Editing Apollo 13 (section)

===Launch and translunar injection===
[[File:Apollo 13 launch (S70-34852).jpg|thumb|upright|Apollo&nbsp;13 launches from Kennedy Space Center, April 11, 1970]]
[[File:Apolo-1. CSM&LM diagram.svg|thumb|Apollo 13 spacecraft configuration during most of the journey: Click on image for key to numbered components.]]
The mission was launched at the planned time, 2:13:00&nbsp;pm [[Eastern Time Zone|EST]] (19:13:00&nbsp;UTC) on April 11. An anomaly occurred when the second-stage, center (inboard) engine shut down about two minutes early.<ref name="lver">{{cite book |author= |url=https://archive.org/details/nasa_techdoc_19900066486 |title=Saturn 5 Launch Vehicle Flight Evaluation Report: AS-508 Apollo 13 Mission |date=June 20, 1970 |publisher=[[NASA]] |publication-place=[[Marshall Space Flight Center|George C. Marshall Space Flight Center]], Huntsville, Alabama |id=MPR-SAT-FE-70-2 |access-date=May 30, 2017}}</ref>{{sfn|Benson & Faherty|1979|pp=494–499}} This was caused by severe [[pogo oscillation]]s. Starting with Apollo 10, the vehicle's guidance system was designed to shut the engine down in response to chamber pressure excursions.{{sfn|Larsen|2008|p=5-13}} Pogo oscillations had occurred on [[Titan (rocket family)|Titan rockets]] (used during the [[Project Gemini|Gemini program]]) and on previous Apollo missions,<ref>{{cite journal|last=Fenwick |first=Jim |date=Spring 1992 |title=Pogo |url=http://www.engineeringatboeing.com/articles/pogo.htm |journal=Threshold |publisher=[[Pratt & Whitney Rocketdyne]] |access-date=July 3, 2013 |url-status=dead |archive-url=https://web.archive.org/web/20071213010936/http://www.engineeringatboeing.com/articles/pogo.htm |archive-date=December 13, 2007 }}</ref>{{sfn|Larsen|2008|pp=5-7–5-12}} but on Apollo&nbsp;13 they were amplified by an interaction with turbopump [[cavitation]].<ref>{{cite journal |last=Dotson |first=Kirk |date=Winter 2003–2004 |title=Mitigating Pogo on Liquid-Fueled Rockets |journal=Crosslink |volume=5 |issue=1 |pages=26–29 |location=El Segundo, California|publisher=[[The Aerospace Corporation]] |access-date=July 3, 2013 |url=http://aerospace.wpengine.netdna-cdn.com/wp-content/uploads/crosslink/V5N1.pdf |archive-url=https://ghostarchive.org/archive/20221009/http://aerospace.wpengine.netdna-cdn.com/wp-content/uploads/crosslink/V5N1.pdf |archive-date=2022-10-09 |url-status=live}}</ref><ref name=launch>{{cite web |url=https://history.nasa.gov/afj/ap13fj/01launch_ascent.html |title=Launch and Reaching Earth Orbit |year=2016 |editor-last=Woods |editor-first=W. David |editor-last2=Turhanov|editor-first2=Alexandr|editor-last3=Waugh|editor-first3=Lennox J. |work=Apollo 13 Flight Journal |publisher=NASA |access-date=August 5, 2019}}</ref> A fix to prevent pogo was ready for the mission, but schedule pressure did not permit the hardware's integration into the Apollo&nbsp;13 vehicle.{{sfn|Larsen|2008|p=5-13}}<ref>{{cite journal|url=https://www.universetoday.com/62672/13-things-that-saved-apollo-13-part-5-unexplained-shutdown-of-the-saturn-v-center-engine/|last=Atkinson|first=Nancy|title=13 things that saved Apollo 13, Part 5: Unexplained shutdown of the Saturn V center engine|date=April 14, 2010|journal=[[Universe Today]]|access-date=September 16, 2019}}</ref> A post-flight investigation revealed the engine was one cycle away from catastrophic failure.{{sfn|Larsen|2008|p=5-13}} The four outboard engines and the [[S-IVB]] third stage burned longer to compensate, and the vehicle achieved very close to the planned circular {{convert|190|km|mi nmi|sp=us}} [[parking orbit]], followed by a translunar injection (TLI) about two hours later, setting the mission on course for the Moon.<ref name="lver" />{{sfn|Benson & Faherty|1979|pp=494–499}}

