Apollo Lunar Module

Grumman Apollo LM
Missing image Apollo_16_LM.jpg Apollo LM on lunar surface
Description
Role:	Lunar landing
Crew:	2; CDR, LM pilot
Dimensions
Height:	20.9 ft	6.37 m
Diameter:	14 ft	4.27 m
Landing gear span:	29.75 ft	9.07 m
Volume:	235 ft3	6.65 m3
Masses
Ascent module:	10,024 lb	4,547 kg
Descent module:	22,375 lb	10,149 kg
Total:	32,399 lb	14,696 kg
Rocket engines
LM RCS (N2O4/UDMH) x 16:	100 lbf ea	441 N
Ascent Propulsion System (N2O4/UDMH) x 1:	3,500 lbf ea	15.6 kN
Descent Propulsion System (N2O4/UDMH) x 1:	9,982 lbf ea	44.40 kN
Performance
Endurance:	3 days	72 hours
Apogee:	100 miles	160 km
Perigee:	surface	surface
Spacecraft delta v:	15,390 ft/s	4,690 m/s
Apollo LM diagram
Missing image LEM-linedrawing.png Apollo LM diagram (NASA)
Grumman Apollo LM

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.

Contents

1 History 2 Lunar Module (LM) specifications 3 Lunar Modules produced 4 External links 5 References

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 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 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.

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

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

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.)

External links

• Nasa catalogue: Apollo 14 Lunar Module (http://nssdc.gsfc.nasa.gov/database/MasterCatalog?sc=1971-008C)
• Space/Craft Assembly & Test Remembered (http://users.specdata.com/home/pullo/) – A site "dedicated to the men and women that designed, built and tested the Lunar Module at Grumman Aerospace Corporation, Bethpage, New York"
• Apollo 11 LM Structures handout for LM-5 (http://history.nasa.gov/alsj/a11/a11LM5structures.pdf) (PDF) – Training document given to astronauts which illustrates all discrete LM structures
• Apollo 15 LM Activation Checklist for LM-10 (http://history.nasa.gov/ap15fj/lmactindex.htm) – Checklist detailing how to prepare the LM for activation and flight during a mission

References

• 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 (http://www.hq.nasa.gov/office/pao/History/SP-4205/cover.html) NASA SP-4205.
• Sullivan, Scott P., Virtual LM: A Pictoral Essay of the Engineering and Construction of the Apollo Lunar Module. Apogee Books. ISBN 1894959140de:Mondlandefähre