Editing Apollo 8 (section)

===Lunar trajectory===

Lovell's main job as Command Module Pilot was as [[flight officer|navigator]]. Although Mission Control normally performed all the navigation calculations, it was necessary to have a crew member adept at navigation so that the crew could return to Earth in case communication with Mission Control was lost. Lovell navigated by star sightings using a [[sextant]] built into the spacecraft, measuring the angle between a star and the Earth's (or the Moon's) [[horizon]]. This task was made difficult by a large cloud of debris around the spacecraft, which made it hard to distinguish the stars.<ref name="journal day 1 green">{{cite web |url=http://history.nasa.gov/ap08fj/03day1_green_sep.htm |title=Day 1: Green Team |last1=Woods |first1=W. David |last2=O'Brien |first2=Frank |date=April 22, 2006 |work=Apollo 8 Flight Journal |publisher=NASA |access-date=January 30, 2008 |archive-url=https://web.archive.org/web/20080114013205/http://history.nasa.gov/ap08fj/03day1_green_sep.htm |archive-date=January 14, 2008 |url-status=dead  }}</ref>

By seven hours into the mission, the crew was about 1{{nbsp}}hour and 40 minutes behind flight plan because of the problems in moving away from the S-IVB and Lovell's obscured star sightings. The crew placed the spacecraft into Passive Thermal Control (PTC), also called "barbecue roll", in which the spacecraft rotated about once per hour around its long axis to ensure even heat distribution across the surface of the spacecraft. In direct sunlight, parts of the spacecraft's outer surface could be heated to over {{convert|200|C|F}}, while the parts in shadow would be {{convert|-100|C|F}}. These temperatures could cause the [[atmospheric reentry#Thermal protection systems|heat shield]] to crack and propellant lines to burst. Because it was impossible to get a perfect roll, the spacecraft swept out a [[Conical surface|cone]] as it rotated. The crew had to make minor adjustments every half hour as the cone pattern got larger and larger.<ref name="journal day 1 Maroon">{{cite web|url=https://history.nasa.gov/ap08fj/04day1_maroon.htm |title=Day 1: Maroon Team |last1=Woods |first1=W. David |last2=O'Brien |first2=Frank |work=Apollo 8 Flight Journal |publisher=NASA |date=April 22, 2006 |access-date=February 4, 2008 |archive-url=https://web.archive.org/web/20080107002315/https://history.nasa.gov/ap08fj/04day1_maroon.htm |archive-date=January 7, 2008 |url-status=dead}}</ref>
[[File:AS08-16-2593 remastered.jpg|thumb|left|The [[first images of Earth from space|first image taken by humans of the whole Earth]], probably photographed by [[William Anders]].<ref name="journal day 1 green"/> (time tag:  003:42:55) South America is visible in the lower half.]]

The first mid-course correction came eleven hours into the flight. The crew had been awake for more than 16 hours. Before launch, NASA had decided at least one crew member should be awake at all times to deal with problems that might arise. Borman started the first sleep shift but found sleeping difficult because of the constant radio chatter and mechanical noises. Testing on the ground had shown that the [[Apollo command and service module#Service propulsion system|service propulsion system]] (SPS) engine had a small chance of exploding when burned for long periods unless its [[combustion chamber]] was "coated" first by burning the engine for a short period. This first correction burn was only 2.4 seconds and added about {{convert|20.4|ft/s|m/s|abbr=on|sp=us}} velocity [[Retrograde and prograde motion|prograde]] (in the direction of travel).{{sfn|Orloff|2000|p=35}} This change was less than the planned {{convert|24.8|ft/s|m/s|abbr=on|sp=us}}, because of a bubble of [[helium]] in the [[nitrogen tetroxide|oxidizer]] lines, which caused unexpectedly low propellant pressure. The crew had to use the small RCS thrusters to make up the shortfall. Two later planned mid-course corrections were canceled because the Apollo{{nbsp}}8 trajectory was found to be perfect.<ref name="journal day 1 Maroon"/>

About an hour after starting his sleep shift, Borman obtained permission from [[flight controller|ground control]] to take a [[Secobarbital|Seconal]] [[Barbiturate|sleeping pill]]. The pill had little effect. Borman eventually fell asleep, and then awoke feeling ill. He vomited twice and had a bout of diarrhea; this left the spacecraft full of small globules of vomit and feces, which the crew cleaned up as well as they could. Borman initially did not want everyone to know about his medical problems, but Lovell and Anders wanted to inform Mission Control. The crew decided to use the Data Storage Equipment (DSE), which could tape voice recordings and telemetry and dump them to Mission Control at high speed. After recording a description of Borman's illness they asked Mission Control to check the recording, stating that they "would like an evaluation of the voice comments".<ref name="journal day 2 green">{{cite web |url=https://history.nasa.gov/ap08fj/06day2_green.htm |title=Day 2: Green Team |last1=Woods |first1=W. David |last2=O'Brien |first2=Frank |date=April 22, 2006 |work=Apollo 8 Flight Journal |publisher=NASA |access-date=January 30, 2008 |archive-url=https://web.archive.org/web/20080311114001/https://history.nasa.gov/ap08fj/06day2_green.htm |archive-date=March 11, 2008 |url-status=dead }}</ref>

