Editing Lunokhod 2

{{Short description|Second robotic Moon rover (1973)}}
{{Use mdy dates|date=May 2020}}
{{italic title}}
{{Infobox spaceflight
| name               = ''Lunokhod 2''
| image              = Lunokhod-2 model.jpg
| image_caption      = Model of Lunokhod 2 rover
| mission_type       = Lunar rover
| operator           = 
| website            = 
| COSPAR_ID          = 1973-001A
| SATCAT             = 
| mission_duration   = 
| spacecraft_type    = 
| manufacturer       = 
| dry_mass           = {{convert|840|kg|lb}} (rover only)
| launch_mass        = 
| power              = <!-- [[watt]]s -->
| launch_date        = {{start-date|January 11, 1973, 06:55:38|timezone=yes}}&nbsp;UTC
| launch_rocket      = [[Proton-K]]/[[Blok D|D]]
| launch_site        = [[Baikonur Cosmodrome|Baikonur]] [[Baikonur Cosmodrome Site 81|81/23]]
| launch_contractor  = 
| last_contact       = {{end-date|May 11, 1973}}
| orbit_epoch        = 
| orbit_reference    = <!--transfer orbit-->
| orbit_periapsis    = 
| orbit_apoapsis     = 
| orbit_inclination  = 
| apsis              = 
| interplanetary     = {{Infobox spaceflight/IP
   |type                = rover
   |object              = [[Moon|Lunar]]
   |component           = Rover
   |arrival_date        = January 15, 1973
   |location            = 
   |distance            = 
 }}
}}

'''''Lunokhod 2''''' ({{langx|ru|Луноход-2}} ("Moonwalker 2"), also known as '''Аппарат 8ЕЛ № 204''' ("Device 8EL No. 204")) was the second of two [[uncrewed space mission|uncrewed]] lunar [[rover (space exploration)|rover]]s that landed on the [[Moon]] by the [[Soviet Union]] as part of the [[Lunokhod programme]].

The ''[[Luna 21]]'' spacecraft landed on the Moon and deployed the second Soviet [[lunar rover]], ''Lunokhod 2'', in January 1973.<ref name="in-depth">[https://solarsystem.nasa.gov/missions/lunokhod-02/in-depth/ Lunokhod 02] {{Webarchive|url=https://web.archive.org/web/20210418111108/https://solarsystem.nasa.gov/missions/lunokhod-02/in-depth/ |date=April 18, 2021 }}, NASA Solar System Exploration; page updated March 15, 2018. Retrieved May 31, 2018.</ref><ref>NSSDC Catalog, [https://nssdc.gsfc.nasa.gov/nmc/spacecraft/display.action?id=1973-001A Luna 21/Lunokhod 2], version March 21, 2017. Retrieved May 31, 2018.</ref><ref>{{cite journal|author1=Mulholland, J. D. |author2=Shelus, P. J. |author3=Silverburg, E. C. |title=Laser observations of the moon: Normal points for 1973|url=https://ntrs.nasa.gov/search.jsp?R=19750020915|journal=NASA|publisher=NTRS |date=January 1, 1975 |access-date=June 17, 2011}}</ref> The lander and rover together massed 1814&nbsp;kg.  

The primary objectives of the mission were to collect images of the lunar surface, examine [[Available light|ambient light]] levels to determine the feasibility of astronomical observations from the Moon, perform [[laser ranging]] experiments from [[Earth]], observe solar [[X-ray]]s, measure local [[magnetic field]]s, and study the [[soil mechanics]] of the [[lunar soil|lunar surface material]].

== ''Lunokhod 2'' rover and subsystems ==
The rover stood {{convert|135|cm|ftin|abbr=off}} high and had a mass of {{convert|840|kg|lb|abbr=on}}. It was about {{convert|170|cm|ftin|abbr=off}} long and {{convert|160|cm|ftin|abbr=off}} wide and had eight wheels each with an [[independent suspension]], [[electric motor]] and [[brake]]. The rover had two speeds, about {{convert|1|and|2|km/h|mph|abbr=on}}. [[File:LunokhodWheels.jpg|thumb|Detail of Lunokhod's wheels|left]]
''Lunokhod 2'' was equipped with three [[television camera]]s, one mounted high on the rover for navigation, which could return high resolution images at different [[frame rate]]s—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. 

