Editing Luna 21

{{Short description|Soviet lunar lander that carried the Lunokhod 2 rover to the Moon}}
{{Use dmy dates|date=May 2020}}
{{italic title}}
{{Infobox spaceflight
| name               = ''Luna 21''
| names_list         = 

<!--image of the spacecraft/mission-->
| image              = Luna 21 lander.png
| image_caption      = Luna 21 as seen from orbit by the [[Lunar Reconnaissance Orbiter|LRO]] in March 2010
| image_alt          = 
| image_size         = 

<!--Basic details-->
| mission_type       = [[Planetary Science]]
| operator           = Soviet space program
| COSPAR_ID          = 1973-001A
| SATCAT             = 6333
| website            = 
| mission_duration   = 8 days (day of launch to day of landing)
| distance_travelled = 
| orbits_completed   = 
| suborbital_range   = 
| suborbital_apogee  = 

<!--Spacecraft properties-->
| spacecraft         = s/n 204
| spacecraft_type    = Ye-8
| spacecraft_bus     = 
| manufacturer       = [[Lavochkin|GSMZ Lavochkin]]
| launch_mass        = {{Convert|5700|kg|abbr=on}}<ref name=beyond>{{cite book|url=https://www.nasa.gov/sites/default/files/atoms/files/beyond-earth-tagged.pdf|title=Beyond Earth: A Chronicle of Deep Space Exploration, 1958–2016|last1=Siddiqi|first1=Asif|publisher=NASA History Program Office|edition=second|year=2018|isbn=9781626830431}}</ref>
| BOL_mass           = 
| landing_mass       = 
| dry_mass           = {{convert|4850|kg|abbr=on}}
| payload_mass       = 
| dimensions         = 
| power              = 

<!--Launch details-->
| launch_date        = {{start date|1973|01|08|06|55|38|7=Z|df=yes}}<ref name=beyond/>
| launch_rocket      = [[Proton-K]]/[[Blok D|D]]
| launch_site        = [[Baikonur Cosmodrome|Baikonur]] [[Baikonur Cosmodrome Site 81|81/23]]
| launch_contractor  = 
| deployment_from    = 
| deployment_date    = 
| entered_service    = 

<!--end of mission-->
| disposal_type      = 
| deactivated        = 
| destroyed          = 
| last_contact       = 
| recovery_by        = 
| recovery_date      = 
| decay_date         = 
| landing_date       = 
| landing_site       =

<!--
    The following template should be used for ONE of the three above fields "end_of_mission", "decay" or "landing" if the spacecraft is no longer operational.
    If it landed intact, use it for the landing time, otherwise for the date it ceased operations, or the decay date if it was still operational when it re-entered.
    {{end date|YYYY|MM|DD|hh|mm|ss|TZ=Z}} (for Zulu/UTC) or {{end date|YYYY|MM|DD}} (if time unknown) 
-->

<!--orbit parameters-->
<!--as science-related articles, SI units should be the principal units of measurement, however we usually use {{convert}} to display imperial units in parentheses after the initial values-->
| orbit_reference    = [[Lunar orbit|Selenocentric]]
| orbit_regime       = 
| orbit_longitude    = 
| orbit_slot         = 
| orbit_semimajor    = 
| orbit_eccentricity = 
| orbit_periapsis    = {{Convert|90|km|abbr=on}}
| orbit_apoapsis     = {{Convert|100|km|abbr=on}}
| orbit_inclination  = 60°
| orbit_period       = 
| orbit_RAAN         = 
| orbit_arg_periapsis = 
| orbit_mean_anomaly = 
| orbit_mean_motion  = 
| orbit_repeat       = 
| orbit_velocity     = 
| orbit_epoch        = 
| orbit_rev_number   = 
| apsis              = selene
| interplanetary     = <!--Infobox spaceflight/IP can be called multiple times for missions with multiple targets or combined orbiter/lander missions, etc-->
 {{Infobox spaceflight/IP
   |type                = orbiter
   |object              = [[Moon]]
   |orbits              = ~36
   |component           = <!--part of the spacecraft involved, if spacecraft split into multiple components-->
   |arrival_date        = 12 January 1973
   |departure_date      = <!--Date of leaving orbit for orbiters, date of launch for landers which took off again-->
   |location            = <!--landing/impact site, including EOM impacts for atmospheric probes and lunar/asteroid orbiters-->
   |distance            = <!--closest approach distance for flybys, distance travelled on surface for rovers, omit for others-->
   |sample_mass         = <!--mass of samples returned (sample return missions only)-->
   |surface_EVAs        = <!--number of EVAs on the surface-->
   |surface_EVA_time    = 
 }}

