Editing Apollo 17 (section)

==== Other lunar-surface science ====
[[File:Apollo 17 rover at final resting site.jpg|thumb|Apollo 17's [[Lunar Roving Vehicle]]. The Surface Electrical Properties (SEP) experiment receiver is the antenna on the right-rear of the vehicle|alt=Black and white photo of a lunar rover with a lunar landing module in the background.]]Like Apollo 15 and 16, Apollo 17 carried a Lunar Roving Vehicle. In addition to being used by the astronauts for transport from station to station on the mission's three moonwalks, the LRV was used to transport the astronauts' tools, communications equipment, and the lunar samples they gathered.<ref name="lunarrover">{{cite web |title=Lunar Roving Vehicle (LRV) |url=https://airandspace.si.edu/explore-and-learn/topics/apollo/apollo-program/spacecraft/lrv.cfm |website=The Apollo Program |publisher=National Air and Space Museum |access-date=February 8, 2022 |archive-date=February 8, 2022 |archive-url=https://web.archive.org/web/20220208032714/https://airandspace.si.edu/explore-and-learn/topics/apollo/apollo-program/spacecraft/lrv.cfm |url-status=dead }}</ref> The Apollo 17 LRV was also used to carry some of the scientific instruments, such as the [[Lunar Traverse Gravimeter|Traverse Gravimeter Experiment (TGE)]] and Surface Electrical Properties (SEP) experiment.<ref name="alsjtge" /><ref name="sep">{{cite web|title=Science Experiments – Surface Electrical Properties|url=http://www.lpi.usra.edu/lunar/missions/apollo/apollo_17/experiments/sep/|work=Apollo 17 Mission|publisher=Lunar and Planetary Institute|access-date=February 7, 2022|archive-date=October 3, 2011|archive-url=https://web.archive.org/web/20111003195214/http://www.lpi.usra.edu/lunar/missions/apollo/apollo_17/experiments/sep/|url-status=live}}</ref> The Apollo 17 LRV traveled a cumulative distance of approximately {{convert|35.7|km|mi nmi|abbr=on}} in a total drive time of about four hours and twenty-six minutes; the greatest distance Cernan and Schmitt traveled from the lunar module was about {{convert|7.6|km|mi nmi|abbr=on}}.{{sfn|Orloff 2004|loc=Statistical Tables: Extravehicular Activity}}

This was the only mission to carry the TGE, which was built by [[Draper Laboratory]] at the [[Massachusetts Institute of Technology]]. As gravimeters had been useful in studying the Earth's internal structure, the objective of this experiment was to do the same on the Moon. The gravimeter was used to obtain relative gravity measurements at the landing site in the immediate vicinity of the lunar module, as well as various locations on the mission's traverse routes. Scientists would then use this data to help determine the geological substructure of the landing site and the surrounding vicinity. Measurements were taken while the TGE was mounted on the LRV, and also while the device was placed on the lunar surface. A total of 26 measurements were taken with the TGE during the mission's three moonwalks, with productive results.<ref name="alsjtge">{{cite web|url=http://www.hq.nasa.gov/alsj/a17/a17-TGE.html|title=Apollo 17 Traverse Gravimeter Experiment|publisher=NASA|editor-first=Eric M.|editor-last=Jones|editor2-first=Ken|editor2-last=Glover|work=Apollo 17 Lunar Surface Journal|access-date=November 29, 2021|archive-date=September 7, 2011|archive-url=https://web.archive.org/web/20110907121516/http://www.hq.nasa.gov/alsj/a17/a17-TGE.html|url-status=live}}</ref>

The SEP was also unique to Apollo 17, and included two major components: a transmitting antenna deployed near the lunar module and a receiver mounted on the LRV. At different stops during the mission's traverses, electrical signals traveled from the transmitting device, through the ground, and were received at the LRV. The electrical properties of the [[lunar regolith]] could be determined by comparison of the transmitted and received electrical signals. The results of this experiment, which are consistent with [[Moon rock|lunar rock]] composition, show that there is almost no water in the area of the Moon in which Apollo 17 landed, to a depth of {{convert|2|km|mi nmi|abbr=on}}.<ref name="sep" />

A {{convert|2.4|meter|feet|abbr=on}} long, {{convert|2|cm|inch|abbr=on}} diameter{{sfn|Apollo 17 Press Kit|p=46}} device, the Lunar Neutron Probe was inserted into one of the holes drilled into the surface to collect core samples. It was designed to measure the quantity of neutrons which penetrated to the detectors it bore along its length. This was intended to measure the rate of the "gardening" process on the lunar surface, whereby the regolith on the surface is slowly mixed or buried due to micrometeorites and other events. Placed during the first EVA, it was retrieved during the third and final EVA. The astronauts brought it with them back to Earth, and the measurements from it were compared with the evidence of neutron flux in the core that had been removed from the hole it had been placed in. Results from the probe and from the cores were instrumental in current theories that the top centimeter of lunar regolith turns over every million years, whereas "gardening" to a depth of one meter takes about a billion years.<ref name ="probe">{{cite web|publisher=[[Lunar and Planetary Institute]]|work=Apollo 17 Mission|title=Science Experiments – Lunar Neutron Probe|date=2019|access-date=February 12, 2022|url=https://www.lpi.usra.edu/lunar/missions/apollo/apollo_17/experiments/lnp/|archive-date=September 8, 2021|archive-url=https://web.archive.org/web/20210908125848/https://www.lpi.usra.edu/lunar/missions/apollo/apollo_17/experiments/lnp/|url-status=live}}</ref>