 45 degrees south, longitude 202 degrees east, in Ptolemaeus Crater (images: HiRISE, MRO - November 2007/left & 10 March 2013/right).^[3]