{{Infobox spaceflight/IP
   |type                = lander
   |object              = [[Moon]]
   |orbits              = <!--number of orbits completed at target body (if applicable and known)-->
   |component           = <!--part of the spacecraft involved, if spacecraft split into multiple components-->
   |arrival_date        = 22:35, 15 January 1973
   |departure_date      = <!--Date of leaving orbit for orbiters, date of launch for landers which took off again-->
   |location            = {{Coord|25.85|N|30.45|E|globe:Moon|display=inline}}<ref>{{cite web|url = https://nssdc.gsfc.nasa.gov/nmc/spacecraft/display.action?id=1973-001A|title = NASA NSSDC Master Catalog - Luna 21/Lunokhod 2|access-date = 1 January 2011}}</ref>   |distance            = <!--closest approach distance for flybys, distance travelled on surface for rovers, omit for others-->
   |sample_mass         = <!--mass of samples returned (sample return missions only)-->
   |surface_EVAs        = <!--number of EVAs on the surface-->
   |surface_EVA_time    = <!--time spent on surface EVAs-->
   
   <!--Orbit parameters, ONLY USE IF THE ABOVE ORBIT PARAMETERS SECTION DOESN'T APPLY TO THE TARGET-->
   |periapsis           = <!--periapsis altitude-->
   |apoapsis            = <!--apoapsis altitude--> 
   |inclination         = <!--inclination to the object's equator-->
   |apsis               = <!--planet specific apsis term, as above-->
 }}

{{Infobox spaceflight/IP
   |type                = rover
   |object              = [[Moon]]
   |orbits              = <!--number of orbits completed at target body (if applicable and known)-->
   |component           = ''[[Lunokhod 2]]''
   |arrival_date        = 01:14, 16 January 1973
   |departure_date      = <!--Date of leaving orbit for orbiters, date of launch for landers which took off again-->
   |location            = <!--landing/impact site, including EOM impacts for atmospheric probes and lunar/asteroid orbiters-->
   |distance            = {{Convert|42|km|abbr=on}}
   |sample_mass         = <!--mass of samples returned (sample return missions only)-->
   |surface_EVAs        = <!--number of EVAs on the surface-->
   |surface_EVA_time    = <!--time spent on surface EVAs-->
   
   <!--Orbit parameters, ONLY USE IF THE ABOVE ORBIT PARAMETERS SECTION DOESN'T APPLY TO THE TARGET-->
   |periapsis           = <!--periapsis altitude-->
   |apoapsis            = <!--apoapsis altitude--> 
   |inclination         = <!--inclination to the object's equator-->
   |apsis               = <!--planet specific apsis term, as above-->
 }}

<!--transponder parameters-->| trans_band         = <!--Transponder frequency bands-->
| trans_frequency    = <!--specific frequencies-->
| trans_bandwidth    = <!--bandwidth-->
| trans_capacity     = <!--capacity of the transponders-->
| trans_coverage     = <!--area covered-->
| trans_TWTA         = <!--TWTA output power-->
| trans_EIRP         = <!--equivalent isotropic power-->
| trans_HPBW         = <!--half-power beam width-->

<!--Only use where a spacecraft/mission is part of a clear programme of sequential missions. 
If in doubt, leave it out-->
| programme          = '''[[Luna programme]]'''
| previous_mission   = [[Luna 20]]
| next_mission       = [[Luna 22]]

