Editing Apollo 17 (section)

=== Solo activities ===
While Cernan and Schmitt were on the lunar surface, Evans remained alone in the CSM in lunar orbit and was assigned a number of observational and scientific tasks to perform while awaiting the return of his crewmates. In addition to the operation of the various orbital science equipment contained in the CSM's SIM bay, Evans conducted both visual and photographic observation of surface features from his aerial vantage point.<ref name="evans">{{cite web |title=Ronald E. Evans |url=https://www.nmspacemuseum.org/inductee/ronald-e-evans/ |publisher=New Mexico Museum of Space History |access-date=February 8, 2022 |archive-date=January 26, 2022 |archive-url=https://web.archive.org/web/20220126011723/https://www.nmspacemuseum.org/inductee/ronald-e-evans/ |url-status=live }}</ref> The orbit of the CSM having been modified to an elliptical orbit in preparation for the LM's departure and eventual descent, one of Evans' solo tasks in the CSM was to circularize its orbit such that the CSM would remain at approximately the same distance above the surface throughout its orbit.<ref>{{cite web |last1=Fowler |first1=Wallace T. |title=Apollo Timeline (Apollo 17) |url=http://www.tsgc.utexas.edu/spacecraft/apollo17/timeline.html |website=Lunar Mission Characteristics |publisher=University of Texas |access-date=February 8, 2022 |archive-date=February 8, 2022 |archive-url=https://web.archive.org/web/20220208230120/http://www.tsgc.utexas.edu/spacecraft/apollo17/timeline.html |url-status=dead }}</ref> Evans observed geological features visible to him and used handheld cameras to record certain visual targets.<ref name="evans"/> Evans also observed and sketched the [[solar corona]] at "sunrise," or the period of time during which the CSM would pass from the darkened portion of the Moon to the illuminated portion when the Moon itself mostly obscured the sun.<ref>{{cite journal |last1=Zook |first1=H. A. |last2=Potter |first2=A. E. |last3=Cooper |first3=B. L. |title=The Lunar Dust Exosphere and Clementine Lunar Horizon Glow |journal=Abstracts of the Lunar and Planetary Science Conference |date=1995 |volume=26 |page=1577 |bibcode=1995LPI....26.1577Z |url=https://adsabs.harvard.edu/full/1995LPI....26.1577Z |access-date=February 8, 2022 |archive-date=February 8, 2022 |archive-url=https://web.archive.org/web/20220208231558/https://adsabs.harvard.edu/full/1995LPI....26.1577Z |url-status=live }}</ref> To photograph portions of the surface that were not illuminated by the sun while Evans passed over them, Evans relied in conjunction on [[Exposure (photography)|exposure]] and [[Earthlight (astronomy)|Earthlight]]. Evans photographed such features as the craters [[Eratosthenes (crater)|Eratosthenes]] and Copernicus, as well as the vicinity of [[Mare Orientale]], using this technique.{{sfn|Apollo 17 Mission Report|pp=10-34–10-38}} According to the Apollo 17 Mission Report, Evans was able to capture all scientific photographic targets, as well as some other targets of interest.{{sfn|Apollo 17 Mission Report|p=10-37}}

[[File:AS17-158-23902.jpg|thumb|left|An oblique, black-and-white view of a portion of Mare Orientale from the CSM, illustrating the illuminating effect of Earthlight on the lunar terrain below during local nighttime; Evans reported seeing a light "flash" apparently originating from the surface in this area]]
Similarly to the crew of Apollo 16, Evans (as well as Schmitt, while in lunar orbit) reported seeing light "flashes" apparently originating from the lunar surface, known as [[Transient lunar phenomenon|transient lunar phenomena]] (TLP); Evans reported seeing these "flashes" in the vicinity of [[Grimaldi (crater)|Grimaldi crater]] and Mare Orientale. The causes of TLP are not well-understood and, though inconclusive as an explanation, both of the sites in which Evans reported seeing TLP are the general locations of [[Outgassing#From rock|outgassing]] from the Moon's interior. [[Meteorite]] impacts are another possible explanation.{{sfn|Crotts 2014|pp=268–269}}<ref>{{cite web |title=Transient Lunar Phenomena Studies |url=http://user.astro.columbia.edu/~arlin/TLP/ |publisher=Columbia University |access-date=December 12, 2021 |archive-date=January 27, 2022 |archive-url=https://web.archive.org/web/20220127044000/http://user.astro.columbia.edu/~arlin/TLP/ |url-status=live }}</ref>

The flight plan kept Evans busy, making him so tired he overslept one morning by an hour, despite the efforts of Mission Control to awaken him. Before the LM departed for the lunar surface, Evans had discovered that he had misplaced his pair of scissors, necessary to open food packets. Cernan and Schmitt lent him one of theirs.{{sfn|Chaikin 1995|p=532}} The instruments in the SIM bay functioned without significant hindrance during the orbital portion of the mission, though the lunar sounder and the mapping camera encountered minor problems.{{sfn|Apollo 17 Mission Report|p=10-38}} Evans spent approximately 148 total hours in lunar orbit, including solo time and time spent together with Cernan and Schmitt, which is more time than any other individual has spent orbiting the Moon.{{sfn|Orloff 2004|loc=Statistical Tables: General Background}}<ref>{{cite news |last1=Howell |first1=Elizabeth |title=Ron Evans: Apollo 17 Command Module Pilot |url=https://www.space.com/20788-ron-evans-astronaut-biography.html |access-date=February 12, 2022 |publisher=Space.com |date=April 23, 2013 |archive-date=December 1, 2017 |archive-url=https://web.archive.org/web/20171201033841/https://www.space.com/20788-ron-evans-astronaut-biography.html |url-status=live }}</ref>

Evans was also responsible for piloting the CSM during the orbital phase of the mission, maneuvering the spacecraft to alter and maintain its orbital trajectory. In addition to the initial orbital recircularization maneuver shortly after the LM's departure, one of the solo activities Evans performed in the CSM in preparation for the return of his crewmates from the lunar surface was the [[Orbital plane (astronomy)|plane change]] maneuver. This maneuver was meant to align the CSM's trajectory to the eventual trajectory of the LM to facilitate rendezvous in orbit. Evans fired the SPS engine of the CSM for about 20 seconds in successfully adjusting the CSM's orbital plane.{{sfn|Orloff 2004|loc=Apollo 17: The Eleventh Mission}}{{sfn|Apollo 17 Mission Report|p=10-38}}