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{{Short description|Failed Soviet lunar sample return mission}}
{{italic title}}
{{Infobox spaceflight
| name                   = ''Luna 23''
| image                  = Luna23 figure.png
| image_caption          = Image of ''Luna 23'' lying horizontally on the lunar surface. A: Ascent Stage, D: Descent Stage. 

| mission_type           = [[Planetary Science|Lunar sample return]]
| operator               = Soviet space program
| COSPAR_ID              = 1974-084A
| SATCAT                 = 7491
| mission_duration       = {{time interval|28 October 1974|9 November 1974}}

| spacecraft_bus         = Ye-8-5M
| manufacturer           = [[Lavochkin|GSMZ Lavochkin]]
| dry_mass               = {{convert|5600|kg|abbr=on}}
| launch_mass            = {{Convert|5795|kg|abbr=on}}<ref name=beyond/>

| launch_date            = {{start-date|28 October 1974, 14:30:32|timezone=yes}}&nbsp;UTC<ref name=beyond/>
| launch_rocket          = [[Proton-K]]/[[Blok D|D]]
| launch_site            = [[Baikonur Cosmodrome|Baikonur]] [[Baikonur Cosmodrome Site 81|81/24]]
| launch_contractor      = 
| last_contact           = {{end-date|9 November 1974}}

| orbit_epoch            = 2 November 1974
| orbit_reference        = [[Selenocentric orbit|Selenocentric]]
| orbit_regime           = 
| orbit_periapsis        = {{Convert|94|km|abbr=on}}
| orbit_apoapsis         = {{Convert|104|km|abbr=on}}
| orbit_inclination      = 138&nbsp;degrees
| orbit_eccentricity     = 0.00272
| orbit_period           = 119&nbsp;minutes
| apsis                  = selene

| interplanetary         = {{Infobox spaceflight/IP
 | type             = orbiter
 | object           = [[Moon|Lunar]]
 | orbits           = ~48
 | arrival_date     = 2 November 1974
 }} {{Infobox spaceflight/IP
 | type             = lander
 | object           = [[Moon|Lunar]]
 | arrival_date     = 6 November 1974
 | location         = {{Lunar coords and quad cat|12.6669|N|62.1511|E}}<ref name=Lawrence_2013/>
 }} 

| instruments            = Stereo photographic imaging system<br/>Improved Drill/Remote arm for sample collection<br/>Radiation detector<br/>Radio-altimeter
| programme          = '''[[Luna programme]]'''
| previous_mission   = [[Luna 22]]
| next_mission       = ''[[Luna E-8-5M No.412|Luna 1975A]]''
}}
'''''Luna 23''''' was an [[uncrewed spacecraft|uncrewed space mission]] of the [[Luna program]] developed by the Soviet Union.

==Overview==
''Luna 23'' was a Soviet [[Moon]] lander mission which was intended to [[Sample return mission|return a lunar sample to Earth]]. Launched to the Moon by a [[Proton-K]]/[[Blok D|D]], the spacecraft tipped over on its side and was damaged upon landing in [[Mare Crisium]]. The sample collecting apparatus could not operate and no samples were returned. The lander continued transmissions for three days after landing. In 1976, ''[[Luna 24]]'' landed several hundred meters away and successfully returned samples. The asteroid-like object [[2010 KQ]] is believed to be a rocket that parted the ''Luna 23'' module after launch.<ref name=gomez_2012/>

''Luna 23'' was the first modified lunar sample return spacecraft, designed to return a deep core sample of the Moon's surface (hence the change in index from Ye-8-5 to Ye-8-5M). While ''[[Luna 16]]'' and ''[[Luna 20]]'' had returned samples from a depth of 0.3 meters, the new spacecraft was designed to dig to 2.5 meters. After a midcourse correction on 31 October, ''Luna 23'' entered orbit around the Moon on 2 November 1974. Parameters were 104 × 94 kilometers at 138° inclination. Following several more changes to the orbit, the spacecraft descended to the lunar surface on 6 November and landed in the southernmost portion of Mare Crisium. Landing coordinates were 13° north latitude and 62° east longitude. During landing in "unfavorable" terrain, the lander's drilling device was evidently damaged, preventing fulfillment of the primary mission, the return of lunar soil to Earth. Scientists devised a makeshift plan to conduct a limited science exploration program with the stationary lander. Controllers maintained contact with the spacecraft until 9 November 1974.

High resolution orbital photographs taken by the NASA [[Lunar Reconnaissance Orbiter]] and released in March 2012 showed the ''Luna 23'' spacecraft lying on its side on the lunar surface.  The spacecraft evidently tipped over upon landing, perhaps due to higher than nominal vertical and/or horizontal velocities at touchdown.<ref name=lroc/>

==In culture==
In the 2007 [[BioWare]] video game ''[[Mass Effect (video game)|Mass Effect]]'', derelict remains of this spacecraft can be found in the accessible parts of Earth's Moon and can be salvaged for random materials.

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

==References==
{{Reflist|refs=

<ref name="Lawrence_2013">
{{ cite web
| url= http://lroc.sese.asu.edu/posts/650
| title= LROC Coordinates of Robotic Spacecraft - 2013 Update
| author= Samuel Lawrence
| website= lroc.sese.asu.edu
| date= 24 September 2013
| access-date= 9 June 2015
| archive-url= https://web.archive.org/web/20150509061816/http://lroc.sese.asu.edu/posts/650
| archive-date= 9 May 2015
| url-status= live }}
</ref>

<ref name="lroc">
{{ Cite news
| url= http://lroc.sese.asu.edu/posts/461
| title= Mare Crisium: Failure then Success
| date= 16 March 2012
| website= lroc.sese.asu.edu
| author1= Jeff Plescia
| access-date= 13 September 2014
| archive-date= 30 June 2018
| archive-url= https://web.archive.org/web/20180630161557/http://lroc.sese.asu.edu/posts/461 
| url-status= live }}
</ref>

<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
| author1= Asif Siddiqi
| publisher= NASA History Program Office
| edition= second
| year= 2018
| isbn= 9781626830431 }}
</ref>

<ref name="gomez_2012">
{{ cite web
| url= http://lcogt.net/en/blog/egomez/man-made-object-spotted-ftn
| title= Man-made object spotted with FTN
| archive-url= https://archive.today/20120630184904/http://lcogt.net/en/blog/egomez/man-made-object-spotted-ftn
| archive-date= 30 June 2012
| url-status= dead
| author1= Edward Gomez
| date= 26 May 2010 }}
</ref>
}}

==External links==
* [http://www.zarya.info/Diaries/Luna/Luna.php Zarya - Luna programme chronology]
* [https://nssdc.gsfc.nasa.gov/nmc/spacecraft/display.action?id=1974-084A NASA NSSDC Master Catalog]

{{Luna programme}}
{{Orbital launches in 1974}}
{{Moon spacecraft}}

[[Category:Luna programme]]
[[Category:Sample return missions]]
[[Category:Missions to the Moon]]
[[Category:1974 in spaceflight]]
[[Category:1974 in the Soviet Union]]
[[Category:Soft landings on the Moon]]
[[Category:Spacecraft launched in 1974]]
[[Category:1974 on the Moon]]