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{{short description|Uncrewed first test flight of the Apollo Lunar Module}}
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{{Infobox spaceflight
| name                  = Apollo 5
| image                 = Lunar Module-1 and Spacecraft Lunar Module Adapter (SLA)-7 in the Kennedy Space Center's Manned Spacecraft Operations Building.jpg
| image_caption         = Lunar Module 1 being mated to the [[Apollo (spacecraft)#Spacecraft Lunar Module Adapter (SLA)|Spacecraft–LM adapter]] (SLA) in preparation for launch as Apollo&nbsp;5
| insignia              =
| mission_type          = Uncrewed Earth orbital LM flight ([[List of Apollo missions#Alphabetical mission types|B]])
| operator              = [[NASA]] 
| COSPAR_ID             = {{ubl|Ascent stage: 1968-007A|Descent stage: 1968-007B|S-IVB: 1968-007C}}
| SATCAT                = 3106
| mission_duration      = 11&nbsp;hours, 10&nbsp;minutes
| orbits_completed      = 7
| spacecraft            = [[Apollo Lunar Module]]-1
| manufacturer          = [[Grumman]]
| launch_mass           = {{convert|14360|kg|lb}}<ref name="orbital_info"/>
| launch_date           = {{start-date|January 22, 1968, 22:48:09|timezone=yes}}&nbsp;UTC 
| launch_rocket         = [[Saturn IB]] SA-204
| launch_site           = [[Cape Canaveral Space Force Station|Cape Kennedy]] [[Cape Canaveral Air Force Station Space Launch Complex 37|LC-37B]]
| disposal_type         = Uncontrolled reentry
| deactivated           = {{End-date|January 23, 1968 9:58|timezone=yes}}&nbsp;UTC
| decay_date            = {{Ubl|Ascent stage: {{end-date|January 24, 1968}}|Descent stage: {{end-date|February 12, 1968}}}}
| orbit_epoch           = January 22, 1968<ref name=satcat>{{cite web|last=McDowell|first=Jonathan|authorlink=Jonathan McDowell|title=SATCAT|url=http://planet4589.org/space/log/satcat.txt|publisher=Jonathan's Space Pages|access-date=March 23, 2014}}</ref>
| orbit_reference       = [[geocentric orbit|Geocentric]]
| orbit_regime          = [[Low Earth orbit]]
| orbit_periapsis       = {{convert|167|km|nmi|sp=us}}<ref name="orbital_info">{{cite web|url=https://nssdc.gsfc.nasa.gov/nmc/spacecraft/display.action?id=1968-007A|title=Apollo 5|access-date=September 26, 2016|website=NASA Space Science Data Coordinated Archive}}</ref>
| orbit_apoapsis        = {{convert|222|km|nmi|sp=us}}<ref name="orbital_info" />
| orbit_inclination     = 31.63&nbsp;degrees<ref name="orbital_info" />
| orbit_period          = 88.4&nbsp;minutes<ref name="orbital_info" />
| apsis                 = gee
| previous_mission      = [[Apollo 4]]
| next_mission          = [[Apollo 6]]
| programme             = [[Apollo program]]
}}

'''Apollo 5''' (launched January&nbsp;22, 1968), also known as '''AS-204''', was the uncrewed first flight of the [[Apollo Lunar Module]] (LM) that would later carry [[astronaut]]s to the surface of the Moon. The [[Saturn IB]] rocket bearing the LM lifted off from [[Cape Canaveral Space Force Station|Cape Kennedy]] on January&nbsp;22, 1968. The mission was successful, though due to programming problems an alternate mission to that originally planned was executed.

Like [[Apollo 4]], this flight was long delayed, due in part to setbacks in development of the LM, manufactured by [[Grumman|Grumman Aircraft]]. The original Saturn IB rocket that was to take the first LM (LM-1) to space was taken down during the delays and replaced with the one that would have launched [[Apollo 1]] if the spacecraft fire that killed three astronauts had not occurred. [[Apollo Lunar Module|LM-1]] arrived at the [[Kennedy Space Center]] in June 1967; the following months were occupied in testing and placing the LM atop the Saturn IB. After final delays due to equipment trouble, the countdown began on January&nbsp;21, 1968, and the space vehicle was launched the following day.

Once the craft reached orbit and the LM separated from the [[S-IVB]] booster, the program of orbital testing began, but a planned burn was aborted automatically when the [[Apollo Guidance Computer]] detected the craft was not going as fast as planned. Flight Director [[Gene Kranz]] and his team at [[Christopher C. Kraft Jr. Mission Control Center|Mission Control]] in [[Houston, Texas|Houston]] quickly decided on an alternate mission, during which the mission's goals of testing LM-1 were accomplished. The mission was successful enough that a contemplated second uncrewed mission to test the LM was cancelled, advancing [[NASA]]'s plans to land an astronaut on the Moon by the end of the 1960s.

