Apollo 12 Command and Service Module (CSM)

Description

Apollo 12 was the second mission in which humans walked on the lunar surface and returned to Earth. On 19 November 1969 two astronauts (Apollo 12 Commander Charles P. "Pete" Conrad and LM Pilot Alan L. Bean) landed in Oceanus Procellarum (Ocean of Storms) on the Moon in the Lunar Module (LM) while the Command and Service Module (CSM) (with CM pilot Richard F. Gordon) continued in lunar orbit. During their stay on the Moon, the astronauts set up scientific experiments, took photographs, examined the nearby Surveyor 3 spacecraft which had landed on the Moon 2 1/2 years earlier and removed pieces for later examination on Earth, and collected lunar samples on two moonwalk EVA's. The LM took off from the Moon on 20 November and the astronauts returned to Earth on 24 November.

Mission Profile

Launch took place under cloudy, rain-swept skies on Saturn V SA-507 on 14 November 1969 at 16:22:00 UT (11:22:00 a.m. EST) from Pad 39A at Kennedy Space Center. The spacecraft was struck by lightning 36 seconds after launch and again 52 seconds after launch, which momentarily shut off electrical power and cut out telemetry contact. Power was automatically switched to battery backup while the crew resored the primary power system. There were no further problems with the power system and the spacecraft entered planned Earth parking orbit at 11 minutes 44 seconds after liftoff. After 1 1/2 orbits the S-IVB stage was re-ignited at 19:15:14 UT for a translunar injection burn of 5 min. 45 sec. putting the spacecraft on course for the Moon. The CSM separated from the S-IVB stage containing the LM 25 minutes later, turned around and docked with the LM at 19:48:53 UT. The S-IVB stage was then jettisoned into Earth orbit instead of planned heliocentric orbit due to error in the instrument unit. During lunar coast, the LM was checked out to ensure no electrical damage had been caused by the lightning. A midcourse correction was made on 16 November at 02:15 UT. A six minute SPS burn on 18 November at 03:47:23 UT put the Apollo 12 into lunar orbit. Two orbits later a second burn circularized the orbit. Conrad and Bean entered the LM and it separated from the CSM at 04:16:03 UT on 19 November. The LM descent engine fired for 29 seconds at 05:47 UT, and the LM landed in Oceanus Procellarum near the rim of Surveyor crater at 06:54:35 UT. Conrad and Bean performed two surface EVA's, one on 19 November and one on 20 November, during which an Apollo lunar surface experiments package (ALSEP) was placed on the lunar surface, 34.35 kg of samples of the lunar terrain were acquired, various photographs were exposed by the astronauts during lunar surface activities, and parts were taken from the Surveyor 3 spacecraft for examination.

The LM lifted off from the Moon on 20 November at 14:25:47 UT after 31 hours 31 minutes on the lunar surface. After docking with the CSM at 17:58:22 UT, the LM was jettisoned at 20:21:30 and intentionally crashed into the Moon creating the first recorded artificial moonquake. Transearth injection began at 20:49:16 UT on 21 November with a firing of the CSM main engine. A mid-course correction was made on 22 November. The CM separated from the SM on 24 November at 20:29:21. Apollo 12 splashed down in the Pacific Ocean on 24 November 1969 at 20:58:24 UT (3:58:24 p.m. EST) after a mission elapsed time of 244 hrs, 36 mins, 24 secs. The splashdown point was 15 deg 47 min S, 165 deg 9 min W, near American Samoa and 6.9 km (4.3 mi) from the recovery ship USS Hornet.

Performance of the spacecraft, the first of the Apollo H-series missions, was very good for all aspects of the mission. The primary mission goals of an extensive series of lunar exploration tasks, deployment of the ALSEP, and demonstration of the ability to remain and work on the surface of the Moon for an extended period were achieved. Conrad was a Navy Commander on his third spaceflight (previously on Gemini's 5 and 11, later to fly on Skylab 2), Bean was a Navy Lt. Commander on his first flight (he later flew on Skylab 3), and Gordon was a Navy Commander on his second flight (Gemini 11). The backup crew for this mission was David Scott, Alfred Worden, and James Irwin. The Apollo 12 Command Module "Yankee Clipper" is on display at the Virginia Air and Space Center in Hampton, Virginia. The returned Surveyor 3 camera is on display at the Smithsonian Air and Space Museum in Washington, D.C.

