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Apollo 13 Lunar Module/ALSEP



The Apollo 13 Lunar Module (LM or LEM) was originally supposed to land at the Fra Mauro region of the Moon. The Apollo 13 mission was aborted as a lunar landing mission on 13 April 1970, 2 days after launch, when an oxygen tank on the Command and Service Module (CSM) overheated and exploded. The LM, designed to support two astronauts for 45 hours, was used as a lifeboat to house the three astronauts (Commander James A. Lovell Jr., CSM pilot John L. Swigert Jr., and LM pilot Fred W. Haise Jr.) for 90 hours, as the CSM could not provide life support. Energy and water consumption were cut drastically for the duration of the trip, and the CM lithium hydroxide cannisters, used to scrub carbon dioxide out of the air, were adapted for use on the LM. The Apollo 13 continued on to the Moon, and the LM descent engine was used to accelerate the spacecraft around the Moon and back to Earth. The LM was jettisoned shortly before reaching Earth, the astronauts returning to the Command Module for the reentry. The LM re-entered and burned in the Earth's atmosphere over the southwest Pacific, any surviving pieces impacted in the deep ocean off the coast of New Zealand.

Lunar Module Spacecraft and Subsystems

The lunar module was a two-stage vehicle designed for space operations near and on the Moon. The spacecraft mass of 15,188 kg was the mass of the LM including astronauts, expendables and 10,691 kg of propellants. The ascent and descent stages of the LM operated as a unit until staging, when the ascent stage functioned as a single spacecraft for rendezvous and docking with the command and service module (CSM). The descent stage comprised the lower part of the spacecraft and was an octagonal prism 4.2 meters across and 1.7 m thick. Four landing legs with round footpads were mounted on the sides of the descent stage and held the bottom of the stage 1.5 m above the surface. The distance between the ends of the footpads on opposite landing legs was 9.4 m. One of the legs had a small astronaut egress platform and ladder. A one meter long conical descent engine skirt protruded from the bottom of the stage. The descent stage contained the landing rocket, two tanks of aerozine 50 fuel, two tanks of nitrogen tetroxide oxidizer, water, oxygen and helium tanks and storage space for the lunar equipment and experiments, and in the case of Apollo 15, 16, and 17, the lunar rover. The descent stage was designed as a platform for launching the ascent stage from the Moon.

The ascent stage was an irregularly shaped unit approximately 2.8 m high and 4.0 by 4.3 meters in width mounted on top of the descent stage. The ascent stage housed the astronauts in a pressurized crew compartment with a volume of 6.65 cubic meters. There was an ingress-egress hatch in one side and a docking hatch for connecting to the CSM on top. Also mounted along the top were a parabolic rendezvous radar antenna, a steerable parabolic S-band antenna, and 2 in-flight VHF antennas. Two triangular windows were above and to either side of the egress hatch and four thrust chamber assemblies were mounted around the sides. At the base of the assembly was the ascent engine. The stage also contained an aerozine 50 fuel and an oxidizer tank, and helium, liquid oxygen, gaseous oxygen, and reaction control fuel tanks. There were no seats in the LM. A control console was mounted in the front of the crew compartment above the ingress-egress hatch and between the windows and two more control panels mounted on the side walls. The ascent stage was to be launched from the Moon at the end of lunar surface operations and return the astronauts to the CSM.

The descent engine was a deep-throttling ablative rocket with a maximum thrust of about 45,000 N mounted on a gimbal ring in the center of the descent stage. The ascent engine was a fixed, constant-thrust rocket with a thrust of about 15,000 N. Maneuvering was achieved via the reaction control system, which consisted of the four thrust modules, each one composed of four 450 N thrust chambers and nozzles pointing in different directions. Telemetry, TV, voice, and range communications with Earth were all via the S-band antenna. VHF was used for communications between the astronauts and the LM, and the LM and orbiting CSM. There were redundant tranceivers and equipment for both S-band and VHF. An environmental control system recycled oxygen and maintained temperature in the electronics and cabin. Power was provided by 6 silver-zinc batteries. Guidance and navigation control were provided by a radar ranging system, an inertial measurement unit consisting of gyroscopes and accelerometers, and the Apollo guidance computer.

Alternate Names

  • Aquarius
  • LM-7
  • ALSEP 13
  • LEM 13
  • Apollo13ALSEP
  • 1970-029C

Facts in Brief

Launch Date: 1970-04-11
Launch Vehicle: Saturn 5
Launch Site: Cape Canaveral, United States
Mass: 15196 kg

Funding Agency

  • NASA-Office of Manned Space Flight United States


  • Planetary Science
  • Space Physics

Additional Information

Questions and comments about this spacecraft can be directed to: Dr. David R. Williams



NameRoleOriginal AffiliationE-mail

Selected References

  • McDivitt, J. A., Apollo 13 mission report, NASA-MSC, MSC-02680, Houston, TX, Sept. 1970.
Diagram of Apollo 11 Lunar Module

Diagram of the Apollo Lunar Module. (Courtesy of NASA History Office.)

Other Sources of Apollo 13 Information at NSSDCA

Apollo 13 Command Module
Details on the Apollo 13 accident
Apollo 13 Page

Other Sources of Apollo Information at NSSDCA

Apollo Page
Lunar Science Page

Related Information at NSSDCA

Moon Page

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