== Background ==

In 1961, United States President [[John F. Kennedy]] [[We choose to go to the Moon|challenged the United States]] to land an astronaut on the [[Moon]] by the end of the decade, with a safe return to Earth.<ref name = "mission overview">{{cite web|title=Apollo 11 Mission Overview|url=https://www.nasa.gov/mission_pages/apollo/missions/apollo11.html|date=December 21, 2017|access-date=February 14, 2019|publisher=[[NASA]]}}</ref> After considerable debate, [[NASA]] (the US government's spaceflight agency) decided in late 1962 that lunar missions would use a [[lunar orbit rendezvous]] in which the complete [[Apollo spacecraft]] would be propelled towards lunar orbit by the [[Saturn V]] launch vehicle's third stage (called the [[S-IVB]]). Once in lunar orbit, those astronauts who would land on the Moon would enter what was then called the lunar excursion module (LEM) (later called the [[Apollo Lunar Module|lunar module]] (LM)). This craft would separate from the Apollo's command and service module (CSM) and land on the Moon. When the astronauts were ready to return, they would enter the LM, take off, and re-dock with the CSM. Once the crew reentered the CSM, they would discard the lunar module and return to Earth in the CSM.{{sfn|Orloff & Harland 2006|pp=25–26}} In 1962, NASA invited eleven companies to bid for the contract to construct the LM. On November&nbsp;7, 1962, NASA announced that it had awarded the contract to [[Grumman]] in [[Bethpage, New York]].{{sfn|Orloff & Harland 2006|p=26}}

==Delays==
As with [[Apollo 4]], there were significant delays for Apollo&nbsp;5. The primary cause of the Apollo&nbsp;5 delays was the LM, which was behind schedule. Apollo Program Manager [[Major general (United States)|Major General]] [[Samuel C. Phillips]] had originally hoped that the uncrewed test flight of LM-1, the first lunar module, would launch in April 1967. Anticipating six months for checkout and testing of the vehicle, NASA asked Grumman to have LM-1 delivered to [[Kennedy Space Center]] in Florida by September 1966, but due to difficulties in manufacturing LM-1, delivery was repeatedly delayed. The delivery date was still uncertain when AS-206, the [[Saturn IB]] launch vehicle planned to boost LM-1 to orbit, was erected at [[Cape Canaveral Space Launch Complex 37|Launch Complex 37]] in January 1967. After the fire that month that killed the [[Apollo 1]] crew, the launch vehicle planned for Apollo&nbsp;1, AS-204, was moved from [[Launch Complex 34]] to Launch Complex&nbsp;37 and replaced AS-206.{{sfn|Benson|Faherty|1978|p=435}} This was done because AS-204 was the last Saturn IB with full research and development instrumentation, and, with crewed flight on hold, NASA wanted to use that booster for the first flight of the LM.{{sfn|Astronautics 1967|p=81}}{{efn|Launch vehicle AS-206 was subsequently designated for a potential second uncrewed flight of the LM, and when this proved unnecessary, was placed in long-term storage. It was renovated for crewed flight and flew in 1973 as the launch vehicle for [[Skylab 2]], taking the first crew to [[Skylab|that space station]].<ref>{{cite web|last=LaPage|first=Andrew|work=Drew ex Machina|title=SA-206: The Odyssey of a Saturn IB|url=https://www.drewexmachina.com/2018/05/25/sa-206-the-odyssey-of-a-saturn-ib/|date=May 25, 2018|access-date=September 12, 2021}}</ref>}}

With no LM yet available, Grumman built a plywood mockup of one at Launch Complex&nbsp;37 to aid in facilities verification.{{sfn|Orloff & Harland 2006|p=139}} On May&nbsp;12, 1967, Apollo Program Spacecraft Manager [[George M. Low]] informed NASA headquarters that Grumman was committed to a June&nbsp;28 delivery of LM-1, though Low noted that the goal would be hard to meet.{{sfn|Ertel et al|p=132}} On June&nbsp;23, LM-1 arrived at Cape Kennedy on board [[Aero Spacelines]]' [[Aero Spacelines Super Guppy|Super Guppy]]; the stages were mated to each other four days later.{{sfn|Orloff & Harland 2006|p=139}}{{sfn|Brooks 1979|p=241}} A 400-person team under John J. Williams, a veteran of launch operations for both [[Mercury program|Mercury]] and [[Gemini program|Gemini]], checked to see that LM-1 met specifications, after which they supervised Grumman technicians, who tested and modified the vehicle.{{sfn|Brooks 1979|p=241}} Due to leaks in the LM's ascent stage, the two stages were demated in August, and after these were fixed and the stages remated, another leak developed and the stages were demated again in September. During this time, several pieces of equipment were removed for repair by Grumman; the stages were remated again in October.{{sfn|Orloff & Harland 2006|p=139}}

