Editing Apollo 17 (section)

=== Launch and outbound trip ===
[[File:Apollo 17 liftoff.jpg|thumb|right|Apollo 17 launches on December 7, 1972]]

Originally planned to launch on December 6, 1972, at 9:53&nbsp;p.m. [[Eastern Standard Time (North America)|EST]] (2:53&nbsp;a.m. on December 7 UTC),{{sfn|Orloff & Harland 2006|p=510}} Apollo 17 was the final crewed Saturn{{nbsp}}V launch, and the only one to occur at night. The launch was delayed by two hours and forty minutes due to an automatic cutoff in the launch sequencer at the T−30 second mark in the countdown. The cause of the problem was quickly determined to be the launch sequencer's failure to automatically pressurize the liquid oxygen tank in the third stage of the rocket; although launch control noticed this and manually caused the tank to pressurize, the sequencer did not recognize the fix and therefore paused the countdown. The clock was reset and held at the T−22 minute mark while technicians worked around the malfunction in order to continue with the launch. This pause was the only launch delay in the Apollo program caused by a hardware problem. The countdown then resumed, and the liftoff occurred at 12:33&nbsp;a.m. EST on December 7, 1972.<ref name=astronautix/><ref name=launchops>{{cite web|title=Apollo 17 Launch Operations|url=http://www.hq.nasa.gov/office/pao/History/SP-4204/ch23-7.html|publisher=NASA|access-date=November 16, 2011|archive-date=October 27, 2011|archive-url=https://web.archive.org/web/20111027162938/http://www.hq.nasa.gov/office/pao/History/SP-4204/ch23-7.html|url-status=live}}</ref> The launch window, which had begun at the originally planned launch time of 9:53&nbsp;p.m. on December 6, remained open until 1:31&nbsp;a.m., the latest time at which a launch could have occurred during the December 6–7 window.{{sfn|Orloff 2004|loc=Statistical Tables: Launch Windows}}

Approximately 500,000 people observed the launch in the immediate vicinity of Kennedy Space Center, despite the early-morning hour. The launch was visible as far away as {{convert|800|km|mi nmi|abbr=on}}, and observers in [[Miami|Miami, Florida]], reported a "red streak" crossing the northern sky.<ref name=launchops/> Among those in attendance at the program's final launch were astronauts [[Neil Armstrong]] and Dick Gordon, as well as centenarian [[Charlie Smith (centenarian)|Charlie Smith]], who alleged he was 130 years old at the time of Apollo 17.{{sfn|Chaikin 1995|pp=495, 498}}

The ascent resulted in an orbit with an altitude and velocity almost exactly that which had been planned.{{sfn|Orloff & Harland 2006|p=511}} In the hours following the launch, Apollo 17 orbited the Earth while the crew spent time monitoring and checking the spacecraft to ensure its readiness to depart Earth orbit. At 3:46&nbsp;a.m. EST, the S-IVB third stage was reignited for the 351-second [[trans-lunar injection]] burn to propel the spacecraft towards the Moon.<ref name="a17pre"/><ref name=astronautix>{{cite web|last=Wade|first=Mark|title=Apollo 17|url=http://www.astronautix.com/flights/apollo17.htm|publisher=Encyclopedia Astronautica|access-date=August 22, 2011|url-status=dead|archive-url=https://web.archive.org/web/20110812193502/http://www.astronautix.com/flights/apollo17.htm|archive-date=August 12, 2011}}</ref> Ground controllers chose a faster trajectory for Apollo 17 than originally planned to allow the vehicle to reach lunar orbit at the planned time, despite the launch delay.{{sfn|Orloff & Harland 2006|p=514}} The Command and Service Module separated from the S-IVB approximately half an hour following the S-IVB trans-lunar injection burn, after which Evans turned the spacecraft to face the LM, still attached to the S-IVB. The CSM then docked with the LM and extracted it from the S-IVB. Following the LM extraction, Mission Control programmed the S-IVB, no longer needed to propel the spacecraft, to impact the Moon and trip the seismometers left by prior Apollo crews.<ref name="a17pre"/> It struck the Moon just under 87 hours into the mission, triggering the seismometers from Apollo 12, 14, 15 and 16.{{sfn|Orloff & Harland 2006|p=214}} Approximately nine hours after launch, the crew concluded the mission's first day with a sleep period, until waking up to begin the second day.<ref name="a17pre"/>

[[File:The Earth seen from Apollo 17.jpg|thumb|upright=1.2|left|View of Earth from Apollo 17 while in transit to the Moon, a photo now known as ''[[The Blue Marble]]'']]
Mission Control and the crew decided to shorten the mission's second day, the first full day in space, in order to adjust the crew's wake-up times for the subsequent days in preparation for an early morning (EST) wake-up time on the day of the lunar landing, then scheduled for early afternoon (EST). This was done since the first day of the mission had been extended because of the launch delay. Following the second rest period, and on the third day of the mission, the crew executed the first mid-course correction, a two-second burn of the CSM's service propulsion engine to adjust the spacecraft's Moon-bound trajectory. Following the burn, the crew opened the hatch separating the CSM and LM in order to check the LM's systems and concluded that they were nominal.<ref name="a17pre"/> So that events would take place at the time indicated in the flight plan, the mission clocks were moved ahead by 2 hours and 40 minutes, the amount of the launch delay, with one hour of it at 45:00:00 into the mission and the remainder at 65:00:00.<ref name="jump">{{cite web|title=Day 4, part 1: Clock update|date=December 26, 2017|access-date=November 24, 2021|editor-first=David|editor-last=Woods|editor2-first=Ben|editor2-last=Feist|publisher=NASA|url=https://history.nasa.gov/afj/ap17fj/09_day04_part1_clock_update.html|work=Apollo 17 Flight Journal|archive-date=July 21, 2019|archive-url=https://web.archive.org/web/20190721143515/https://history.nasa.gov/afj/ap17fj/09_day04_part1_clock_update.html|url-status=live}}</ref>

Among their other activities during the outbound trip, the crew photographed the Earth from the spacecraft as it travelled towards the Moon. One of these photographs is now known as ''[[The Blue Marble]]''.<ref>{{cite magazine |url=https://time.com/3879555/blue-marble-apollo-17-photo-of-earth-from-space/ |title=Home, Sweet Home: In Praise of Apollo 17's 'Blue Marble' |last=Cosgrove |first=Ben |magazine=[[Time (magazine)|Time]] |date=April 11, 2014 |access-date=December 7, 2019 |url-status=dead |archive-url=https://web.archive.org/web/20150601092710/https://time.com/3879555/blue-marble-apollo-17-photo-of-earth-from-space/ |archive-date=June 1, 2015}}</ref> The crew found that one of the latches holding the CSM and LM together was unlatched. While Schmitt and Cernan were engaged in a second period of LM housekeeping beginning just before sixty hours into the Mission, Evans worked on the balky latch. He was successful, and left it in the position it would need to be in for the CSM-LM docking that would occur upon return from the lunar surface.{{sfn|Orloff & Harland 2006|pp=514–515}}

Also during the outward journey, the crew performed a heat flow and convection demonstration, as well as the Apollo light-flash experiment. A few hours before entry into lunar orbit, the SIM door on the SM was jettisoned. At approximately 2:47&nbsp;p.m. EST on December 10, the [[service propulsion system]] engine on the CSM ignited to slow down the CSM/LM stack into lunar orbit. Following orbit insertion and orbital stabilization, the crew began preparations for the landing at Taurus–Littrow.<ref name=astronautix/>