Power was supplied by a [[Photovoltaic module|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 camera]]s mounted on the rover. Scientific instruments included a [[soil mechanics]] tester, solar X-ray experiment, an astro[[photometer]] to measure visible and [[ultraviolet]] light levels, a [[magnetometer]] deployed in front of the rover on the end of a 2.5 [[metre|m]] (8&nbsp;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 [[State Emblem of the Soviet Union]].

== Mission ==
The [[Proton-K]]/[[Blok D|D]] launcher put the spacecraft into Earth [[parking orbit]] followed by [[translunar injection]]. On January 12, 1973, ''Luna 21'' was braked into a {{convert|90|by|100|km|mi|abbr=on}} [[lunar orbit]]. On January 13 and 14, the [[perilune]] was lowered to {{convert|16|km|mi|abbr=on}} altitude.

[[File:Lunokhod-mission.jpg|thumb|'''Scheme of Lunokhod''' mission]]

== Landing and surface operations ==
[[File:Luna 21 lander.png|thumb|Luna 21 lander that delivered the second soviet robotic lunar rover Lunokhod - 2 to the Moon as seen from orbit by Lunar Reconnaissance Orbiter in March, 2010]]
On January 15, 1973, after 40 orbits, the descent of the craft was commenced as the [[braking rocket]] was fired at {{convert|16|km|mi|abbr=on}} altitude, and the craft began to de-orbit. At an altitude of {{convert|750|m|ft|abbr=on}} the main thrusters began firing, slowing the fall until a height of {{convert|22|m|ft|abbr=on}} was reached. At this point the main thrusters shut down and the secondary thrusters ignited, slowing the fall until the lander was {{convert|1.5|m|ft|abbr=on}} above the surface, where the engine was switched off. Landing occurred at 23:35 UT in [[Le Monnier (crater)|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 to 23: The rover drives 9,086 metres further
* March 11 to 23: The rover drives 16,533 metres further
* April 9 to 22: The rover drives 8,600 metres further
* May 8 to June 3: The rover drives 880 metres further
[[File:Lunokhod 2 Luna 21 lunar map.png|thumb|Map of Linokhod 2's path in [[Le Monnier (crater)|Le Monnier crater]] at the eastern rim of [[Mare Serenitatis]]]]

== End of mission ==
[[File:LRO Lunokhod 2.jpg|thumb|Lunar Reconnaissance Orbiter image of Lunokhod 2 and its tracks. The large white arrow indicates the rover, the smaller white arrows indicate the rover's tracks, and the black arrow indicates the crater where it picked up its fatal load of lunar dust.]]

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 in which on May 9, 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 [[radiator]]s. The following day, May 10, controllers saw the internal temperature of ''Lunokhod 2'' climb as it was unable to cool itself, eventually rendering the rover inoperable.<ref name=2004Lunokhod2Airandspace>{{cite news |title=The Other Moon Landings |url=http://www.airspacemag.com/space/the-other-moon-landings-6457729/ <!-- old, dead link: http://www.airspacemag.com/space-exploration/other-moon.html --> |author=Andrew Chaikin |publisher=[[Air & Space/Smithsonian]] |date=March 1, 2004 |access-date=May 25, 2013}}</ref> On May 11, signal from the rover was lost.