As of September&nbsp;6, 1967, Apollo&nbsp;5 was running about 39&nbsp;days behind the plan established on July&nbsp;18, but all known issues were being dealt with, with the exception of some leaks from the propulsion system.{{sfn|Ertel et al|pp=153–154}} Most mission documents were ready by late 1967; Mission Director [[William C. Schneider]] issued mission rules on November&nbsp;18, 1967. The following day, LM-1 was mated to its launch vehicle, and the space vehicle readiness test was completed in December. In early January 1968, the office of NASA Administrator [[James E. Webb]] announced that Apollo 5 would be launched no earlier than January&nbsp;18, 1968. Minor faults such as clogged filters led to some additional delays. The countdown demonstration test concluded on January&nbsp;19 and an abbreviated 22-hour countdown began on January&nbsp;21.{{sfn|Brooks 1979|p=242}}{{sfn|Orloff & Harland 2006|p=140}}

==Objectives==
[[File:Lunar Module-1 arrival at Kennedy Space Center.jpg|thumb|left|alt=A large plane has opened to show its interior, in which there is a huge packing crate (LM-1)|LM-1 is delivered by [[Super Guppy]] aircraft, June 23, 1967]]
Apollo&nbsp;5 was intended to verify the operation of the subsystems of the LM. During the flight, the ascent and descent engines would be fired. A "[[fire in the hole]]" test would be conducted to verify that the ascent stage could still fire while attached to the descent stage, a procedure that would be used on the lunar surface and in the event of an aborted lunar landing. It involved shutting down the descent stage, switching control and power to the ascent stage, and starting the ascent engine while the two stages were still mated. The term "fire in the hole" derived from a term used in mining when explosives are about to be used.{{sfn|Brooks 1979|p=242}}{{sfn|Press Kit|pp=2–4}}{{sfn|Kranz 2000|p=215}} Additional testing was to check that the LM engines could be restarted after initial use.{{sfn|Press Kit|p=2}} In addition to testing LM systems, Apollo&nbsp;5 was to test the [[Saturn V instrument unit|Instrument Unit]] in its Saturn&nbsp;V configuration.{{sfn|Orloff & Harland 2006|p=139}}

It was expected that the ascent stage of LM-1 would remain in orbit for about two years before re-entering the atmosphere and disintegrating, and the descent stage for about three weeks.{{sfn|Press Kit|p=5}} 
{{clear}}

==Equipment==
[[File:Apollo 5 on pad.jpg|thumb|right|alt=A rocket sits on a launchpad|Apollo 5's [[Saturn IB]] on the launchpad]]
Apollo&nbsp;5 was launched into orbit by the Saturn&nbsp;IB, designated SA-204R, which had been assigned to Apollo&nbsp;1. Originally brought to Cape Kennedy in August 1966, it had survived the fire unscathed, having been inspected after the fire for corrosion or other damage.{{sfn|Orloff & Harland 2006|p=139}}{{sfn|Brooks 1979|p=241}}{{sfn|Press Kit|p=20}} Ignition weight for the launch vehicle, including the spacecraft and propellant, was {{convert|1299434|lb|order=flip}}.{{sfn|Press Kit|p=19}}

The [[space vehicle]] for this mission was {{convert|55|m|sp=us}} tall but had a stubby appearance since it had neither a CSM nor a launch escape system. Instead, the LM was housed within the spacecraft-lunar module adapter (SLA) at the top of the vehicle stack.{{sfn|Brooks 1979|p=241}} The SLA, numbered as SLA-7,<ref name = "hardware">{{cite web|title=Apollo/Skylab ASTP and Shuttle Orbiter Major End Items|date=March 1978|url=https://s3.documentcloud.org/documents/6473665/Apollo-Skylab-ASTP-and-Shuttle-Orbiter-Major-End.pdf|publisher=[[NASA]]|page=10}}</ref> was just below the nose cap in the stack, and had four panels that would open once the nose cap was jettisoned in orbit, allowing the LM room to separate and move away.{{sfn|Press Kit|pp=9–10}}

