Editing Apollo 9 (section)

=== Sixth through eleventh days (March 8–13) ===
[[File:Apollo 9 approaches splashdown.jpg|thumb|left|alt=Spaceship descends over ocean with parachutes|Apollo 9 approaches [[splashdown (spacecraft landing)|splashdown]] in the [[Atlantic Ocean]], March 13, 1969]]

Apollo 9 was to remain in space for about ten days to check how the CSM would perform over the period of time required for a lunar mission.{{sfn|French & Burgess|p=352}} Most major events had been scheduled for the first days so that they would be accomplished if the flight needed to be ended early.{{sfn|Orloff & Harland|p=223}} The remaining days in orbit were to be conducted at a more leisurely pace.{{sfn|Press Kit|pp=2, 6}} With the main goals of the mission accomplished, the hatch window was used for special photography of Earth, using four identical [[Hasselblad]] cameras, coupled together and using film sensitive to different parts of the [[electromagnetic spectrum]].<ref name=nasa>{{cite book|editor-last=Nicks|editor-first=Oran W.|title=This Island Earth|publisher=[[NASA]]|year=1970|pages=100–101}}</ref> Such photography allowed different features of the Earth's surface to appear, for example, tracking of water pollution as it exits mouths of rivers into the sea,{{sfn|''Science News'' 1969-03-15|p=255}} and the highlighting of agricultural areas using [[infrared]].<ref name=nasa/> The camera system was a prototype, and would pave the way for the [[Earth Resources Technology Satellite]], predecessor to the [[Landsat]] series.{{sfn|Harland|p=335}} The photography was successful, as the ample time in orbit meant the crew could wait to allow cloud cover to pass, and would inform [[Skylab]]'s mission planning.{{sfn|Orloff & Harland|p=230}}

Scott used a [[sextant]] to track landmarks on the Earth, and turned the instrument to the skies to observe the planet Jupiter, practicing navigation techniques that were to be used on later missions.<ref name = "NYT March 10">{{cite news|last=Wilford|first=John Noble|author-link=John Noble Wilford|url=https://www.nytimes.com/1969/03/10/archives/the-apollo-9-astronauts-take-a-restful-cruise-through-space.html|title=The Apollo 9 astronauts take a restful cruise through space|date=March 10, 1969|newspaper=[[The New York Times]]|page=40|url-access=subscription}}</ref> The crew was able to track the [[Pegasus 3]] satellite (launched in 1965) as well as the ascent stage of ''Spider''.{{sfn|Orloff & Harland|p=230}} The sixth burn of the SPS engine took place on the sixth day, though it was postponed one orbit as the [[reaction control system]] (RCS) thruster burn needed to [[Ullage#Rocketry|settle the reactants in their tanks]] was not properly programmed. The SPS burn lowered the perigee of Apollo{{nbsp}}9's orbit,{{sfn|Mission Report|p=3-2}} allowing for improved RCS thruster deorbit capability as a backup to the SPS.{{sfn|Press Kit|pp=6, 22}}

[[File:The Apollo 9 Command Module (CM).jpg|thumb|right|alt=A spacecraft is lifted in the air onto a ship|''Gumdrop'' is hoisted aboard the USS ''Guadalcanal'']]

Considerable testing of the CSM took place, but this was principally Scott's responsibility, allowing McDivitt and Schweickart leisure to observe the Earth; they alerted Scott if anything particularly noteworthy was upcoming, letting him leave his work for a moment to look at Earth too.{{sfn|French & Burgess|pp=352–353}} The seventh burn of the SPS system took place on the eighth day, March 10; its purpose was again to aid RCS deorbit capability, as well as extending ''Gumdrop''{{'s}} orbital lifetime. It shifted the apogee of the orbit to the Southern Hemisphere, allowing for a longer free-fall time to entry when Apollo{{nbsp}}9 returned to Earth. The burn was extended to allow for testing of the propellent gaging system, which had been behaving anomalously during earlier SPS burns.{{sfn|Mission Report|p=3-2}}{{sfn|Press Kit|p=22}} Once it was accomplished, Apollo{{nbsp}}9's RCS thrusters could have returned it to Earth and still allowed it to land in the primary recovery zone had the SPS engine failed. The eighth and final SPS burn, to return the vehicle to Earth, was accomplished on March&nbsp;13, less than an hour after the ten-day mark of the mission, after which the service module was jettisoned. The landing was delayed one orbit because of unfavorable weather in the primary landing zone{{sfn|Mission Report|p=7-4}} some {{convert|220|nmi}} ESE of Bermuda.{{sfn|Press Kit|p=7}}<ref name=clss>{{cite news |url=https://news.google.com/newspapers?id=9GxYAAAAIBAJ&sjid=EvgDAAAAIBAJ&pg=6683%2C3180989 |work=Spokane Daily Chronicle |location=(Washington) |agency=Associated Press |title=Capsule's landing sight shifted |date=March 12, 1969 |page=1}}</ref><ref name=mapsite>{{cite news |url=https://news.google.com/newspapers?id=9GxYAAAAIBAJ&sjid=EvgDAAAAIBAJ&pg=5651%2C3217879 |work=Spokane Daily Chronicle |location=(Washington) |agency=AP map |title=Splashdown sites |date=March 12, 1969 |page=2}}</ref> Instead, Apollo{{nbsp}}9 splashed down {{convert|160|nmi}} east of the Bahamas, about {{convert|3|mi}} from the recovery carrier, the [[USS Guadalcanal (LPH-7)|USS ''Guadalcanal'']],{{sfn|French & Burgess|p=353}} after a mission lasting 10 days, 1{{nbsp}}hour, 54 seconds.{{sfn|Mission Report|p=1-2}} Apollo{{nbsp}}9 was the last spacecraft to splash down in the Atlantic Ocean for a half century, until the [[Crew Dragon Demo-1]] mission in 2019,<ref>{{cite web|publisher=[[NASA]]|title=Crew Dragon splashes down in Atlantic ending first commercial crew mission|last=Moran|first=Norah|date=March 8, 2019|access-date=April 17, 2019|url=https://blogs.nasa.gov/spacestation/2019/03/08/crew-dragon-splashes-down-in-atlantic-ending-first-commercial-crew-mission/}}</ref><ref name=sleaf>{{cite news |url=https://news.google.com/newspapers?id=9WxYAAAAIBAJ&sjid=EvgDAAAAIBAJ&pg=7360%2C3565458 |work=Spokane Daily Chronicle |location=(Washington) |agency=Associated Press |title=Safe landing ends Apollo flight |date=March 13, 1969 |page=1}}</ref> and last crewed splashdown in the Atlantic until [[Inspiration4]] in 2021.<ref>{{cite news |title=SpaceX Inspiration4 crew returns to Earth in Atlantic Ocean splashdown |url=https://www.today.com/news/spacex-inspiration4-crew-makes-splashdown-atlantic-ocean-t231570 |access-date=September 18, 2021 |agency=Associated Press |date=September 18, 2021 |language=en}}</ref>