Editing Apollo 17 (section)

==== ALSEP ====
The [[Apollo Lunar Surface Experiments Package]] was a suite of nuclear-powered experiments, flown on each landing mission after Apollo 11. This equipment was to be emplaced by the astronauts to continue functioning after the astronauts returned to Earth.{{sfn|Orloff & Harland 2006|pp=601–602}} For Apollo 17, the ALSEP experiments were a [[Heat Flow Experiment]] (HFE), to measure the rate of heat flow from the interior of the Moon, a [[Lunar Surface Gravimeter]] (LSG), to measure alterations in the lunar gravity field at the site,{{sfn|Orloff 2004|loc=Statistical Tables: Lunar Surface Experiments}} a [[Lunar Atmospheric Composition Experiment]] (LACE), to investigate what the lunar atmosphere is made up of,<ref name="lace">{{cite web |title=Science Experiments – Lunar Atmospheric Composition |url=https://www.lpi.usra.edu/lunar/missions/apollo/apollo_17/experiments/lace/#:~:text=The%20Lunar%20Atmospheric%20Composition%20Experiment,by%20the%20Cold%20Cathode%20Gauge. |publisher=Lunar and Planetary Institute |access-date=February 8, 2022 |archive-date=July 9, 2021 |archive-url=https://web.archive.org/web/20210709143320/https://www.lpi.usra.edu/lunar/missions/apollo/apollo_17/experiments/lace/#:~:text=The%20Lunar%20Atmospheric%20Composition%20Experiment,by%20the%20Cold%20Cathode%20Gauge. |url-status=live }}</ref> a [[Lunar Seismic Profiling Experiment]] (LSPE), to detect nearby seismic activity, and a [[Lunar Ejecta and Meteorites Experiment]] (LEME), to measure the velocity and energy of dust particles.{{sfn|Orloff 2004|loc=Statistical Tables: Lunar Surface Experiments}} Of these, only the HFE had been flown before; the others were new.{{sfn|Orloff & Harland 2006|pp=601–602}}

The HFE had been flown on the aborted Apollo 13 mission, as well as on Apollo 15 and 16, but placed successfully only on Apollo 15, and unexpected results from that device made scientists anxious for a second successful emplacement. It was successfully deployed on Apollo 17.{{sfn|Chaikin 1995|pp=467–469, 478, 513}} The lunar gravimeter was intended to detect wavers in gravity, which would provide support for [[Albert Einstein]]'s [[general theory of relativity]];<ref>{{cite news |last1=Lunsford |first1=Christine |title=Apollo 17: NASA's Last Apollo Moon Landing Mission in Pictures |url=https://www.space.com/39006-apollo-17-moon-landing-mission-photos/2.html |access-date=February 8, 2022 |publisher=Space.com |date=December 7, 2017 |archive-date=February 8, 2022 |archive-url=https://web.archive.org/web/20220208025314/https://www.space.com/39006-apollo-17-moon-landing-mission-photos/2.html |url-status=live }}</ref> it ultimately failed to function as intended.<ref name="alsjtge"/> The LACE was a surface-deployed module that used a [[mass spectrometer]] to analyze the Moon's atmosphere.<ref>{{cite report |last1=Stern |first1=S. Alan |title=The Lunar Atmosphere: History, Status, Current Problems, and Context |year=1999 |publisher=Southwest Research Institute |citeseerx=10.1.1.21.9994 }}</ref> On previous missions, the [[Cold Cathode Gauge Experiment|Code Cathode Gauge]] experiment had measured the quantity of atmospheric particles, but the LACE determined which gases were present: principally neon, helium and hydrogen.<ref name="lace"/> The LSPE was a seismic-detecting device that used [[geophone]]s, which would detect explosives to be set off by ground command once the astronauts left the Moon.{{sfn|Orloff 2004|loc=Statistical Tables: Lunar Surface Experiments}} When operating, it could only send useful data to Earth in high bit rate, meaning that no other ALSEP experiment could send data then, and limiting its operating time. It was turned on to detect the liftoff of the ascent stage, as well as use of the explosives packages, and the ascent stage's impact, and thereafter about once a week, as well as for some 100 hour periods.<ref>{{cite web |title=Lunar Seismic Profiling Experiment |url=https://www.lpi.usra.edu/lunar/missions/apollo/apollo_17/experiments/lspe/Apollo-17-active-seismic-NSSDCA.pdf |archive-url=https://ghostarchive.org/archive/20221009/https://www.lpi.usra.edu/lunar/missions/apollo/apollo_17/experiments/lspe/Apollo-17-active-seismic-NSSDCA.pdf |archive-date=2022-10-09 |url-status=live|publisher=Lunar and Planetary Institute}}</ref> The LEME had a set of detectors to measure the characteristics of the dust particles it sought.{{sfn|Orloff 2004|loc=Statistical Tables: Lunar Surface Experiments}} It was hoped that the LEME would detect dust impacting the Moon from elsewhere, such as from comets or interstellar space, but analysis showed that it primarily detected dust moving at slow speeds across the lunar surface.<ref name="leme">{{cite web |title=Science Experiments – Lunar Ejecta and Meteorite |url=https://www.lpi.usra.edu/lunar/missions/apollo/apollo_17/experiments/lem/ |publisher=Lunar and Planetary Institute |access-date=February 12, 2022 |archive-date=January 20, 2022 |archive-url=https://web.archive.org/web/20220120031105/https://www.lpi.usra.edu/lunar/missions/apollo/apollo_17/experiments/lem/ |url-status=live }}</ref>

All powered ALSEP experiments that remained active were deactivated on September 30, 1977,{{sfn|Orloff & Harland 2006|pp=601–602}} principally because of budgetary constraints.<ref name="astro">{{cite news|newspaper=[[Astronomy (magazine)|Astronomy]]|access-date=February 1, 2021|title=What did the Apollo astronauts leave behind?|date=June 21, 2019|last=Talcott|first=Richard|url=https://astronomy.com/news/2019/06/what-did-the-apollo-astronauts-leave-behind|archive-date=February 1, 2022|archive-url=https://web.archive.org/web/20220201050005/https://astronomy.com/news/2019/06/what-did-the-apollo-astronauts-leave-behind|url-status=live}}</ref>