== Results ==
[[File:Driving_Distances_on_Mars_and_the_Moon.png|thumb|Driving Distances by rovers on Mars and the Moon as of February 2019.]]
''Lunokhod 2'' operated for about four months, and the original estimate was that it covered {{convert|37|km|mi|abbr=on}} of terrain, including hilly upland areas and rilles, and sent back 86 panoramic images and over 80,000 TV pictures.<ref name=2004Lunokhod2Airandspace/><ref name=2012Lunokhod2Register>{{cite web|title=New NASA snap of game developer's electric cart FOUND ON MOON: Probe in low pass over Garriott's radioactive tub-rover |url=https://www.theregister.co.uk/2012/03/16/moon_detailed_pic_landing_site_rover/ |author=Lewis Page |website=[[The Register]] |date=March 16, 2012 |access-date=May 25, 2013}}</ref><ref name=2012Lunokhod2Revisted>{{cite news |title=Lunokhod 2 Revisited |url=http://lroc.sese.asu.edu/news/?archives/537-Lunokhod-2-Revisited.html |publisher=NASA |date=March 13, 2012 |access-date=May 25, 2013}}</ref> Many mechanical tests of the surface, laser ranging measurements, and other experiments were completed during this time. ''Lunokhod 2'' was thought to have covered {{convert|37|km|mi|abbr=on}} based on wheel rotations but Russian scientists at the Moscow State University of Geodesy and Cartography (MIIGAiK) revised that to an estimated distance of about {{convert|42.1-42.2|km|mi|abbr=on}} based on Lunar Reconnaissance Orbiter ([[Lunar Reconnaissance Orbiter|LRO]]) images of the lunar surface.<ref>{{cite web|url=http://www.planetary.org/blogs/emily-lakdawalla/2013/06211627-opportunity-lunokhod-record.html |title=Is Opportunity near Lunokhod's distance record? Not as close as we used to think! |publisher=[[The Planetary Society]] |last1=Lakdawalla |first1=Emily |date=June 21, 2013 |access-date=June 26, 2013}}</ref><ref>{{cite journal |last1=Witze |first1=Alexandra |title=Space rovers in record race |journal=Nature |publisher=[[Nature News]] |date=June 19, 2013 |volume=498 |issue=7454 |pages=284–285 |doi=10.1038/498284a |pmid=23783609 |bibcode=2013Natur.498..284W |s2cid=4321213 |doi-access=free }}</ref> Subsequent discussions with their American counterparts ended with an agreed-upon final distance of {{convert|39|km|mi|abbr=on}};<ref name="sutherland">Sutherland, Scott (July 29, 2014)   [http://www.theweathernetwork.com/news/articles/its-official-nasa-confirms-mars-opportunity-rover-has-broken-the-off-world-driving-record/32813/ It's Official! NASA confirms Mars Opportunity rover has broken the off-world driving record]. theweathernetwork.com</ref><ref>Robinson, Mark (May 23, 2014) [http://lroc.sese.asu.edu/posts/774 Trundling Across the Moon]. sese.asu.edu</ref> an international team has confirmed that the methods used to calculate the two rovers' odometry is consistent and comparable from the Moon to Mars.<ref>Wall, Mike (July 29, 2014) [http://www.cbsnews.com/news/nasas-mars-rover-opportunity-breaks-off-world-driving-record/ NASA's Mars rover ''Opportunity'' breaks off-world driving record]. Space.com</ref>

''Lunokhod 2'' held the record for off-Earth roving distance until July 27, 2014, when NASA's Mars [[Opportunity (rover)|''Opportunity'' rover]] exceeded it after having traveled over {{convert|40|km|mi|abbr=on}}.<ref name="NASA-20140728a">{{cite web|last1=Webster |first1=Guy |last2=Brown |first2=Dwayne |title=NASA Long-Lived Mars Opportunity Rover Sets Off-World Driving Record |url=http://www.jpl.nasa.gov/news/news.php?release=2014-245 |date=July 28, 2014 |work=[[NASA]] |access-date=July 29, 2014}}</ref><ref name="FRB-20140729">{{cite web |last=Knapp |first=Alex |title=NASA's Opportunity Rover Sets A Record For Off-World Driving |url=https://www.forbes.com/sites/alexknapp/2014/07/29/nasas-opportunity-rover-sets-a-record-for-off-world-driving |date=July 29, 2014  |work=[[Forbes]] |access-date=July 29, 2014}}</ref>

== Current status ==

''Lunokhod 2'' continues to be detected by [[Lunar Laser Ranging experiment|lunar laser ranging experiments]] and its position is known to sub-meter accuracy.<ref>{{cite web|title=Lunar Geophysics, Geodesy, and Dynamics|url=http://ilrs.gsfc.nasa.gov/docs/williams_lw13.pdf|publisher=ilrs.gsfc.nasa.gov|access-date=February 6, 2008}}</ref>  On March 17, 2010, Phil Stooke at the [[University of Western Ontario]] announced that he had located ''Lunokhod 2'' in [[NASA]] [[Lunar Reconnaissance Orbiter]] (LRO) images,<ref name="space.com-2010">{{cite web|title=Russian Lunar Rover Found: 37-Year-Old Space Mystery Solved|url=https://www.sciencedaily.com/releases/2010/03/100316164950.htm|website=[[Science Daily]]|access-date=March 17, 2010}}</ref><ref>{{cite news | url = http://www.space.com/missionlaunches/moon-orbiter-spots-Soviet-landers-100318.html | title = NASA Lunar Orbiter Spots Old Soviet Moon Landers | first = Leonard | last = David | date = March 18, 2010  |access-date=May 31, 2018}} Space.com.</ref><ref name=garriott/> but later images showed the initial identification was incorrect (the identified point was a mark in the rover tracks near the end of the route, made as ''Lunokhod 2'' turned around), and the LRO LROC team identified the correct location of the rover in March 2012.<ref name=2012Lunokhod2Register/><ref>NASA, [https://www.nasa.gov/content/lroc-coordinates-of-robotic-spacecraft-2013-update/ LROC Coordinates of Robotic Spacecraft 2013], Update September 25, 2013. Retrieved May 31, 2018.</ref> Excellent ''Lunokhod 2'' images from LROC were published by Mark Robinson on SESE site of ASU.<ref>Mark Robinson, "[http://lroc.sese.asu.edu/posts/699 Lunokhod 2 Revisited"], LROC, SSE, Arizona State University. Retrieved May 31, 2018.</ref>

