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Luna 21/Lunokhod 2



The Luna 21 spacecraft landed on the Moon and deployed the second Soviet lunar rover (Lunokhod 2). The primary objectives of the mission were to collect images of the lunar surface, examine ambient light levels to determine the feasibility of astronomical observations from the Moon, perform laser ranging experiments from Earth, observe solar X-rays, measure local magnetic fields, and study mechanical properties of the lunar surface material.

Lunokhod 2 Rover and Subsystems

The rover stood 135 cm high and had a mass of 840 kg. It was about 170 cm long and 160 cm wide and had 8 wheels, each with an independent suspension, motor and brake. The rover had two speeds, ~1 km/hr and ~2 km/hr. Lunokhod 2 was equipped with three TV cameras, one mounted high on the rover for navigation, which could return high resolution images at different rates (3.2, 5.7, 10.9 or 21.1 seconds per frame). These images were used by a five-man team of controllers on Earth who sent driving commands to the rover in real time. Power was supplied by a solar panel on the inside of a round hinged lid which covered the instrument bay, which would charge the batteries when opened. A polonium-210 isotopic heat source was used to keep the rover warm during the lunar nights. There were 4 panoramic cameras mounted on the rover. Scientific instruments included a soil mechanics tester, solar X-ray experiment, an astrophotometer to measure visible and UV light levels, a magnetometer deployed in front of the rover on the end of a 2.5 m boom, a radiometer, a photodetector (Rubin-1) for laser detection experiments, and a French-supplied laser corner-reflector. The lander and rover together weighed 1814 kg.

Mission Profile

The SL-12/D-1-e launcher put the spacecraft into Earth parking orbit followed by translunar injection. On 12 January 1973, Luna 21 was braked into a 90 x 100 km orbit about the Moon. On 13 and 14 January, the perilune was lowered to 16 km altitude. On 15 January after 40 orbits, the braking rocket was fired at 16 km altitude, and the craft went into free fall. At an altitude of 750 meters the main thrusters began firing, slowing the fall until a height of 22 meters was reached. At this point the main thrusters shut down and the secondary thrusters ignited, slowing the fall until the lander was 1.5 meters above the surface, where the engine was cut off. Landing occurred at 23:35 UT in LeMonnier crater at 25.9994 degrees N, 30.4076 degrees E. The lander carried a bas relief of Lenin and the Soviet coat-of-arms.

After landing, the Lunokhod 2 took TV images of the surrounding area, then rolled down a ramp to the surface at 01:14 UT on 16 January 1973 and took pictures of the Luna 21 lander and landing site. It stopped and charged batteries until 18 January, took more images of the lander and landing site, and then set out over the Moon. The rover would run during the lunar day, stopping occasionally to recharge its batteries via the solar panels. At night the rover would hibernate until the next sunrise, heated by the radioactive source. Lunokhod 2 operated for about 4 months, covered 37 km of terrain including hilly upland areas and rilles, and sent back 86 panoramic images and over 80,000 TV pictures. Many mechanical tests of the surface, laser ranging measurements, and other experiments were completed during this time.

On 20 April 1973, Lunokhod 2 drove into a small crater. When it drove back out, it did not close the lid. Apparently the lid scraped the wall of the crater and deposited dust on its inner surface. The lid was closed at the end of the lunar day, and the soil in the lid was dumped into the interior of the rover. When the lid was opened for the next lunar day, the dust on the radiator caused the rover to overheat, and on 10 May communications ceased. On June 4 it was announced that the program was completed. The Lunokhod laser retroreflector is still used by Earth-based stations for laser ranging, Lunokhod 2 is located at 25.8323 N, 30.9222 E.

Spacecraft rendered image credit NASA/NSSDCA (public domain)

Alternate Names

  • 06333
  • Luna 21
  • Luna21/Lunokhod2
  • Lunokhod 2

Facts in Brief

Launch Date: 1973-01-08
Launch Vehicle: Proton Booster Plus Upper Stage and Escape Stages
Launch Site: Tyuratam (Baikonur Cosmodrome), U.S.S.R
Mass: 4850 kg

Funding Agency

  • Unknown (U.S.S.R)


  • Planetary Science
  • Space Physics

Additional Information

Questions and comments about this spacecraft can be directed to: Dr. David R. Williams



NameRoleOriginal AffiliationE-mail
Mr. Artem IvankovGeneral ContactLavochkin

Selected References

  • Soviet space programs, 1966-70, Govt. Printing Office, Senate Doc. No. 92-51, Wash., D.C., Dec. 1971.
  • Shelton, W., Soviet space exploration - the first decade, Arthur Barker Ltd., Unnumbered, London, England, 1969.
  • Harvey, B., The new Russian space programme from competition to collaboration, John Wiley and Sons, Chichester, England, 1996.
  • Davies, M. E., and T. R. Colvin, Lunar coordinates in the regions of the Apollo landers, J. Geophys. Res., 105, No. E8, 20277-20280, Aug. 2000.
  • Chaikin, A., The other Moon landings - A Soviet triumph in the shadow of Apollo, Air Space, 30-37, Feb./Mar. 2004.
Image of Lunokhod model

Lunokhod model

Image of Lunokhod mission

Lunokhod mission profile

Images above for illustrative purposes only, not necessarily in the public domain.

Lunokhod and Luna 17/21 Lander models on display at the NPO Lavochkin Museum.
Courtesy of Alexander Chernov and the Virtual Space Museum. All rights reserved.

Luna 17/Lunokhod 1 Information

Other Soviet Lunar Missions
Lunar Science Home Page

Lunokhod rendering

Rendering of Lunokhod Rover (credit NASA/NSSDCA - public domain)

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