Science Fair Project Encyclopedia
Apollo Lunar Module
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 - a descent stage and a module and ascent stage. The total mass of the module was 15,264 kg with the majority of that (10,334 kg) in the descent stage.
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 1960 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.
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 cells, built by Pratt and Whitney but in March 1965 they were paid off in favor of an all battery design.
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.
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 Module 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.
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.
- Specifications: (Baseline LM)
- Ascent Stage:
- Crew: 2
- Crew cabin volume: 6.65 m³ (235 ft³)
- Height: 3.76 m (12.34 ft)
- Diameter: 4.2 m (13.78 ft)
- Mass including fuel: 4,670 kg (10,300 lb)
- Atmosphere: 100% oxygen at 250 mmHg (33 kPa)
- Water: 2 19.27 kg storage tanks
- Coolant: 11.3 kg of ethylene glycol/water solution
- RCS (Reaction Control System) Propellant mass: 287 kg (633 lb)
- APS Propellant mass: 2,353 kg (5,227 lb)
- RCS thrusters: 16 x 445 N; four quads
- RCS propellants: N2O4/UDMH
- RCS specific impulse: 2.84 kN·s/kg
- APS thrust: 15.6 kN (3,500 lbf)
- APS propellants: N2O4/UDMH
- APS pressurant: 2 x 2.9 kg helium tanks at 21 MPa
- Engine specific impulse: 3.05 kN·s/kg
- Thrust-to-weight ratio: 0.34 lbf/lb (3.3 N/kg)
- Ascent stage delta V: 2,220 m/s (7,280 ft/s)
- Batteries: 4 x 400 A·h silver-zinc batteries
- Power: 26-32 V dc buses
- Ascent Stage:
Thus the thrust was less than the weight on Earth, but enough on the Moon.
- Descent Stage:
- Height: 3.2 m (10.5 ft)
- Diameter: 4.2 m (13.8 ft)
- Landing gear diameter: 9.4 m (30.8 ft)
- Mass including fuel: 10,334 kg (22,783 lb)
- Water: 1 x 151 kg storage tank
- Power: 2 x 296 Ah silver-zinc batteries (secondary system)
- Propellants mass: 8,165 kg (18,000 lb)
- DPS thrust: 45.04 kN (10,125 lbf), throttleable to 4.56 kN (1025 lbf)
- DPS propellants: N2O4/UDMH
- DPS pressurant: 1 x 22 kg supercritical helium tank at 10.72 kPa.
- Engine specific impulse: 3050 N·s/kg
- Descent stage delta V: 2,470 m/s (8,100 ft/s)
- Batteries: 2 x 296 A·h silver-zinc batteries
- Descent Stage:
Lunar Modules produced
|Serial number||Use||Launch date||Current location|
|LM-1||Apollo 5||January 22, 1968||Reentered Earth's atmosphere|
|LM-2|| Not flown||On display at the National Air and Space Museum, Washington, DC|
|LM-3 Spider||Apollo 9||March 3, 1969||Reentered Earth's atmosphere|
|LM-4 Snoopy||Apollo 10||May 18, 1969||Descent stage impacted Moon; Ascent stage in solar orbit|
|LM-5 Eagle||Apollo 11||July 16, 1969||Lunar surface*|
|LM-6 Intrepid||Apollo 12||November 14, 1969||Lunar surface*|
|LM-7 Aquarius||Apollo 13||April 11, 1970||Reentered Earth's atmosphere over Fiji|
|LM-8 Antares||Apollo 14||January 31, 1971||Lunar surface*|
| LM-9|| Not flown|| On display at the Kennedy Space Center (Apollo/Saturn V Center)|
|LM-10 Falcon||Apollo 15||July 26, 1971||Lunar surface*|
|LM-11 Orion||Apollo 16||April 16, 1972||Lunar surface*|
|LM-12 Challenger||Apollo 17||December 7, 1972||Lunar surface*|
| LM-13|| Not flown (meant for later Apollo flights)||Partially completed by Grumman; restored and on display at Cradle of Aviation , Long Island, New York|
| LM-14|| Not flown (meant for later Apollo flights)||Never completed; unconfirmed reports claim that some parts (in addition to parts from LTA-3) are included in LM on display at the Franklin Institute, Philadelphia|
| LM-15|| Not flown (meant for later Apollo flights)|| Scrapped|
(* See List of artificial objects on the Moon for location.)
- Nasa catalogue: Apollo 14 Lunar Module
- Space/Craft Assembly & Test Remembered – A site "dedicated to the men and women that designed, built and tested the Lunar Module at Grumman Aerospace Corporation, Bethpage, New York"
- Kelly, Thomas J. (2001). Moon Lander: How We Developed the Apollo Lunar Module (Smithsonian History of Aviation and Spaceflight Series). Smithsonian Institution Press. ISBN 156098998X.
- Baker, David (1981). The History of Manned Space Flight. Crown Publishers. ISBN 051754377X
- Brooks, Courtney J., Grimwood, James M. and Swenson, Loyd S. Jr (1979) Chariots for Apollo: A History of Manned Lunar Spacecraft NASA SP-4205.
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