== 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.<ref name=garriott/><ref>Kluger, Jeffrey (April 1994) [http://discovermagazine.com/1994/apr/thebloconthebloc363 The Bloc on the Block]. Discover magazine</ref> (The catalog<ref>Sotheby's Catalogue – ''Russian Space History'', Addendum, Lot 68A, December 11, 1993</ref> incorrectly lists lot 68A as ''Luna 17''/''Lunokhod 1'').

The buyer was computer game entrepreneur and space tourist [[Richard Garriott]] (son of the astronaut [[Owen K. Garriott]]), who stated in a 2001 interview with ''[[Computer Games Magazine]]'''s Cindy Yans that:

: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]]!<ref>Garriott, Richard (April 13, 2001) [http://demiurg.net/games/lb/ Lord British, we hardly knew ye]. demiurg.net</ref>

Garriott later confirmed that he is the owner of ''Lunokhod 2''.<ref name=garriott>{{cite news |title= After 17 Years, a Glimpse of a Lunar Purchase |url=https://www.nytimes.com/2010/03/31/science/space/31moon.html?ref=science |quote=Richard A. Garriott has finally seen the item he bought 17 years ago for $68,500. |work=[[New York Times]] |date=March 20, 2010 |access-date=April 1, 2010 | first=Kenneth | last=Chang}}</ref><ref>[http://www.collectspace.com/news/news-100207a.html The Astronaut's Son's Secret Sputnik]. CollectSPACE. October 2007</ref><ref>[http://radio.seti.org/past-shows.php Are We Alone] {{webarchive|url=https://web.archive.org/web/20081219053216/http://radio.seti.org/past-shows.php |date=December 19, 2008 }}. (podcast interview with SETI Institute Director Seth Shostak) December 10, 2007</ref>

== See also ==
{{Portal|Spaceflight}}
* [[Exploration of the Moon]]
* [[Lunar rover]]
* ''[[Lunokhod 1]]''
* [[Rover (space exploration)]]
* [[Timeline of artificial satellites and space probes]]
* [[List of artificial objects on the Moon]]
* [[List of missions to the Moon]]

== References ==
{{reflist|30em}}

== External links ==
{{commons category|Lunokhod-2}}
* [http://www.zarya.info/Diaries/Luna/Luna21.php Zarya – ''Lunokhod 2'' chronology]
* [http://www.mentallandscape.com/C_CatalogMoon.htm Don P. Mitchell's catalog of Soviet Moon Images] including many from ''Lunokhod 2''
* [http://vsm.host.ru/e_lunhod.htm ''Lunokhod 2'' information and VRML models at the Virtual Space Museum]
* [http://planetology.ru/panoramas/lunokhod2.php?page=1&language=english ''Lunokhod 2'' panoramic images]
* [https://web.archive.org/web/20141205205158/http://www.strana360.net/panorama/3088 ''Lunokhod 2'' in space museum – 360 degree panoramic image]
* [http://www.planetary.org/multimedia/space-images/earth/lunokhod-2-traverse-overview.html ''Lunokhod 2'' traverse overview], ''Lunokhod 2''{{'}}s path in southern Le Monnier crater

{{Lunar Rovers}}
{{Moon spacecraft}}
{{Lavochkin aircraft}}
{{Orbital launches in 1973}}
{{Portal bar|Spaceflight}}

[[Category:Lunokhod programme|2]]
[[Category:1973 in the Soviet Union]]
[[Category:Missions to the Moon]]
[[Category:Lunar rovers]]
[[Category:1973 robots]]
[[Category:Robots of the Soviet Union]]
[[Category:Eight-wheeled robots]]
[[Category:Solar-powered robots]]
[[Category:Attached spacecraft]]
[[Category:Spacecraft launched in 1973]]
[[Category:1973 on the Moon]]