Spacecraft and Subsystems

As the name implies, the Command and Service Module (CSM) was comprised of two distinct units: the Command Module (CM), which housed the crew, spacecraft operations systems, and re-entry equipment, and the Service Module (SM) which carried most of the consumables (oxygen, water, helium, fuel cells, and fuel) and the main propulsion system. The total length of the two modules attached was 11.0 meters with a maximum diameter of 3.9 meters. Block II CSM's were used for all the crewed Apollo missions. The Apollo 12 CSM mass of 28,790 kg was the launch mass including propellants and expendables, of this the Command Module (CM 108) had a mass of 5609 kg and the Service Module (SM 108) 23,181 kg.

Telecommunications included voice, television, data, and tracking and ranging subsystems for communications between astronauts, CM, LM, and Earth. Voice contact was provided by an S-band uplink and downlink system. Tracking was done through a unified S-band transponder. A high gain steerable S-band antenna consisting of four 79-cm diameter parabolic dishes was mounted on a folding boom at the aft end of the SM. Two VHF scimitar antennas were also mounted on the SM. There was also a VHF recovery beacon mounted in the CM. The CSM environmental control system regulated cabin atmosphere, pressure, temperature, carbon dioxide, odors, particles, and ventilation and controlled the temperature range of the electronic equipment.

Command Module

The CM was a conical pressure vessel with a maximum diameter of 3.9 m at its base and a height of 3.65 m. It was made of an aluminum honeycomb sandwhich bonded between sheet aluminum alloy. The base of the CM consisted of a heat shield made of brazed stainless steel honeycomb filled with a phenolic epoxy resin as an ablative material and varied in thickness from 1.8 to 6.9 cm. At the tip of the cone was a hatch and docking assembly designed to mate with the lunar module. The CM was divided into three compartments. The forward compartment in the nose of the cone held the three 25.4 m diameter main parachutes, two 5 m drogue parachutes, and pilot mortar chutes for Earth landing. The aft compartment was situated around the base of the CM and contained propellant tanks, reaction control engines, wiring, and plumbing. The crew compartment comprised most of the volume of the CM, approximately 6.17 cubic meters of space. Three astronaut couches were lined up facing forward in the center of the compartment. A large access hatch was situated above the center couch. A short access tunnel led to the docking hatch in the CM nose. The crew compartment held the controls, displays, navigation equipment and other systems used by the astronauts. The CM had five windows: one in the access hatch, one next to each astronaut in the two outer seats, and two forward-facing rendezvous windows. Five silver/zinc-oxide batteries provided power after the CM and SM detached, three for re-entry and after landing and two for vehicle separation and parachute deployment. The CM had twelve 420 N nitrogen tetroxide/hydrazine reaction control thrusters. The CM provided the re-entry capability at the end of the mission after separation from the Service Module.

Service Module

The SM was a cylinder 3.9 meters in diameter and 7.6 m long which was attached to the back of the CM. The outer skin of the SM was formed of 2.5 cm thick aluminum honeycomb panels. The interior was divided by milled aluminum radial beams into six sections around a central cylinder. At the back of the SM mounted in the central cylinder was a gimbal mounted re-startable hypergolic liquid propellant 91,000 N engine and cone shaped engine nozzle. Attitude control was provided by four identical banks of four 450 N reaction control thrusters each spaced 90 degrees apart around the forward part of the SM. The six sections of the SM held three 31-cell hydrogen oxygen fuel cells which provided 28 volts, two cryogenic oxygen and two cryogenic hydrogen tanks, four tanks for the main propulsion engine, two for fuel and two for oxidizer, and the subsystems the main propulsion unit. Two helium tanks were mounted in the central cylinder. Electrical power system radiators were at the top of the cylinder and environmental control radiator panels spaced around the bottom.

Apollo Program

The Apollo program included a large number of uncrewed test missions and 12 crewed missions: three Earth orbiting missions (Apollo 7, 9 and Apollo-Soyuz), two lunar orbiting missions (Apollo 8 and 10), a lunar swingby (Apollo 13), and six Moon landing missions (Apollo 11, 12, 14, 15, 16, and 17). Two astronauts from each of these six missions walked on the Moon (Neil Armstrong, Edwin Aldrin, Charles Conrad, Alan Bean, Alan Shepard, Edgar Mitchell, David Scott, James Irwin, John Young, Charles Duke, Gene Cernan, and Harrison Schmitt), the only humans to have set foot on another solar system body. Total funding for the Apollo program was approximately $20,443,600,000.

For information on the Lunar Module and details of activities on the lunar surface, see:

http://nssdc.gsfc.nasa.gov/database/MasterCatalog?sc=1969-099C