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SP-4012 NASA HISTORICAL DATA BOOK: VOLUME III
- PROGRAMS AND PROJECTS 1969-1978
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Figure 2-2. Apollo Lunar Module. The designers of the
Apollo lunar module (LM) could ignore the requirements for
aerodynamic streamlining demanded by vehicles that flew in or
returned through earth's atmosphere. This ungainly looking vehicle
operated only in space. The two-stage spacecraft, carried to the
vicinity of the moon docked to the Apollo command module, was
designed to land two Apollo astronauts on the moon's surface. From
lunar orbit, where it was released by the Apollo command and service
module (CSM), the LM's descent and ascent stages functioned as one
spacecraft. During their time on the surface, the crew lived in the
LM's ascent stage. When it was time to return to the waiting CSM, the
descent stage provided a launch platform for the ascent half of the
lunar module.
It took more than two years to design the LM, with its
makers, led by Grumman Aircraft Engineering Corporation, fighting
weight gain long after a configuration was approved The most
troublesome, critical, and heavy of the LM's components were its 18
engines-descent propulsion (43 900 newtons),- ascent propulsion (15
500 newtons), and 16 small attitude control engines clustered in
quads around the ascent stage. Propellant for these engines accounted
for more than 70 percent of the spacecraft's total' weight of 1500
kilograms.
The ascent stage was basically cylindrical 0.29-meter
diameter, 3.75-meter height), but with angular faces. its aluminum
skin was encased by a Mylar thermal-micrometeorite shield, The
cruciform structure of the descent stage supported the descent engine
and its 4 fuel tanks. Four legs (maximum diameter 9.45 meters), the
struts of which were filled with crushable aluminum honeycomb ,for
absorbing the shock of landing, were capped by footpads. The descent
stage (3.23 meters high) was also constructed of aluminum alloy. A
ladder attached to one of the legs gave the crew access to the
surface. A docking tunnel (0. 81-meter diameter) was provided for
crew transfer between the command module and the LM ascent stage.
After the surface operations were completed and the crew returned via
the ascent stage to the CSM, the LM was jettisoned. A LM was included
on a manned Apollo mission for the first time in March 1969 (Apollo
9). For more information on spacecraft systems, see volume 2, table
2-55.
Source: JSC, "Apollo Program Summary Report," JSC-09423,
Apr. 1975, p. 4-58.
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