After TLI, Swigert performed the separation and transposition maneuvers before docking the CSM ''Odyssey'' to the LM ''Aquarius'', and the spacecraft pulled away from the third stage.<ref name = "journal extraction">{{cite web|work=Apollo Lunar Flight Journal|url=https://history.nasa.gov/afj/ap13fj/03tde.html|title=Day 1: Transposition, Docking and Extraction|date=February 17, 2017|access-date=August 12, 2019|last1=Woods|first1=W. David |last2=Kemppanen |first2=Johannes|last3=Turhanov|first3=Alexander|last4=Waugh |first4=Lennox J.}}</ref> Ground controllers then sent the third stage on a course to impact the Moon in range of the Apollo 12 seismometer, which it did just over three days into the mission.{{sfn|Orloff & Harland|2006|p=367}}

The crew settled in for the three-day trip to Fra Mauro. At 30:40:50 into the mission, with the TV camera running, the crew performed a burn to place Apollo&nbsp;13 on a hybrid trajectory. The departure from a [[free-return trajectory]] meant that if no further burns were performed, Apollo&nbsp;13 would miss Earth on its return trajectory, rather than intercept it, as with a free return.<ref name = "journal midcourse">{{cite web|work=Apollo Lunar Flight Journal|url=https://history.nasa.gov/afj/ap13fj/05day2-mcc2-tv.html|title=Day 2: Midcourse correction 2 on TV|date=February 17, 2017|access-date=August 7, 2019}}</ref> A free return trajectory could only reach sites near the lunar equator; a hybrid trajectory, which could be started at any point after TLI, allowed sites with higher latitudes, such as Fra Mauro, to be reached.<ref name = "journal hybrid">{{cite web|work=Apollo Lunar Flight Journal|url=https://history.nasa.gov/afj/launchwindow/lw1.html|title=Apollo lunar landing launch window: The controlling factors and constraints|year=2009|access-date=December 2, 2019|author=Robin Wheeler}}</ref> Communications were enlivened when Swigert realized that in the last-minute rush, he had omitted to file his [[Form 1040|federal income tax return]] (due April 15), and amid laughter from mission controllers, asked how he could get an extension. He was found to be entitled to a 60-day extension for being out of the country at the deadline.{{sfn|NASA 1970|p=8}}

Entry into the LM to test its systems had been scheduled for 58:00:00; when the crew awoke on the third day of the mission, they were informed it had been moved up three hours and was later moved up again by another hour. A television broadcast was scheduled for 55:00:00; Lovell, acting as emcee, showed the audience the interiors of ''Odyssey'' and ''Aquarius''.<ref name=storm>{{cite web |url=https://history.nasa.gov/afj/ap13fj/07day3-before-the-storm.html |title=Day 3: Before the storm |year=2016 |editor-last=Woods |editor-first=W. David |editor-last2=Turhanov|editor-first2=Alexandr|editor-last3=Waugh|editor-first3=Lennox J. |work=Apollo 13 Flight Journal |publisher=NASA |access-date=August 27, 2019}}</ref> The audience was limited since none of the television networks were carrying the broadcast,{{sfn|Houston, Heflin & Aaron|2015|p=206}} forcing Marilyn Lovell (Jim Lovell's wife) to go to the VIP room at Mission Control if she wanted to watch her husband and his crewmates.{{sfn|Chaikin|1995|pp=285–287}}
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