Editing Apollo Lunar Module (section)

{{Short description|NASA crewed Moon landing spacecraft (1969–1972)}}
{{Use mdy dates|date=September 2022}}
{{Infobox spacecraft class
| name = Apollo Lunar Module
| image = Apollo 14 Lunar Module (LM) on the moon.jpg
| image_size = 
| image_alt = 
| image_caption = [[Apollo 14]] Lunar Module ''Antares'' on the Moon's surface, February 1971
| manufacturer = [[Grumman]]
| designer = [[Thomas J. Kelly (aerospace engineer)|Thomas J. Kelly]]
| country = United States
| operator = [[NASA]]
| applications = Crewed [[Moon landing|lunar landing]]

<!--Specifications-->| spacecraft_type = [[Lunar lander]]
| spacecraft_bus = 
| constellation = 
| design_life = 75 hours (extended)
| launch_mass = {{plainlist|
*{{convert|33500|lb|kg|abbr=on}} standard
*{{convert|36200|lb|kg|abbr=on}} extended
}}
| dry_mass = {{plainlist|
*{{convert|9430|lb|kg|abbr=on}} standard
*{{convert|10850|lb|kg|abbr=on}} extended
}}
| payload_capacity = 
| crew_capacity = 2
| volume = {{convert|235|cuft|m3|abbr=on}}
| power = 28 V DC, 115 V 400&nbsp;Hz AC
| batteries = Six or seven 28–32-volt, 296 [[ampere hour]] [[silver-oxide battery|silver-zinc]]
| equipment = 
| orbits = {{unbulleted list|[[Lunar orbit]]|[[Lunar landing]]}}

<!--Dimensions-->| length = {{convert|23|ft|1|in|m|abbr=on}}
| diameter = {{convert|13|ft|10|in|m|abbr=on}} without landing gear
| width = {{convert|31|ft|m|abbr=on}}, landing gear deployed
| winged = 
| span = <!--Production-->
| status = Retired
| built = 15
| orders = 
| launched = 10
| operational = 10
| retired = 1972
| failed = 0
| lost = 0
| maidenlaunch = January 22, 1968
| lastlaunch = December 7, 1972
| lastretired = December 14, 1972

<!--insignia-->| insignia = 
| insignia_size = 
| insignia_alt = 
| insignia_caption = <!--Engine details-->
{{Infobox rocket/stage
| name                 = Descent stage
| engines              = One [[Descent propulsion system|VTR-10]]
| thrust               = {{convert|10500|lbf|kN|abbr=on}}
| SI                   = {{plainlist|
* {{convert|311|isp|abbr=on}} (at full thrust)
* {{convert|285|isp|abbr=on}} (10% thrust)
}}
| burntime             =  1030 sec
| fuel                 = [[Aerozine 50]]/[[N2O4|N<sub>2</sub>O<sub>4</sub>]]
}}
{{Infobox rocket/stage
| name                 = Ascent stage
| engines              = One [[Ascent propulsion system|LMAE]]
| thrust               = {{cvt|3500|lbf|kN}}
| SI                   = {{cvt|311|isp}}
| burntime             =  465 s
| fuel                 = [[Aerozine 50]]/[[N2O4|N<sub>2</sub>O<sub>4</sub>]]
}}

<!--Related spacecraft-->| subsatellites = 
| flown_with = [[Apollo Command and Service Module]]

<!--Configuration image -->| configuration_image = LEM-linedrawing.png
| configuration_size = <!--285px-->
| configuration_alt = 
| configuration_caption = Apollo LM diagram
| previous = 
| next = 
}}

The '''Apollo Lunar Module''' ('''LM''' {{IPAc-en|ˈ|l|ɛ|m}}), originally designated the '''Lunar Excursion Module''' ('''LEM'''), was the [[lunar lander]] [[spacecraft]] that was flown between [[lunar orbit]] and the Moon's surface during the United States' [[Apollo program]]. It was the first crewed spacecraft to operate exclusively in the airless vacuum of space, and remains the only crewed vehicle to land anywhere beyond Earth.

Structurally and aerodynamically incapable of flight through Earth's atmosphere, the [[Multistage rocket |two-stage]] Lunar Module was ferried to lunar orbit attached to the [[Apollo command and service module]] (CSM), about twice its mass. Its crew of two flew the Lunar Module from lunar orbit to the Moon's surface. During takeoff, the spent descent stage was used as a launch pad for the ascent stage which then [[Lunar orbit rendezvous|flew back to the command module]], after which it was also discarded.

Overseen by [[Grumman]], the LM's development was plagued with problems that delayed its first uncrewed flight by about ten months and its first crewed flight by about three months. Regardless, the LM became the most reliable component of the Apollo–Saturn [[space vehicle]].<ref>''Moon Race: The History of Apollo'' DVD, Columbia River Entertainment (Portland, Oregon, 2007)</ref>  The total cost of the LM for development and the units produced was $21.65&nbsp;billion in 2016 dollars, adjusting from a nominal total of $2.29&nbsp;billion<ref>{{Cite book|url=http://georgetyson.com/files/apollostatistics.pdf|title=Apollo by the Numbers|last=Orloff|first=Richard|publisher=[[National Aeronautics and Space Administration]]|year=1996|page=22|access-date=May 23, 2016|archive-date=February 22, 2016|archive-url=https://web.archive.org/web/20160222011513/http://georgetyson.com/files/apollostatistics.pdf|url-status=live}}</ref> using the NASA New Start Inflation Indices.<ref>{{cite web|url=http://www.nasa.gov/sites/default/files/files/2013_NNSI_FY14(1).xlsx|title=NASA New Start Inflation Indices|publisher=National Aeronautics and Space Administration|access-date=May 23, 2016|archive-date=June 24, 2016|archive-url=https://web.archive.org/web/20160624014744/http://www.nasa.gov/sites/default/files/files/2013_NNSI_FY14(1).xlsx|url-status=live}}</ref>

Ten Lunar Modules were launched into space. Of these, six were landed by humans on the Moon from 1969 to 1972. The first two flown were tests in [[low Earth orbit]]: [[Apollo 5]], without a crew; and [[Apollo 9]] with a crew.  A third test flight in low lunar orbit was [[Apollo 10]], a dress rehearsal for the first landing, conducted on [[Apollo 11]]. The [[Apollo 13]] Lunar Module functioned as a lifeboat to provide life support and propulsion to keep the crew alive for the trip home, when their CSM was disabled by an oxygen tank explosion ''en route'' to the Moon.

The six landed descent stages remain at their landing sites; their corresponding ascent stages crashed into the Moon following use. One ascent stage (Apollo 10's ''Snoopy'') was discarded in a [[heliocentric orbit]] after its descent stage was discarded in lunar orbit.<ref>{{Cite web |last=Dickinson |first=David |date=14 June 2019 |title=ASTRONOMERS MIGHT HAVE FOUND APOLLO 10'S "SNOOPY" MODULE |url=https://skyandtelescope.org/astronomy-news/astronomers-might-have-found-apollo-10-snoopy-module/}}</ref> The other three LMs were destroyed during controlled re-entry in the Earth's atmosphere: the four stages of [[Apollo 5]] and [[Apollo 9]] each re-entered separately, while Apollo 13's ''Aquarius'' re-entered as a unit.