Editing Apollo 9 (section)

=== Life Support System backpack ===
[[File:Apollo 9 Schweickart with EMU.jpg|upright|thumb|alt=Spacesuited man with large backpack|Schweickart with the life support backpack]]

The [[Apollo/Skylab A7L|Extravehicular Mobility Unit]] (EMU) backpack flew for the first time on Apollo{{nbsp}}9, used by Schweickart during his EVA.<ref name="sp368ch6">[[#sp368|Carson et al. 1975]]</ref> This included the [[Portable Life Support System]] (PLSS), providing oxygen to the astronaut and water for the [[Liquid Cooling Garment]] (LCG), which helped prevent overheating during extravehicular activity.{{sfn|Press Kit|pp=84–85}} Also present was the [[Oxygen Purge System]] (OPS), the "bedroll" atop the backpack, which could provide oxygen for up to roughly an hour if the PLSS failed.{{sfn|Thomas|p=22}} A more advanced version of the EMU was used for the lunar landing on Apollo 11.{{sfn|Thomas|p=22}}

During his stand-up EVA,{{efn|A stand-up EVA is when the astronaut only partially exits the spacecraft.<ref>{{cite web|url=http://planet4589.org/space/jsr/back/news.601.txt|title=Shuttle and Station|date=October 12, 2008|access-date=April 29, 2019|publisher=Jonathan's Space Report}}</ref>{{sfn|Thomas|McMann|p=68}}}} Scott did not wear a PLSS, but was connected to the CM's life support systems through an umbilical, utilizing a Pressure Control Valve (PCV). This device had been created in 1967 to allow for stand-up EVAs from the hatches of the LM or CM, or for brief ventures outside. It was later used by Scott for his lunar surface stand-up EVA on [[Apollo 15]], and for the deep-space EVAs by the command module pilots of the final three Apollo flights.{{sfn|Thomas|pp=24–25}}