Lunokhod (Russian for "Moon walker") 1 and 2 were a pair of robotic lunar rovers landed on the Moon by the Soviet Union. They were in operation conterminously with the Zond series of flyby missions. The Lunokhod missions were primarily designed to explore the surface and return pictures. This complemented the Luna series of missions that were intended to be sample return missions and orbiters. They were designed by NPO Lavochkin.
Lunokhod's original primary mission was the survey of sites for later manned landings and lunar bases. Also, it was intended that the spacecraft would provide a radio beacon for precision landings of manned spacecraft. Originally, the vehicle was designed to be used by a single cosmonaut between primary and back-up LK Landers in case of failure. Instead, it was used for remote exploration of the lunar surface after the successful Apollo manned lunar landings.
Lunokhod 1 (Луноход, moon walker in Russian) was the first of two unmanned lunar rovers landed on the Moon by the Soviet Union as part of its Lunokhod program. The spacecraft which carried Lunokhod 1 was named Luna 17. Lunokhod was the first roving remote-controlled robot to land on another world.
Luna 17 was launched on 1970-11-10 at 14:44:01 UTC. After reaching Earth parking orbit, the final stage of Luna 17's launching rocket fired to place it into a trajectory towards the Moon (1970-11-10 at 14:54 UTC). After two course correction manoeuvres (on November 12 and 14) it entered lunar orbit on 1970-11-15 at 22:00 UTC.
The spacecraft soft-landed on the Moon in the Sea of Rains on November 17 at 03:47 UTC. The lander had dual ramps from which the payload, Lunokhod 1, could descend to the lunar surface. At 06:28 UT the rover moved onto the moon's surface.
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 energy source.
Lunokhod 1 was a lunar vehicle formed of a tub-like compartment with a large convex lid on eight independently powered wheels. Its length was 2.3 metres. Lunokhod 1 was equipped with a cone-shaped antenna, a highly directional helical antenna, four television cameras, and special extendable devices to impact the lunar soil for density measurements and mechanical property tests.
An X-ray spectrometer, an X-ray telescope, cosmic ray detectors, and a laser device were also included. The vehicle was powered by batteries which were recharged during the lunar day by a solar cell array mounted on the underside of the lid. During the lunar nights, the lid was closed and a polonium-210 heat source kept the internal components at operating temperature.
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 (4 ft 11 in) wide and had 8 wheels each with an independent suspension, motor and brake. The rover had two speeds, ~1 km/h and ~2 km/h (0.6 mph and 1.2 mph).
- Cameras (two TV & four panoramic telephotometers)
- RIFMA X-ray fluorescence spectrometer
- RT-1 X-ray telescope
- PrOP odometer/penetrometer
- RV-2N radiation detector
- TL laser retroreflector
The SL-12/D-1-e launcher put the spacecraft into Earth parking orbit in 1973-01-08, followed by translunar injection. On 1973-01-12, Luna 21 was braked into a 90 by 100 km (approx. 56 by 62 mile) orbit about the Moon.
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.
Landing occurred on January 15, 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.
Lunokhod 2 was equipped with three television 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 (not frames per second). These images were used by a five-man team of controllers on Earth who sent driving commands to the rover in real time. There were 4 panoramic cameras mounted on the rover.
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 radioactive heat source was used to keep the rover warm during the long lunar nights.
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.
- Cameras (three TV & four panoramic telephotometers)
- RIFMA-M X-ray fluorescence spectrometer
- X-ray telescope
- PROP odometer/penetrometer
- RV-2N-LS radiation detector
- TL laser retroreflector
- AF-3L UV/visible astrophotometer
- SG-70A magnetometer
- Rubin 1 photodetector
Lunokhod 3 was built, but never flown to the Moon. It remains at the NPO Lavochkin museum.
During its 322 Earth days of operations, Lunokhod 1 traveled 10.5 km and returned more than 20,000 TV images and 206 high-resolution panoramas. In addition, it performed twenty-five soil analyses with its RIFMA x-ray fluorescence spectrometer and used its penetrometer at 500 different locations.
Lunokhod 2 operated for about 4 months, covered 37 km (23 miles) 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.
Present locations and ownership
The final location of Lunokhod 1 is uncertain by a few kilometers since lunar laser ranging experiments have failed to detect a return signal from it since the 1970s.<ref>http://www.space.com/scienceastronomy/060327_mystery_monday.html</ref> Notwithstanding, Lunokhod 1 and the Luna 17 lander were sold by auction for $68500 in 1993 at Sotheby's in New York. The auction catalog listing described the spacecraft as "resting on the surface of the moon".<ref>http://www.maineantiquedigest.com/articles/jun03/spac0603.htm</ref>
Lunokhod 2 continues to be detected by lunar laser ranging experiments and its position is known to sub-meter accuracy. Computer gaming entrepreneur and astronaut's son Richard Garriott (also known as Lord British) stated in a 2001 interview with Computer Games Magazine's Cindy Yans that:
I purchased Lunakod 21 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!<ref>http://demiurg.net/games/lb/</ref>
It is possible, but not certain, that by "Lunakod 21" he meant Luna 21 / Lunokhod 2, which would then have been a separate purchase from the auction of Lunokhod 1 / Luna 17.
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- Vinogradov, A. P. (ed.), (1971). Peredvizhnaya Laboratoriya na Lune Lunokhod-1. Tom 1. Moscow, Nauka.
- Barsukov, V. L. (ed.), (1978) Peredvizhnaya Laboratoriya na Lune Lunokhod-1. Tom 2. Moscow, Nauka.
- Lunar Lost & Found: The Search for Old Spacecraft by Leonard David, Space.com 2006 March 27.
- Maine Antiques Digest, June 2003
- Cindy Yans' 2001 interview with Richard Garriott
- The Other Moon Landings, by Andy Chaikin, Smithsonian Air & Space magazine February/March 2004 (Table of Contents only)
- Lunar and Planetary Department Moscow University
- Exploring the Moon (1969-1976) - a diary of significant events in Soviet lunar exploration, including those associated with the Lunokhod programme
- Don P. Mitchell's catalog of Soviet Moon Images including many from the Lunokhod programme
- Lunakhod article at Lunarpedia