|
About the Lunar Module
The Lunar Module was a fantastic vehicle! Some might consider it ugly, even primitive looking with its dangling legs and disjointed appearance, but I think it is one of the most beautiful and important machines ever built by human hands.
The Lunar Module was designed specifically for the purpose of landing humans on the Moon and it performed that task to near perfection.
It is the first true crewed spaceship in the sense that it was made for space flight and lunar landings exclusively. This is the reason for its angular, non-aerodynamic shape (no wind resistance in space).
Weight was a major factor on the Moon missions so the Lunar Module was an extremely thrifty, no frills creation. Some of its walls were not much thicker than a sheet of paper.
A total of six Lunar Modules landed on the Moon, delivering 12 Moonwalkers (Apollo missions: 11,12,14,15,16,17).
It was built by Grumman and originally called the Lunar Excursion Module. The name was changed to Lunar Moduled but the shortened "LEM" nickname was still used.
During Earth launch the LEM was stored beneath the Command and Service Modules which housed the three-man crew. Once on their way to the Moon, the Command Module pilot would ease forward, come about and then dock with the LEM. The joined vehicles would then make the rest of the journey to the Moon.
Once in lunar orbit, two astronauts would enter the LEM and then undock from the Command Module to head for the landing site. The command module pilot remained in lunar orbit aboard the Command and Service Modules. The two astronauts aboard the LEM stood during their entire flight.
After the landing and explorations were complete, the two astronauts would return to lunar orbit and once again dock with the Command Module. Only the ascent stage (the top half) would leave the Moon. The descent stage remained on the surface. After rejoining the Command Module pilot, the two Moonwalkers would return to the Command Module. The ascent stage of the LEM would be jettisoned prior to re-entry and splashdown.
Guy Harrison
A Detailed Description of the LEM
courtesy NASA
The lunar module was a two-stage vehicle designed for space operations near and on the Moon. The spacecraft mass of 16,448 kg was the mass of the LM including astronauts, expendables, and approximately 12,000 kg of propellants. The fully fueled mass of the ascent stage was about 4985 kg and the descent stage 11,463 kg. 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 dock-ing 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 served as a platform for launching the ascent stage and was left behind on 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 cu-bic 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 assem-blies 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 launched from the Moon at the end of lunar surface operations and returned 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 com-posed of four 450 N thrust chambers and nozzles pointing in different directions. Telemetry, TV, voice, and range com-munications 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 pro-vided 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.
Source: NASA
The Eagle Has Landed
From the Apollo 11 space-to-ground transcript:
EAGLE: 540 feet, down at 30 [feet per second] . . . down at 15 . . . 400 feet down at 9 . . . forward . . . 350 feet, down at 4 . . . 300 feet, down 3 1/2 . . . 47 forward . . . 1 1/2 down . . . 13 forward . . . 11 forward? coming down nicely . . . 200 feet, 4 1/2 down . . . 5 1/2 down . . . 5 percent . . . 75 feet . . . 6 forward . . . lights on . . . down 2 1/2 . . . 40 feet? down 2 1/2, kicking up some dust . . . 30 feet, 2 1/2 down . . . faint shadow . . . 4 forward . . . 4 forward . . . drifting to right a little . . . O.K. . . .
HOUSTON: 30 seconds [fuel remaining].
EAGLE: Contact light! O.K., engine stop . . . descent engine command override off . . .
HOUSTON: We copy you down, Eagle.
EAGLE: Houston, Tranquility Base here. The Eagle has landed!
HOUSTON: Roger, Tranquility. We copy you on the ground. You've got a bunch of guys about to turn blue. We're breathing again. Thanks a lot.
TRANQUILITY: Thank you . . . That may have seemed like a very long final phase. The auto targeting was taking us right into a football-field-sized crater, with a large number of big boulders and rocks for about one or two crater-diameters around it, and it required flying manually over the rock field to find a reasonably good area.
HOUSTON: Roger, we copy. It was beautiful from here, Tranquility. Over.
TRANQUILITY: We'll get to the details of what's around here, but it looks like a collection of just about every variety of shape, angularity, granularity, about every variety of rock you could find.
HOUSTON: Roger, Tranquility. Be advised there's lots of smiling faces in this room, and all over the world.
The photo at at top of the page is the Eagle, Apollo 11's lunar module (NASA). At right above is a photo of the cockpit of the lunar module on display at the Smithsonian Air and Space Musuem in Washington D.C. (Smithsonian)
   
|
|
