History
The Lunar Module (originally designated the Lunar Excursion Module, known by the acronym LEM) was designed after NASA chose to reach the Moon via Lunar Orbit Rendezvous (LOR) instead of the direct ascent or Earth Orbit Rendezvous (EOR) methods. Both direct ascent and EOR would have involved landing a much heavier, complete Apollo spacecraft on the Moon. Once the decision had been made to proceed using LOR, it became necessary to produce a separate craft capable of reaching the lunar surface and ascending back to lunar orbit. The Lunar Module was built by Grumman Aircraft Engineering and was chiefly designed by the American aerospace engineer, Tom Kelly. Grumman had begun lunar orbit rendezvous studies in late 1950s and again in 1961. In July 1962, eleven firms were invited to submit proposals for the LEM. Nine companies responded in September, answering 20 specific questions posed by the NASA RFP in a 60-page limited technical proposal. Grumman was awarded the contract two months later. The contract cost was expected to be around $350 million. There were initially four major subcontractors—Bell Aerosystems (ascent engine), Hamilton Standard (environmental control systems), Marquardt (reaction control system) and Rocketdyne (descent engine).
The Primary Guidance, Navigation and Control System (PGNCS) was developed by the MIT Instrumentation Laboratory; the Apollo Guidance Computer was manufactured by Raytheon (a similar guidance system was used in the Command Module). A backup navigation tool, the Abort Guidance System (AGS), was developed by TRW.
Over the course of its development, the name was officially changed to Lunar Module (LM), eliminating the word "excursion". 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. After the name change from "LEM" to "LM", the pronunciation of the abbreviation did not change, as the habit became ingrained among engineers, the astronauts, and the media to universally pronounce "LM" as "lem" which is easier than saying the letters individually.
Read more about this topic: Apollo Lunar Module
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