The LM, designated as LM-1, was the first flight-ready Apollo lunar module. To save weight, and because they would not be necessary during the test mission, LM-1 had no landing legs.<ref name = "legs">{{cite web|title=50 Years Ago: The Apollo Lunar Module|access-date=September 11, 2021|date=January 24, 2018|publisher=[[NASA]]|url=https://www.nasa.gov/feature/50-years-ago-the-apollo-lunar-module}}</ref>

After one of the windows of [[Lunar Module Eagle|LM-5]] (which would fly on [[Apollo 11]]) broke during testing in December 1967, NASA officials decided to replace the windows of LM-1 with aluminum plates out of concern a window might fail in flight.{{sfn|Ertel et al|pp=185, 190}} Since there would be no astronauts aboard, LM-1 had a mission programmer installed, which could control the craft remotely.{{sfn|Press Kit|p=6}} Not all LM-1 systems were fully activated nor was it given a full load of consumables: for example, its primary batteries were partially discharged to avoid over-voltage complications, and the oxygen tanks for the environmental control systems were only partially full.{{sfn|Press Kit|pp=10–11}}

== Flight ==
On January&nbsp;22, 1968, Apollo 5 lifted off from Launch Complex&nbsp;37B at Cape Kennedy Air Force Station<ref name= "legs" /> at 17:48:08 Eastern Standard Time (22:48:08 UTC).{{sfn|Orloff & Harland 2006|p=139}} The Saturn&nbsp;IB worked perfectly, inserting the second stage and LM into an {{convert|163|by|222|km|nmi|adj=on|sp=us|order=flip}} orbit.<ref name="orbital_info"/>{{efn|That is, a [[perigee]] of 163 km and an [[apogee]] of 222 km}} The nose cone was jettisoned, and after a coast of 43&nbsp;minutes 52&nbsp;seconds, the LM separated from its adapter, in a {{convert|167|by|222|km|nmi|order=flip|adj=on|sp=us}} orbit.<ref name="orbital_info"/>

After two orbits, the first planned 39-second descent-engine burn was started, but this was aborted after only four seconds by the [[Apollo Guidance Computer]], which detected that the spacecraft was not going as fast as expected. This happened because one of the engine's valves was suspected of being leaky and was not armed until it was time to ignite the engine, in orbit, which meant that the propellant took longer to reach the engine, leading to the lag. Programmers could have adjusted the software to account for this, but were not told. In addition, the tanks were only half full, and this contributed to the slowness of the ship. Had this occurred on a crewed mission, the astronauts would have been able to analyze the situation and decide whether the engine should be restarted.{{sfn|Brooks 1979|p=242}}<ref>
{{cite conference
   |url=http://www.doneyles.com/LM/Tales.html
   |title=Tales From The Lunar Module Guidance Computer
   |first=Don
   |last=Eyles
   |publisher=American Astronautical Society
   |date=February 6, 2004
   |work=27th annual Guidance and Control Conference
   |place=Breckenridge, Colorado}}</ref>

[[File:Robert R. Gilruth (right) and Christopher C. Kraft during Apollo 5.jpg|thumb|alt=Two middle-aged men sit at consoles, wearing headsets|Director of Flight Operations [[Christopher C. Kraft]] (left) and Manned Spaceflight Center director [[Robert R. Gilruth]] in Mission Control during Apollo 5]]

[[Gene Kranz]] was the flight director for Apollo&nbsp;5.{{sfn|Kranz 2000|p=215}} Mission Control, under Kranz's command, decided on a plan to conduct the engine and "fire-in-the-hole" tests under manual control. There were communication problems with the spacecraft, and omitting these tests would have meant the mission was a failure. Despite this, Kranz's team accomplished every burn.{{sfn|Kranz 2000|pp=218–220}} The ascent stage spun out of control eight hours into the mission, after completion of the engine burns, due to a problem with the guidance system.{{sfn|Orloff & Harland 2006|pp=142–143, 150}}

The stages were left in a low enough orbit that atmospheric drag would soon cause their orbits to decay and re-enter the atmosphere. The ascent stage re-entered on January&nbsp;24 and burned up; the descent stage re-entered on February&nbsp;12, falling into the Pacific several hundred miles southwest of [[Guam]].{{sfn|Orloff & Harland 2006|pp=142–144}}<ref>{{Cite book|title=Escaping the Bonds of Earth: The Fifties and the Sixties|last=Evans|first=Ben|publisher=Springer|year=2010|isbn=9780387790930|pages=435}}</ref> Simulations showed that the S-IVB stage of the launch vehicle (1968-007B) re-entered about 15.5&nbsp;hours into the flight.{{sfn|Orloff & Harland 2006|p=143}}

