Editing Apollo Lunar Module (section)

===Design phase===
[[File:Lunar Lander Model.jpg|thumb|This 1963 model depicts the second LEM design, which gave rise to informal references as "the bug".]]
The Apollo Lunar Module was chiefly designed by Grumman aerospace engineer [[Thomas J. Kelly (aerospace engineer)|Thomas J. Kelly]].<ref>{{cite news|url=https://www.nytimes.com/2002/03/27/nyregion/t-j-kelly-72-dies-father-of-lunar-module.html|title=T. J. Kelly, 72, Dies; Father of Lunar Module|first=Warren E.|last=Leary|newspaper=The New York Times|date=March 27, 2002|access-date=February 18, 2017|archive-date=June 23, 2017|archive-url=https://web.archive.org/web/20170623183449/http://www.nytimes.com/2002/03/27/nyregion/t-j-kelly-72-dies-father-of-lunar-module.html|url-status=live}}</ref> The first LEM design looked like a smaller version of the Apollo command and service module (a cone-shaped cabin atop a cylindrical propulsion section) with folding legs. The second design invoked the idea of a helicopter cockpit with large curved windows and seats to improve the astronauts' visibility for hover and landing. This also included a second, forward docking port, allowing the LEM crew to take an active role in docking with the CSM.

As the program continued, there were numerous redesigns to save weight, improve safety, and fix problems. First to go were the heavy cockpit windows and the seats; the astronauts would stand while flying the LEM, supported by a cable and pulley system, with smaller triangular windows giving them sufficient visibility of the landing site. Later, the redundant forward docking port was removed, which meant the Command Pilot gave up active control of the docking to the Command Module Pilot; he could still see the approaching CSM through a small overhead window. Egress while wearing bulky extra-vehicular activity spacesuits was eased by a simpler forward hatch ({{cvt|32|x|32|in|disp=or}}).

The configuration was frozen in April 1963, when the ascent and descent engine designs were decided. In addition to Rocketdyne, a parallel program for the descent engine<ref name="NASA"/> was ordered from [[TRW Inc.#Space exploration|Space Technology Laboratories (TRW)]] in July 1963, and by January 1965 the Rocketdyne contract was cancelled.

Power was initially to be produced by [[fuel cell]]s built by [[Pratt and Whitney]] similar to the CSM, but in March 1965 these were discarded in favor of an all-battery design.<ref>{{cite web|url=http://www.astronautix.com/craft/lmerical.htm|title=LM Electrical|publisher=[[Encyclopedia Astronautica]]|url-status=dead|archive-url=https://web.archive.org/web/20100201084039/http://astronautix.com/craft/lmerical.htm|archive-date=February 1, 2010}}</ref>

The initial design had three landing legs, the lightest possible configuration. But as any particular leg would have to carry the weight of the vehicle if it landed at a significant angle, this was also the least stable configuration if one of the legs were damaged during landing. The next landing gear design iteration had five legs and was the most stable configuration for landing on an unknown terrain. That configuration, however, was too heavy and the designers compromised on four landing legs.<ref>{{cite web|url=http://www.astronautix.com/craft/lmlggear.htm|title=LM Landing Gear|publisher=Encyclopedia Astronautica|url-status=dead|archive-url=https://web.archive.org/web/20100201083530/http://astronautix.com/craft/lmlggear.htm|archive-date=February 1, 2010}}</ref>

In June 1966, the name was changed to Lunar Module (LM), eliminating the word ''excursion''.<ref>{{cite web |title=SP-4402 Origins of NASA Names |url=https://history.nasa.gov/SP-4402/ch4.htm |website=NASA History |publisher=NASA |access-date=January 16, 2015 |archive-date=December 4, 2016 |archive-url=https://web.archive.org/web/20161204214326/http://history.nasa.gov/SP-4402/ch4.htm |url-status=live }}</ref><ref>Scheer, Julian W. (Assistant Administrator for Public Affairs, NASA). Memorandum from Project Designation Committee, June 9, 1966.</ref> According to [[George Low]], Manager of the Apollo Spacecraft Program Office, this was because NASA was afraid that the word ''excursion'' might lend a frivolous note to Apollo.<ref>{{cite book |last=Cortright |first=Edgar M. |title=Apollo expeditions to the moon |url=https://archive.org/details/apolloexpedition00cort |url-access=registration |year=1975 |publisher=Scientific and Technical Information Office, National Aeronautics and Space Administration }} [https://history.nasa.gov/SP-350/ch-4-2.html NASA.gov ch-4-2] {{Webarchive|url=https://web.archive.org/web/20210428015444/https://history.nasa.gov/SP-350/ch-4-2.html |date=April 28, 2021 }}.</ref> Despite the name change, the astronauts and other NASA and Grumman personnel continued to pronounce the abbreviation as ({{IPAc-en|l|ɛ|m}}) instead of the letters "L-M".