Apollo Lunar Module

Apollo 9 Flight Test of the Lunar Module

For ten days, the astronauts put all three Apollo vehicles through their paces in Earth orbit, undocking and then redocking the lunar lander with the command module, just as they would in lunar orbit. Apollo 9 gave proof that the Apollo machines were up to the task of orbital rendezvous and docking.

Initially, the Lunar Module layout was like a smaller version of the Apollo Command/Service Module (a cone-shaped cabin on top of a cyllindrical propulsion section) but with foldable legs. The next idea was more like a helicopter cockpit with large curved windows and seats, to improve the astronauts' visibility for hover and landing. There was also a second, forward docking port, allowing the crew to take an active role in docking with the CSM.

As the program continued, there were numerous redesigns to save weight (including "Operation Scrape"), improve safety, and fix problems. First to go were the heavy cockpit windows, and the seats; the astronauts would stand while flying the LM, supported by a cable and pully system, with smaller triangular windows giving them sufficient visibility of the landing site.

Later, the redundant forward docking port was removed, which meant the Commander gave up active control of the docking to the Command Module Pilot; he could still see the approaching CSM through a small overhead window. These changes resulted in significant weight savings. The new single hatch was simpler than the old version, and was also easier to get through whilst wearing the bulky EVA suit.

A configuration freeze did not start until April 1963, when the ascent and descent engine designs were 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 canceled.

Power was initially to be produced by fuel cells built by Pratt and Whitney similar to the CSM, but in March 1965 these were discarded in favor of an all-battery design.

The initial design had three landing legs. As any particular leg would have to carry the weight of the vehicle if it lands at any significant angle, three legs was the lightest configuration. However, it would be 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, however, was too heavy and the designers compromised on four landing legs.

This model depicts an early Apollo lunar lander concept, called a "bug."

Engineers designed several possible vehicle shapes for both manned and unmanned landers. In 1961, Bruce Lundin, former director of NASA's Lewis Research Centre (now Glenn), chaired a NASA study group that assessed a variety of ways to accomplish a lunar landing mission.

NASA changed the name to Lunar Module or LM from Lunar Excursion Module (LEM), but it was always pronounced "lem".

For this and subsequent missions the crews were allowed to name their own spacecraft. The gangly lunar module was named Spider, and the command module was labeled Gumdrop because of the blue wrapping in which the craft arrived at Kennedy Space Center.

The LEM was built by Grumman Aircraft Engineering, with Tom Kelly leading the engineering project in 1960. Grumman had begun lunar orbit rendezvous studies in the late 1950s. 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) was developed by the MIT Instrumentation Laboratory; the Apollo Guidance Computer was manufactured by Raytheon. A backup navigation tool, the Abort Guidance System (AGS), was developed by TRW.

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Spider, now just the ascent stage, is manouevring near Gumdrop, the Command Module of Apollo 9.

The descent stage of LM-3 Spider (1969-018D) decayed March 22, 1969. The ascent stage (1969-018C) lasted in orbit until October 23rd, 1981!

The Apollo 9 Command Module Gumdrop (1969-018A) is on display at the San Diego Air & Space Museum, San Diego, California. Its service module was jettisoned shortly after the deorbit burn and decayed during re-entry of the command module.

Rusty Schweickart is seen at the hatch - he performed a 37-minute EVA during this mission.

Ascent stage:

The Ascent stage contained the crew cabin; environmental control (life support) system; instrument panels; overhead hatch/docking port; forward EVA hatch; sixteen Reaction Control System (RCS) thrusters (identical to those used on the Service Module) mounted in four quads; rendezvous radar; VHF and S-band communications equipment and antennas; guidance and navigation systems (primary and backup); active thermal control system (an ice sublimator); Ascent Propulsion System (APS) engine; and enough fuel, battery power, cooling water, and breathing oxygen to return to lunar orbit and rendezvous with the Apollo Command/Service Module. The ascent stage also carried lunar rock and soil samples back with the crew, as much as 238 pounds (108 kg) on Apollo 17.