The Apollo 8 crew and Mission Control medical personnel held a conference using an unoccupied second-floor control room (there were two identical control rooms in Houston, on the second and third floors, only one of which was used during a mission). The conference participants concluded that there was little to worry about and that Borman's illness was either a [[Gastroenteritis|24-hour flu]], as Borman thought, or a reaction to the sleeping pill.{{sfn|Collins|2001|p=306}} Researchers now believe that he was suffering from [[space adaptation syndrome]], which affects about a third of astronauts during their first day in space as their [[Labyrinth (inner ear)|vestibular system]] adapts to [[weightlessness]].<ref>{{cite journal |last=Quine |first=Tony |date=April 2007|title=Addicted to space: An appreciation of Anousheh Ansari, Part II |journal= Spaceflight|volume=49 |issue=4 |page=144|issn=0038-6340 |publisher=[[British Interplanetary Society]]}}</ref> Space adaptation syndrome had not occurred on previous spacecraft ([[Project Mercury|Mercury]] and [[Project Gemini|Gemini]]), because those astronauts could not move freely in the small cabins of those spacecraft. The increased cabin space in the Apollo command module afforded astronauts greater freedom of movement, contributing to symptoms of space sickness for Borman and, later, astronaut [[Rusty Schweickart]] during Apollo{{nbsp}}9.<ref>{{cite web |url=http://lsda.jsc.nasa.gov/scripts/experiment/exper.aspx?exp_index=747 |title=The Effects of Long-Duration Space Flight on Eye, Head, and Trunk Coordination During Locomotion |last1=Kozlovskaya |first1=Inessa B |last2=Bloomberg |first2=Jacob J. |last3=Layne |first3=Charles S. |year=2004 |work=Life Sciences Data Archive |publisher=Lyndon B. Johnson Space Center |id=LSDA Exp ID: 9307191 |access-date=June 28, 2013 |display-authors=2}}</ref>
[[File:Ap8-S68-56531.jpg|thumb|right|Still from film of the crew taken while they were in orbit around the Moon. Frank Borman is in the center.]]

The cruise phase was a relatively uneventful part of the flight, except for the crew's checking that the spacecraft was in working order and that they were on course. During this time, NASA scheduled a television broadcast at 31 hours after launch. The Apollo{{nbsp}}8 crew used a {{convert|2|kg|lb|adj=on}} camera that broadcast in [[black-and-white]] only, using a [[Video camera tube|Vidicon]] tube. The camera had two [[lens (optics)|lenses]], a very [[wide-angle lens|wide-angle (160°) lens]], and a [[telephoto lens|telephoto (9°) lens]].{{sfn|Orloff|2000|p=36}}<ref name="journal day 2 Maroon">{{cite web|url=http://history.nasa.gov:80/ap08fj/07day2_maroon.htm |title=Day 2: Maroon Team |last1=Woods |first1=W. David |last2=O'Brien |first2=Frank |work=Apollo 8 Flight Journal |publisher=NASA |date=April 22, 2006 |access-date=February 4, 2008 |archive-url=https://web.archive.org/web/20080404232523/http://history.nasa.gov/ap08fj/07day2_maroon.htm |archive-date=April 4, 2008 |url-status=dead}}</ref>

During this first broadcast, the crew gave a tour of the spacecraft and attempted to show how the Earth appeared from space. However, difficulties aiming the narrow-angle lens without the aid of a monitor to show what it was looking at made showing the Earth impossible. Additionally, without proper [[Optical filter|filters]], the Earth image became saturated by any bright source. In the end, all the crew could show the people watching back on Earth was a bright blob.{{sfn|Orloff|2000|p=36}} After broadcasting for 17 minutes, the rotation of the spacecraft took the [[high-gain antenna]] out of view of the receiving stations on Earth and they ended the transmission with Lovell wishing his mother a happy birthday.<ref name="journal day 2 Maroon" />

By this time, the crew had completely abandoned the planned sleep shifts. Lovell went to sleep {{frac|32|1|2}} hours into the flight&nbsp;– three-and-a-half hours before he had planned to. A short while later, Anders also went to sleep after taking a sleeping pill.<ref name="journal day 2 Maroon" /> The crew was unable to see the Moon for much of the outward cruise. Two factors made the Moon almost impossible to see from inside the spacecraft: three of the five windows fogging up due to out-gassed oils from the [[silicone]] [[sealant]], and the [[Orientation (geometry)|attitude]] required for passive thermal control. It was not until the crew had gone behind the Moon that they would be able to see it for the first time.{{sfn|Brooks|Grimwood|Swenson|1979|p=277}}

Apollo 8 made a second television broadcast at 55 hours into the flight. This time, the crew rigged up filters meant for the still cameras so they could acquire images of the Earth through the telephoto lens. Although difficult to aim, as they had to maneuver the entire spacecraft, the crew was able to broadcast back to Earth the first television pictures of the Earth. The crew spent the transmission describing the Earth, what was visible, and the colors they could see. The transmission lasted 23 minutes.{{sfn|Orloff|2000|p=36}}