<!--mission insignia or patch-->
| insignia           = <!--omit the "file" prefix-->
| insignia_caption   = <!--image caption-->
| insignia_alt       = <!--image alt text-->
| insignia_size      = <!--include px/em; defaults to 180px-->
| instruments_list   = {{Infobox spaceflight/Instruments
  |name1=Photographic imaging system
  |name2=[[X-ray spectrometer]]
  |name3=[[Penetrometer]]
  |name4=Laser reflector
  |name5=Radiation detectors
  |name6=X-ray telescope
  |name7=Odometer/Speedometer
  |name8=Visible/ultraviolet [[photometer]]
  |name9=[[Magnetometer]]
  |name10=[[Photodetector]]
 }}
}}
<!--| Refs                   = [https://nssdc.gsfc.nasa.gov/nmc/spacecraft/display.action?id=1973-001A NASA NSSDC Master Catalog]-->

'''''Luna 21''''' (Ye-8 series) was an [[uncrewed space mission]], and its spacecraft, of the [[Luna program]], also called '''''Lunik 21''''', in 1973. The spacecraft landed on the Moon and deployed the second [[Soviet Union|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.

== Mission ==
[[File:Luna and Lunokhod.png|left|thumb|<nowiki>''Luna'' spacecraft with ''Lunokhod''</nowiki> payload]]
''Luna 21'' carried the second successful Soviet lunar rover, ''Lunokhod 2'', and was launched less than a month after the last Apollo lunar landing. The [[Proton-K]]/[[Blok D|D]] launcher put the spacecraft into Earth [[parking orbit]] followed by [[translunar injection]]. On 12 January 1973, ''Luna 21'' was braked into a 90 × 100&nbsp;km orbit about the Moon, at a 60° inclination. On 13 and 14 January, the [[perilune]] was lowered to 16&nbsp;km altitude. On 15 January after 40 orbits, the [[braking rocket]] was fired at 16&nbsp;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 [[Le Monnier (crater)|Le Monnier crater]] at 25.85°  N, 30.45° E, between [[Mare Serenitatis]] ("Sea of Serenity") and the [[Montes Taurus|Taurus Mountains]]. The lander carried a [[Relief#Low relief or bas-relief|bas-relief]] of [[Vladimir Lenin]] and the Soviet coat-of-arms.

Less than three hours later, at 01:14 UT on 16 January, the rover disembarked onto the lunar surface. The 840&nbsp;kilogram ''Lunokhod 2'' was an improved version of its predecessor and was equipped with a third TV camera, an improved eight-wheel traction system, and additional scientific instrumentation. By the end of its first lunar day, ''Lunokhod 2'' had already traveled further than ''Lunokhod 1'' in its entire operational life. On 9 May, the rover inadvertently rolled into a crater and dust covered its solar panels and radiators, disrupting temperatures in the vehicle. Attempts to save the rover failed, and on 3 June, the [[Telegraph Agency of the Soviet Union|Soviet news agency]] announced that its mission was over. Before last contact, the rover took 80,000 TV pictures and 86 panoramic photos and had performed hundreds of mechanical and chemical surveys of the soil. The Soviets later revealed that during a conference on planetary exploration in Moscow, 29 January to 2 February 1973 (that is, after the landing of ''Luna 21''), an American scientist had given photos of the lunar surface around the ''Luna 21'' landing site to a Soviet engineer in charge of the ''Lunokhod 2'' mission. These photos, taken prior to the Apollo 17 landing, were later used by the "driver team" to navigate the new rover on its mission on the Moon
*Launch Date/Time: 1973-01-08 at 06:55:38 UTC
*On-orbit dry mass: 4850&nbsp;kg

== Present ownership ==
''Luna 21'' and ''[[Lunokhod 2]]'', still on the Moon, were purchased by [[Richard Garriott]] in December 1993 at a Sotheby's auction in New York.

==See also==
{{Portal|Solar System|Spaceflight}}
*''[[Lunokhod 2]]''
*[[Lunokhod programme]]
*[[Timeline of artificial satellites and space probes]]
*[[List of artificial objects on the Moon]]
*[[List of missions to the Moon]]

==References==
{{Reflist}}

== External links ==
* [http://www.zarya.info/Diaries/Luna/Luna21.php Zarya - ''Luna 21'' chronology]

{{Luna programme}}
{{Lunar Rovers}}
{{Moon spacecraft}}
{{Orbital launches in 1973}}

[[Category:Luna programme]]
[[Category:1973 in spaceflight]]
[[Category:1973 in the Soviet Union]]
[[Category:Soft landings on the Moon]]
[[Category:Spacecraft launched in 1973]]
[[Category:1973 on the Moon]]