Crew: 2
Crew cabin volume: 235 cubic feet (6.7 m3)
Height: 9.29 feet (2.83 m)
Width: 14.08 feet (4.29 m)
Depth: 13.25 feet (4.04 m)
Mass including fuel: 10,300 pounds (4,700 kg)
Atmosphere: 100% oxygen at 4.8 pounds per square inch (33 kPa)
Water: two 42.5-pound (19.3 kg) storage tanks
Coolant: 25 pounds (11 kg) of ethylene glycol/water solution
Thermal Control: one active water-ice sublimator
RCS propellant mass: 633 pounds (287 kg)
RCS thrusters: sixteen x 100 pounds-force (440 N) in four quads
RCS propellants: Aerozine 50 fuel / nitrogen tetroxide(N2O4) oxidizer
RCS specific impulse: 290 sec (2,840 N-sec/kg)
APS propellant mass: 5,187 pounds (2,353 kg)
APS engine: Rocketdyne RS-18 [10]
APS thrust: 3,500 pounds-force (16,000 N)
APS propellants: Aerozine 50 fuel / nitrogen tetroxide oxidizer
APS pressurant: two 6.4-pound (2.9 kg) helium tanks at 3,000 pounds per square inch (21 MPa)
APS specific impulse: 311 sec (3,050 N-sec/kg)
APS delta-V: 7,280 feet per second (2,220 m/s)
Thrust-to-weight ratio at liftoff: 2.124 (in lunar gravity)
Batteries: two 28-32 volt, 296 ampere-hour silver-zinc batteries; 125 pounds (57 kg) each
Power: 28 V DC, 115 V 400 Hz AC

Descent stage:

The Descent stage contained the landing gear; EVA ladder; landing radar; Descent Propulsion System (DPS) engine and fuel to land on the Moon. It had several cargo compartments with replacement Portable Life Support System (PLSS) batteries and lithium hydroxide canisters; the Apollo Lunar Surface Experiment Package ALSEP; Mobile Equipment Cart (a hand-pulled equipment cart used on Apollo 14) or the Lunar Rover (used on Apollo 15-17); deployable S-band antenna (Apollo 11-14); surface television camera; surface tools; and lunar sample collection boxes. The descent stage carried consumables for the lunar stay: batteries; oxygen and water for drinking and cooling. The No. 1 landing gear leg carried an aluminum plaque near the ladder commemorating each landing flight, listing the names of the astronauts, and in the case of the first and last, the President of the United States (Richard M. Nixon).

Height minus landing probes: 8.59 feet (2.62 m)
Width/depth minus landing gear: 12.83 feet (3.91 m)
Width/depth incl. landing gear: 31.0 feet (9.4 m)
Mass including fuel: 22,783 pounds (10,334 kg)
Water: one 151-kilogram (330 lb) storage tank
DPS propellant mass: 18,000 pounds (8,200 kg)
DPS thrust: 10,125 pounds-force (45,040 N), throttleable between 10% and 60% of full thrust
DPS propellants: Aerozine 50/nitrogen tetroxide
DPS pressurant: one 49-pound (22 kg) supercritical helium tank at 1,555 pounds per square inch (10.72 MPa)
DPS specific impulse: 311 sec (3,050 N-sec/kg)
DPS delta-V: 8,100 feet per second (2,500 m/s)
Batteries: four (Apollo 9-14) or five (Apollo 15-17) 28-32 V, 415 A·h silver-zinc batteries; 135 pounds (61 kg) each

15 Lunar modules were produced, and 5 of these were not flown. The last 3 were intended for missions which were cancelled - i.e. after Apollo 17.

LM-2 was intended for an unmanned flight test, but never flown.

LM-9 was intended to be for Apollo 15, but the mission parameters were changed from an "H" to a "J" mission, which required a longer stay and revised LM design.