On December 2, 1971 Soviet automatic interplanetary station (AIS) Mars-3 has become the world's first spacecraft which made a soft landing on Mars.

Launch vehicle Proton carrying AIS was launched from Baikonur cosmodrome on May 28, 1971. The flight duration was more than six months. During this period 159 radio communication sessions were held, a large amount of scientific information on the interplanetary space and Mars surroundings was obtained.

The AIS descent capsule landed in the southern hemisphere of Mars, and then video signal transfer from the planet surface began. The signal was received by the orbital station receivers and transmitted to Earth during communication passes on December 2-5.

Mars-3 AIS consisted of the orbital compartment and descent vehicle. The orbital compartment included a jet thruster, solar array, antenna-feeder devices and thermal control system radiators. The descent vehicle was equipped with an automatic Mars station, systems and devices, which provided the vehicle separation from the space station, its transition to the planet approach path, deceleration, reentry and soft landing on the surface of Mars. The descent module was also equipped with the hardware to measure wind speed, temperature and atmospheric pressure, provide mass-spectrometer measurements of the composition of atmosphere, physical and mechanical properties and chemical composition of the surface layer, as well as to obtain a panoramic picture using television cameras. The total mass of Mars-3 was 4650 kg. A comprehensive program of Mars investigations using AIS kept going for more than eight months.