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The Apollo Lunar Module was the Lander portion of the Apollo Spacecraft built for the US Apollo Program to achieve the transit from Moon orbit to the surface and back. The module was also known as the '''LM''' from the manufacturer designation (yet pronounced "LEM" from NASA's early name for it, '''Lunar Excursion Module'''). The module was designed to carry two crew in a 6.65 m³ space. The total module was 6.4 m high and 4.3 m across, resting on four legs. It consisted of two stages—the descent stage module and the ascent stage. The total mass of the module was 15,264 kg with the majority of that (10,334 kg) in the descent stage. HISTORY The Apollo Lunar Module came into being because NASA chose to reach the moon via a lunar orbit rendezvous (LOR) instead of a direct ascent or Earth orbit rendezvous (EOR) (see Choosing A Mission Mode for more information on the available rendezvous types). Both a direct ascent and an EOR would have involved the entire Apollo spacecraft landing 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. The LM contract was given to Grumman Aircraft Engineering and a number of subcontractors. Grumman had begun lunar orbit rendezvous studies in late 1950s and again in 1962. In July 1962 eleven firms were invited to submit proposals for the LM. Nine did so in September, and Grumman was awarded the contract that same month. 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) on the LM 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 . To learn lunar landing techniques, astronauts practiced in the Lunar Landing Research Vehicle ( LLRV ), a flying vehicle that simulated the Lunar Module on earth. A 200'-tall, 400'-long gantry structure was constructed at NASA Langley Research Center ; the LLRV was suspended in this structure from a crane, and "piloted" by moving the crane. (The facility is now known as the Impact Dynamics Research Facility, and is used for aircraft crash tests.) Configuration freeze did not start until April 1963 when the ascent and descent engine design was decided. In addition to Rocketdyne a parallel program for the descent engine was ordered from Space Technology Laboratories in July 1963, and by January 1965 the Rocketdyne contract was cancelled. As the program continued there were numerous redesigns to save weight (including 'Operation Scrape'), improve safety, and fix problems. For example initially the module was to be powered by Fuel Cell s, built by Pratt And Whitney but in March 1965 they were paid off in favor of an all battery design. The initial design iteration had the LEM with three landing legs. It was felt that three legs, though the lightest configuration, was the least stable 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 was too heavy and the compromise was four landing legs. The first LM flight was on January 22, 1968 when the unmanned LM-1 was launched on a Saturn IB for testing of propulsion systems in orbit. The next LM flight was aboard Apollo 9 using LM-3 on March 3, 1969 as a manned flight (McDivitt, Scott and Schweickart) to test a number of systems in Earth orbit including LM and CSM crew transit, LM propulsion, separation and docking. Apollo 10 , which launched on May 18, 1969, was another series of tests, this time in lunar orbit with the LM separating and descending to within 10 km of the surface. From the successful tests the LM successfully descended and ascended from the lunar surface with Apollo 11 . In April 1970, the lunar module Aquarius played an unexpected role in saving the lives of the three astronauts of the Apollo 13 mission (Commander James A. Lovell Jr., CSM pilot John L. Swigert Jr., and LM pilot Fred W. Haise Jr.), after an electrical short circuit caused an oxygen tank in that mission's Service Module to overheat and explode. Aquarius served as a refuge for the astronauts during their return to Earth orbit, while its batteries were used to recharge the vital re-entry batteries of the command module that brought the astronauts through the Earth's atmosphere and to a safe spashdown on April 17 , 1970 . The LM's descent engine, designed to slow the vehicle during its descent to the moon, was used to accelerate the Apollo 13 spacecraft around the moon and back to Earth. After the accident, the LM's systems, designed to support two astronauts for 45 hours, actually supported three astronauts for 90 hours. LUNAR MODULE (LM) SPECIFICATIONS The Lunar Module was the portion of the Apollo spacecraft that landed on the moon and returned to lunar orbit. It is divided into two major parts, the Descent Module and the Ascent Module. The Descent Modules contains the landing gear, landing radar antenna, descent rocket engine, and fuel to land on the moon. It also had several cargo compartments used to carry among other things, the Apollo Lunar Surface Experiment Packages ALSEP , Mobile Equipment Cart (a hand pulled equipment cart— Apollo 14 ), the Lunar Rover (moon car)— Apollo 15 , 16 and 17), surface television camera, surface tools and lunar sample collection boxes. Also, on the ladder of the descent stage is attached a Plaque . The Ascent Module contains the crew cabin, instrument panels, overhead hatch/docking port, forward hatch, reaction control system, radar and communications antennas, ascent rocket engine and fuel to return to lunar orbit and rendezvous with the Apollo Command and Service Modules.
Thus the thrust was less than the weight on Earth, but enough on the Moon.
.]] LUNAR MODULES PRODUCED LM TRUCK The Apollo LM Truck was a stand-alone LM descent stage intended to deliver up to five metric tons of payload to the Moon for an unmanned landing. This technique was intended to deliver equipment and supplies to a permanent manned Lunar Base that was never built. As originally proposed, it would be launched on a Saturn V with a full Apollo crew to accompany it to lunar orbit and then guide it to a landing next to the base; the base crew would then unload the "truck" while the orbiting crew returned to earth. IN FICTION The LM and LM Truck, using a modified mission profile, appear in Shane Johnson 's novel '' Ice '', about a fictional ''Apollo 19'' mission that takes a disastrous turn. In this scenario, the LM Truck is delivered on a Saturn IB and makes a preprogrammed landing at the proposed landing site; a J-mission Apollo crew then lands a conventional LM next to it, in a feat of precision landing recalling that of Pete Conrad during '' Apollo 12 ''. Also in this novel, the LM, which happens to be LM-13, fails to fire its ascent engine, stranding two astronauts on the Moon--something that never happened in Project Apollo. In the movie Superman 2 , the film's supervillain's visit the moon on their way to earth, and encounter a modernized version of the LM (still bearing an obvious resemblance), which they destroy along with its crew. SUCCESSORS The LM design was later incorporated into the Apollo Telescope Mount on the successful Skylab space station. Originally planned to be launched on an unmanned Saturn 1B rocket, similar to the unmanned Apollo 5 test flight, NASA decided to save costs and launch the ATM with the station itself. This decision saved the station, as the ATM's "windmill" solar panels helped keep the station operation after its surviving solar panel on the station was damaged during launch (the other was ripped off). In 2005, NASA announced that the successor to the Space Shuttle , the Crew Exploration Vehicle , would feature, for its lunar landing missions, a Lunar Surface Access Module (LSAM) which is roughly based on the Apollo LM. Like the LM, it has a descent and ascent module (the latter to house the crew), but unlike the LM, it would be powered by liquid hydrogen (LH2) and liquid oxygen (LO2) for the landing phase, and by liquid methane (LCH4) and LOX for the ascension phase. The major differences between the LSAM and the LM is that the LSAM would be launched separately into a Low Earth Orbit atop of the Cargo Launch Vehicle (CaLV), a Shuttle Derived Launch Vehicle , with the manned CEV being launched separately atop of the Crew Launch Vehicle (CLV). Both vehicles would dock into Low Earth Orbit similar to the Earth Orbit Rendezvous plan in Apollo's early stages. The LSAM, unlike the LM, will also be used to break the CEV/LSAM "stack" into lunar orbit, hence the use of LOX/LH2 in the descent stage. EXTERNAL LINKS
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