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Lunokhod series Soviet Moon exploration robot vehicle
|Launch date||January 11, 1973 at 06:55:38 UTC|
|Mission duration||ended on June 4, 1973|
|Orbital insertion date||Landed on January 15, 1973|
|Mass||840 kg (rover)|
The Luna 21 spacecraft landed on the Moon and deployed the second Soviet lunar rover (Lunokhod 2) in January 1973. 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 the soil mechanics of the lunar surface material.
Lunokhod 2 rover and subsystems 
The rover stood 135 cm (4 ft 5 in) high and had a mass of 840 kg (1,850 lb). It was about 170 cm (5 ft 7 in) long and 160 cm (5 ft 3 in) wide and had eight wheels each with an independent suspension, electric motor and brake. The rover had two speeds, ~1 km/h and ~2 km/h (0.6 mph and 1.2 mph). Lunokhod 2 was equipped with three television cameras, one mounted high on the rover for navigation, which could return high resolution images at different frame 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 radioisotope heater unit was used to keep the rover warm during the long lunar nights. There were four panoramic cameras mounted on the rover. Scientific instruments included a soil mechanics tester, solar X-ray experiment, an astrophotometer to measure visible and ultraviolet light levels, a magnetometer deployed in front of the rover on the end of a 2.5 m (8 ft 2 in) boom, a radiometer, a photodetector (Rubin-1) for laser detection experiments, and a French-supplied laser corner reflector. The lander carried a bas relief of Vladimir Lenin and the Soviet coat of arms. The lander and rover together massed 1814 kg.
Mission profile 
The Proton-K/D launcher put the spacecraft into Earth parking orbit followed by translunar injection. On January 12, 1973 Luna 21 was braked into a 90 by 100 km (56 by 62 mile) lunar orbit. On January 13 and January 14, the perilune was lowered to 16 km (9.9 mi) altitude.
Landing and surface operations 
On January 15 after 40 orbits, the braking rocket was fired at 16 km (9.9 mi) altitude, and the craft began to de-orbit. At an altitude of 750 m (2,460 ft) the main thrusters began firing, slowing the fall until a height of 22 m (72 ft) was reached. At this point the main thrusters shut down and the secondary thrusters ignited, slowing the fall until the lander was 1.5 m (5 ft) above the surface, where the engine was switched off. Landing occurred at 23:35 UT in Le Monnier crater at 25.85 degrees N, 30.45 degrees E.
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 January 16 and took pictures of the Luna 21 lander and landing site, driving for 30 metres. After a period of charging up its batteries, it took more pictures of the site and the lander, and then set off to explore the moon.
The rover would run during the lunar day, stopping occasionally to recharge its batteries with the solar panels. At night the rover hibernated until the next sunrise, heated by the radioactive source.
- January 18, 1973 to January 24, 1973: The rover drives 1,260 metres
- February 8, 1973 to February 23, 1973: The rover drives 9,086 metres further
- March 11, 1973 to March 23, 1973: The rover drives 16,533 metres further
- April 9, 1973 to April 22, 1973: The rover drives 8,600 metres further
- May 8, 1973 to June 3, 1973: The rover drives 880 metres further
End of mission 
On June 4, 1973 it was announced that the program was completed, leading to speculation that the vehicle probably failed in mid-May or could not be revived after the lunar night of May–June.
More recently, Alexander Basilevsky related an account where on May 9, 1973, the rover's open lid touched a crater wall and became covered with dust. When the lid was closed, this dust (a very good insulator) was dumped on to the radiators. The following day, May 10, controllers saw the internal temperature of the Lunokhod climb as it was unable to cool itself, eventually rendering the rover inoperable. On May 11, 1973 signal from the rover was lost.
Lunokhod 2 operated for about 4 months, covered slightly more than 37 km (23 mi) 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.
Even by May 2013, its journey remained the longest any robotic rover, or any vehicle, that had ever driven on another celestial body; the crewed Apollo 17 Lunar Roving Vehicle travelled 35.75 km, and the still extant robotic Opportunity Rover had travelled 35.76 km on Mars.
Current status 
Lunokhod 2 continues to be detected by lunar laser ranging experiments and its position is known to sub-meter accuracy. On March 17, 2010 Phil Stooke, a professor at the University of Western Ontario announced that he had located Lunokhod 2's final resting place in photographs made by the NASA Lunar Reconnaissance Orbiter (LRO). However, the reported identification was incorrect and the LRO LROC team identified the correct location of the rover. The spacecraft was photographed by the LRO in March 2012. Excellent Lunokhod 2 images from LROC published by Mark Robinson on SESE site of ASU.
Present ownership 
Ownership of Lunokhod 2 and the Luna 21 lander was sold by the Lavochkin Association for $68,500 in December 1993 at a Sotheby's auction in New York. (The catalog incorrectly lists lot 68A as Luna 17/Lunokhod 1).
- I purchased Lunakod 21 [sic] from the Russians. I am now the world's only private owner of an object on a foreign celestial body. Though there are international treaties that say, no government shall lay claim to geography off planet earth, I am not a government. Summarily, I claim the moon in the name of Lord British!
See also 
|Wikimedia Commons has media related to: Lunokhod program|
- Mulholland, J. D.; Shelus, P. J.; Silverburg, E. C. "Laser observations of the moon: Normal points for 1973". NASA. NTRS. Retrieved Jan 1, 1975.
- "The Other Moon Landings", by Andrew Chaikin, (Air & Space Magazine, February/March 2004, pages 30-37
- Stooke, Phil (2010-03-17). "Lunokhod 2 found! .... and guess who found it?". unmannedspaceflight.com. Retrieved 18 March 2010.
- "Lunar Geophysics, Geodesy, and Dynamics". ilrs.gsfc.nasa.gov. Retrieved 2008-02-06.
- "Russian Lunar Rover Found: 37-Year-Old Space Mystery Solved". Science Daily. Retrieved 2010-03-17.
- David, Leonard (2010-03-18). "NASA Lunar Orbiter Spots Old Soviet Moon Landers".
- Chang, Kenneth (March 20, 2010). "After 17 Years, a Glimpse of a Lunar Purchase". New York Times. Retrieved 2010-04-01. "Richard A. Garriott has finally seen the item he bought 17 years ago for $68,500."
- Page, Lewis (March 16, 2012). "New NASA snap of game developer's electric cart FOUND ON MOON: Probe in low pass over Garriott's radioactive tub-rover". The Register. Retrieved March 16, 2012.
- Lunokhod 2 Revisited
- The Bloc on the Block (by Jeffrey Kluger): Discover magazine, April 1994
- Sotheby's Catalogue - Russian Space History, Addendum, Lot 68A, December 11, 1993
- Lord British, we hardly knew ye
- The Astronaut's Son's Secret Sputnik, CollectSPACE October 2007
- Are We Alone (podcast interview with SETI Institute Director Seth Shostak), December 10, 2007
- Zarya - Lunokhod 2 chronology
- Don P. Mitchell's catalog of Soviet Moon Images including many from Lunokhod 2
- Lunokhod 2 information and VRML models at the Virtual Space Museum
- Lunokhod 2 panoramic images
- Lunokhod 2 in space museum - 360 degree panoramic image