Editing Apollo 13 (section)

== Experiments and scientific objectives ==
[[File:Lovell and Haise geology training (S70-20253).jpg|thumb|right|upright|Lovell (left) and Haise during geology training in Hawaii, January 1970]]

Apollo&nbsp;13's designated landing site was near [[Fra Mauro (crater)|Fra Mauro crater]]; the [[Fra Mauro formation]] was believed to contain much material spattered by the impact that had filled the [[Imbrium basin]] early in the Moon's history. Dating it would provide information not only about the Moon, but about the Earth's early history. Such material was likely to be available at Cone crater, a site where an impact was believed to have drilled deep into the lunar [[regolith]].{{sfn|Harland|1999|pp=51–53}}

Apollo 11 had left a [[seismometer]] on the Moon, but the solar-powered unit did not survive its first two-week-long lunar night. The Apollo 12 astronauts [[Apollo 12 Passive Seismic Experiment|also left one]] as part of its ALSEP, which was nuclear-powered.{{sfn|Harland|1999|pp=38–39}} Apollo&nbsp;13 also carried a seismometer (known as the Passive Seismic Experiment, or PSE), similar to Apollo 12's, as part of its ALSEP,  to be left on the Moon by the astronauts.{{sfn|Apollo 13 Press Kit|1970|p=29}} That seismometer was to be calibrated by the impact, after jettison, of the ascent stage of Apollo&nbsp;13's LM, an object of known mass and velocity impacting at a known location.{{sfn|Apollo 13 Press Kit|1970|p=42}}

Other ALSEP experiments on Apollo&nbsp;13 included a [[Heat Flow Experiment]] (HFE), which would involve drilling two holes {{convert|10|ft|order=flip}} deep.{{sfn|Apollo 13 Press Kit|1970|p=33}} This was Haise's responsibility; he was also to drill a third hole of that depth for a core sample.{{sfn|''Science News'' 1970-04-04|p=354}} A Charged Particle Lunar Environment Experiment (CPLEE) measured the protons and electrons of solar origin reaching the Moon.{{sfn|Apollo 13 Press Kit|1970|p=49}} The package also included a Lunar Atmosphere Detector (LAD){{sfn|Apollo 13 Press Kit|1970|p=51}} and a Dust Detector, to measure the accumulation of debris.{{sfn|Apollo 13 Press Kit|1970|p=62}} The Heat Flow Experiment and the CPLEE were flown for the first time on Apollo&nbsp;13; the other experiments had been flown before.{{sfn|''Science News'' 1970-04-04|p=354}}

[[File:Haise RTG (Ap13-70-H-103).jpg|thumb|left|Haise practices removing the fuel capsule from its transport cask mounted on the LM. The real cask sank unopened into the Pacific Ocean with its radioactive contents.]]
To power the ALSEP, the [[Systems for Nuclear Auxiliary Power#SNAP-27|SNAP-27]] radioisotope thermoelectric generator (RTG) was flown. Developed by the [[United States Atomic Energy Commission|U.S. Atomic Energy Commission]], SNAP-27 was first flown on Apollo 12. The fuel capsule contained about {{convert|8.36|lb|order=flip}} of [[Plutonium(IV) oxide|plutonium oxide]]. The cask placed around the capsule for transport to the Moon was built with heat shields of graphite and of beryllium, and with structural parts of titanium and of [[Inconel]] materials. Thus, it was built to withstand the heat of reentry into the Earth's atmosphere rather than pollute the air with plutonium in the event of an aborted mission.{{sfn|Apollo 13 Press Kit|1970|p=65}}

A United States flag was also taken, to be erected on the Moon's surface.{{sfn|Apollo 13 Press Kit|1970|pp=33, 65}} For Apollo 11 and 12, the flag had been placed in a heat-resistant tube on the front landing leg; it was moved for Apollo&nbsp;13 to the Modularized Equipment Stowage Assembly (MESA) in the LM descent stage. [[Lunar Flag Assembly|The structure to fly the flag]] on the airless Moon was improved from Apollo 12's.{{sfn|Apollo 13 Press Kit|1970|p=73}}

For the first time, red stripes were placed on the helmet, arms and legs of the commander's [[Apollo/Skylab A7L|A7L]] spacesuit. This was done as, after Apollo 11, those reviewing the images taken had trouble distinguishing Armstrong from Aldrin, but the change was approved too late for Apollo 12.<ref name = "red stripe">{{cite web|title=Commander's stripes|website=Apollo Lunar Surface Journal|publisher=[[NASA]]|access-date=July 20, 2019|url=https://www.hq.nasa.gov/alsj/alsj-CDRStripes.html|last=Jones|first=Eric M.|date=February 20, 2006}}</ref> New drink bags that attached inside the helmets and were to be sipped from as the astronauts walked on the Moon were demonstrated by Haise during Apollo&nbsp;13's final television broadcast before the accident.{{sfn|Turnill|2003|p=316}}<ref>{{cite web|url=https://www.hq.nasa.gov/alsj/alsj-DrinkFood.html|title=Water Gun, Helmet Feedport, In-Suit Drink Bag, and Food Stick|last1=Jones|first1=Eric M.|date=March 3, 2010|website=Apollo Lunar Surface Journal|publisher=NASA|access-date=November 15, 2019}}</ref>

Apollo&nbsp;13's primary mission objectives were to: "Perform selenological inspection, survey, and sampling of materials in a preselected region of the Fra Mauro Formation. Deploy and activate an Apollo Lunar Surface Experiments Package. Develop man's capability to work in the lunar environment. Obtain photographs of candidate exploration sites."{{sfn|Accident report|p=3-26}} The astronauts were also to accomplish other photographic objectives, including of the [[Gegenschein]] from lunar orbit, and of the Moon itself on the journey back to Earth. Some of this photography was to be performed by Swigert as Lovell and Haise walked on the Moon.{{sfn|Orloff & Harland|2006|p=385}} Swigert was also to take photographs of the [[Lagrangian point]]s of the Earth-Moon system. Apollo&nbsp;13 had twelve cameras on board, including those for television and moving pictures.{{sfn|''Science News'' 1970-04-04|p=354}} The crew was also to downlink [[bistatic radar]] observations of the Moon. None of these was attempted because of the accident.{{sfn|Orloff & Harland|2006|p=385}}