Editing Apollo 5 (section)

== 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}}