Editing Apollo 16 (section)

===Particles and Fields Subsatellite PFS-2===
[[Image:Apollo 15 Subsatellite.jpg|thumb|right|Artist's conception of subsatellite deployment]]

The Apollo 16 Particles and Fields Subsatellite (PFS-2) was a small satellite released into lunar orbit from the service module. Its principal objective was to measure charged particles and magnetic fields all around the Moon as the Moon orbited Earth, similar to its sister spacecraft, [[PFS-1]], released eight months earlier by Apollo 15. The two probes were intended to have similar orbits, ranging from {{convert|55|to|76|mi|km|abbr=off|order=flip|sp=us}} above the lunar surface.<ref name=nasa20061106>{{cite web |title=Bizarre Lunar Orbits |url=https://science.nasa.gov/science-news/science-at-nasa/2006/06nov_loworbit/ |last=Bell |first=Trudy E. |date=November 6, 2006 |editor-last=Phillips |editor-first=Tony |work=Science@NASA |publisher=[[NASA]] |access-date=September 7, 2021 |archive-date=December 4, 2021 |archive-url=https://web.archive.org/web/20211204040014/https://science.nasa.gov/science-news/science-at-nasa/2006/06nov_loworbit/ |url-status=dead }}</ref>

Like the Apollo 15 subsatellite, PFS-2 was expected to have a lifetime of at least a year before its [[Orbital decay|orbit decayed]] and it crashed onto the lunar surface. The decision to bring Apollo 16 home early after there were difficulties with the main engine meant that the spacecraft did not go to the orbit which had been planned for PFS-2. Instead, it was ejected into a lower-than-planned orbit and crashed into the Moon a month later on May 29, 1972, after circling the Moon 424 times.{{sfn|Mission Report|pp=5-4—5-5}} This brief lifetime was because lunar [[mascon]]s were near to its orbital ground track and helped pull PFS-2 into the Moon.{{sfn|Orloff & Harland 2006|p=480}}