The Apollo Lunar Module, Explained by NASA's Apollo Digest

NASA's Apollo Digest film series explained the Apollo spacecraft to the public, using period animation. This episode tours the lunar module (LM), the vehicle that would take two astronauts and their scientific instruments down to the Moon, serve as their command post and communications center on the surface, and carry them back up to the orbiting command module for the trip home.

Two spacecraft in one

• The descent stage, the lower half, lowers the vehicle to a soft landing and later becomes the launch platform for leaving the Moon.
• The ascent stage, the upper half, holds the crew compartment and flight controls. When exploration is over, it separates from the descent stage and flies the astronauts up to meet the command module.

A docking hatch on top joins the LM to the command module and lets the crew move between the two. A small window beside it has one job: giving the pilot a view during the critical docking after the return from the Moon. The main hatch, in the lower front of the ascent stage, is the astronauts' way out onto the surface.

Communications

The LM carries 13 antennas for its various modes of receiving and transmitting. A dish-shaped antenna serves as the rendezvous radar, used to find and dock with the command module after leaving the Moon.

Propulsion

• Attitude control: four clusters of four small rocket engines each let the pilot move the spacecraft up, down, forward, back or sideways to position it near the surface.
• Descent engine: in the lower part of the module, it powers the descent. Its thrust can be throttled from one to more than 10,000 pounds.
• Landing radar: mounted near the skirt of the descent engine, it feeds altitude, range and speed to the crew during the landing.

Inside

Most of the cabin is taken up by instruments, dials and gauges. The commander's center panel carries the main flight controls, some like those in the command module, and during the slow descent its gauges show thrust and altitude. A computer keyboard gives instant information on the flight and the spacecraft's performance when the crew enters coded words. The pilot also has thrust and attitude controls, a center panel of instruments and switches, and the abort guidance panel, which shows the state of every system and, if something goes wrong, the best procedure to follow.

Sources

• NASA Image and Video Library: "Apollo Digest Series: The Lunar Module," a NASA film. The narration is rewritten in hubnx's own words.