Apollo Spacecraft Program Manager [[George M. Low]] said that Apollo&nbsp;5's success "was due to the fact that we had a good piece of hardware; it was due to the fact that we had outstanding flight control teams under Gene Kranz' able leadership."<ref name = "legs" /> Despite the trouble during the descent-engine burn, [[NASA]] deemed the mission a success in demonstrating the LM systems, and a second uncrewed flight test using [[Apollo Lunar Module#Lunar modules produced|LM-2]] was cancelled.{{sfn|Orloff & Harland 2006|p=143}} The first crewed LM flight took place on [[Apollo 9]] in March 1969.{{sfn|Orloff & Harland 2006|p=223}}

==Notes==
{{notes}}

==References==
{{reflist}}

== Sources ==
* {{cite book|title=Apollo 5 Press Kit|publisher=NASA|location=Washington, D.C.|year=1968|url=https://uah.contentdm.oclc.org/digital/collection/p16608coll1/id/21351/|ref={{sfnRef|Press Kit}}|access-date=September 12, 2021|archive-date=January 25, 2022|archive-url=https://web.archive.org/web/20220125022212/https://uah.contentdm.oclc.org/digital/collection/p16608coll1/id/21351/|url-status=dead}}
* {{cite book|title=Astronautics and Aeronautics, 1967|publisher=NASA|location=Washington, D.C.|year=1968|url=https://history.nasa.gov/AAchronologies/1967.pdf|ref={{sfnRef|Astronautics 1967}}}}
* {{cite book |last1=Benson |first1=Charles D. |last2=Faherty |first2=William Barnaby |title=Moonport: A History of Apollo Launch Facilities and Operations|url=https://www.scribd.com/document/46301114/Moonport-a-History-of-Apollo-Launch-Facilities-and-Operations |year=1978 |publisher=NASA |id=NASA SP-4204}}
* {{cite book |last1=Brooks |first1=Courtney G. |last2=Grimwood |first2=James M. |last3=Swenson |first3=Loyd S. Jr. |title=Chariots for Apollo: A History of Manned Lunar Spacecraft |url=https://history.nasa.gov/SP-4205.pdf |series=NASA History Series |year=1979 |publisher=Scientific and Technical Information Office, NASA |location=Washington, D.C. |lccn=79001042 |id=NASA SP-4205|ref={{sfnRef|Brooks 1979}}}}
* {{Cite book |last1=Ertel |first1=Ivan D. |url=http://www.hq.nasa.gov/office/pao/History/SP-4009/contents.htm#Volume%20IV |title=The Apollo Spacecraft: A Chronology |last2=Newkirk |first2=Roland W. |last3=Brooks |first3=Courtney G. |publisher=NASA |year=1969–1978 |volume=IV |location=Washington, D.C. |lccn=69060008 |oclc=23818 |id=NASA SP-4009 |display-authors=2 |ref={{sfnRef|Ertel et al}} |access-date=September 11, 2021 |archive-date=February 5, 2008 |archive-url=https://web.archive.org/web/20080205020128/http://www.hq.nasa.gov/office/pao/History/SP-4009/contents.htm#Volume%20IV |url-status=dead }}
* {{cite book|year=2000|last=Kranz|first=Gene|title=Failure Is Not an Option: Mission Control from Mercury to Apollo 13 and Beyond|authorlink=Gene Kranz|location=New York|url=https://books.google.com/books?id=slQZ3JOUSKQC&pg=PA307|url-access=registration|publisher=Simon & Schuster|isbn=978-0-7432-0079-0|ref={{sfnRef|Kranz 2000}}}}
* {{cite book|last1=Orloff|first1=Richard W.|last2=Harland|first2=David M.|author-link2=David M. Harland|title=Apollo: The Definitive Sourcebook|year=2006|publisher=Praxis Publishing Company|location=Chichester, UK|isbn=978-0-387-30043-6|ref={{sfnRef|Orloff & Harland 2006}}}}

==External links==
{{Spoken Wikipedia|En-Apollo_5-article.ogg|date=2023-07-19}}
*[https://web.archive.org/web/20131006033925/https://usspaceobjectsregistry.state.gov/Pages/Home.aspx U.S. Registry of Objects Launched into Outer Space]
*{{Internet Archive short film | Apollo4Apollo5Missions | The Apollo 4 Mission and The Apollo 5 Mission}}

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