Apollo 16 Command and Service Module (CSM)

Description

Apollo 16 was the fifth mission in which humans walked on the lunar surface and returned to Earth. On 21 April 1972 two astronauts (Apollo 16 Commander John W. Young and LM pilot Charles M. Duke, Jr.) landed in the Descartes region of the Moon in the Lunar Module (LM) while the Command and Service Module (CSM) (with CM pilot Thomas K. Mattingly, II) continued in lunar orbit. During their stay on the Moon, the astronauts set up scientific experiments, took photographs, and collected lunar samples. The LM took off from the Moon on 24 April and the astronauts returned to Earth on 27 April.

Mission Profile

Apollo 16 launched on 16 April 1972 at 17:54:00 (12:54:00 p.m. EST) on Saturn V SA-511 from Pad 39A at Kennedy Space Center. (The launch was postponed from the originally scheduled date, March 17, because of a docking ring jettison malfunction.) The spacecraft entered Earth parking orbit at 18:05:56 UT and translunar injection took place at 20:27:37 UT. The CSM and S-IVB stage separated at 20:58:59 UT and CSM-LM docking was achieved at 21:15:53 UT. The S-IVB stage was released into a lunar impact trajectory, but due to an earlier problem with the auxiliary propulsion system (APS) helium regulators, which resulted in continuous venting and loss of helium, the second APS burn could not be made. Tracking of the S-IVB was lost on 17 April at 21:03 UT due to a transponder failure. (The S-IVB stage impacted the Moon on 19 April at 21:02:04 UT at 1.3 N, 23.8 W with a velocity of 2.5 to 2.6 km/s at a 79 degree angle from the horizontal, as estimated from the Apollo 12, 14 and 16 seismic station data.) A mid-course correction was performed at 00:33:01 UT on 18 April. During translunar coast a CSM navigation problem was discovered in which a false indication would cause loss of inertial reference, this was solved by a real-time change in the computer program. The SIM door was jettisoned on 19 April at 15:57:00 UT and lunar orbit insertion took place at 20:22:28 UT. Two revolutions later the orbit was lowered to one with a perilune of 20 km.

At 15:24 UT on 20 April Young and Duke entered the LM. The LM separated from the CSM at 18:08:00 UT, but the LM descent was delayed almost 6 hours due to a malfunction in the yaw gimbal servo loop on the CSM which caused oscillations in the service propulsion system (SPS). Engineers determined that the problem would not seriously affect CSM steering and the miision was allowed to continue with the LM descent. The LM landed at 02:23:35 UT on 21 April in the Descartes highland region just north of the crater Dolland at 9.0 S, 15.5 E. Young and Duke made three moonwalk EVAs totaling 20 hours, 14 minutes. During this time they covered 27 km using the Lunar Roving Vehicle, collected 95.71 kg of rock and soil samples, took photographs, and set up the ALSEP and other scientific experiments. Other experiments were also performed from orbit in the CSM during this time.

The LM lifted off from the Moon at 01:25:48 UT on 24 April after 71 hours, 2 minutes on the lunar surface. After the LM docked with the CSM at 03:35:18 UT the lunar samples and other equipment were transferred from the LM and the LM was jettisoned at 20:54:12 UT on 24 April. The LM began tumbling, apparently due to an open circuit breaker in the guidance and navigation system. As a result the planned deorbit and lunar impact could not be attempted. The LM remained in lunar orbit with an estimated lifetime of one year. The instrument boom which carried the orbital mass spectrometer would not retract and was jettisoned. Because of earlier problems with the SPS yaw gimbal servo loop the mission was shortened by one day. The orbital shaping maneuver was cancelled, and the subsatellite was spring-launched at 21:56:09 UT into an elliptical orbit with a lifetime of one month, rather than the planned one-year orbit. Transearth injection began at 02:15:33 UT on 25 April. On 25 April at 20:43 UT Mattingly began a cislunar EVA to retrieve camera film from the SIM bay and inspect instruments, two trips taking a total of 1 hour, 24 minutes. The CM separated from the SM on 27 April at 19:16:33 UT. Apollo 16 splashed down in the Pacific Ocean on 27 April 1972 at 19:45:05 UT (2:45:05 p.m. EST) after a mission elapsed timeof 265 hrs, 51 mins, 5 secs. The splashdown point was 0 deg 43 min S, 156 deg 13 min W, 215 miles southeast of Christmas Island and 5 km (3 mi) from the recovery ship USS Ticonderoga.

Performance of the spacecraft, the second of the Apollo J-series missions, was good for most aspects of the mission. The primary mission goals of inspecting, surveying, and sampling materials in the Descartes region, emplacement and activation of surface experiments, conducting inflight experiments and photographic tasks from lunar orbit, engineering evaluation of spacecraft and equipment, and performance of zero-gravity experiments were achieved despite the mission being shortened by one day. Young, 41, was a Navy Captain who had flown on three previous spaceflights (Gemini 3, Gemini 10, and Apollo 10; he later flew on STS-1 and STS-9), Mattingly, 36, was a Navy lt. commander on his first spaceflight (he later flew STS-4 and STS-51C), and Duke, 36, was an Air Force lt. colonel also on his first spaceflight. The backup crew for this mission was Fred Haise, Stuart Roosa, and Edger Mitchell. The Apollo 16 Command Module "Casper" is on display at the Alabama Space and Rocket Center in Huntsville, Alabama.

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. Apollo 16 was the second of the Apollo J-series spacecraft. The CSM mass of 30,354 kg was the launch mass including propellants and expendables, of this the Command Module (CM-113) had a mass of 5840 kg and the Service Module (SM-113) 24,514 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, an auxiliary battery, three cryogenic oxygen and three cryogenic hydrogen tanks, four tanks for the main propulsion engine, two for fuel and two for oxidizer, the subsystems the main propulsion unit, and a Scientific Instrument Module (SIM) bay which held a package of science instruments and cameras to be operated from lunar orbit and a small subsatellite to be put into lunar orbit. 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=1972-031C