Apollo 16 Command and Service Module Instrument Host Overview ======================== The Apollo 16 Command and Service Module (CSM) orbited the moon during the Apollo 16 mission. It was piloted by Thomas K. Mattingly, II. 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 launch mass, including propellants and expendables, of the Apollo 16 CSM was 30,354 kg of which the Command Module (CM-113) had a mass of 5840 kg and the Service Module (SM-113) 24,514 kg. The Apollo 16 CM was named 'Casper'. 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 meters at its base and a height of 3.65 meters. It was made of an aluminum honeycomb sandwich 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 meters diameter main parachutes, two 5 meter 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 meters 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. Environmental control radiator panels were spaced around the top of the cylinder and electrical power system radiators near the bottom. The SM carried the Apollo 16 subsatellite spacecraft, a small satellite released into lunar orbit during the mission to study the plasma, particle, and magnetic field environment of the Moon and map the lunar gravity field. Scientific Experiments ---------------------- The following scientific experiments were performed on board the Apollo 16 Command and Service Module: - The Handheld Photography Experiment included Hasselblad and Maurer cameras that were used (1) to obtain photographs of the transposition, docking, lunar module ejection maneuver, and LM rendezvous sequence from both the command and lunar modules, (2) to obtain photographs of the lunar ground track and of future landing sites, (3) to record the operational activities of the crew, (4) to obtain long-distance earth and lunar photographs for areas of scientific interest, and (5) to obtain photos of lunar surface features and of the activities of the astronauts after their landing on the Moon. - The Panoramic Photography Experiment obtained high-resolution panoramic photographs with stereoscopic and monoscopic coverage of the lunar surface using a panoramic camera. - The Metric Photography Experiment obtained high-quality metric photographs of the lunar surface and stellar photographs exposed simultaneously with the metric photographs. - The Mapping Camera Aspect Stellar Photography was part of the mapping camera subsystem, which provided cartographic pointing references for the metric camera through the use of the star field photographed. - The Laser Altimeter Experiment obtained data on the altitude of the CSM above the lunar surface to support mapping and panoramic camera photography, to provide altitude data for other orbital experiments, and to relate lunar topographical features for a better definition of lunar shape. - The UV Photography Experiment obtained ultraviolet photographs of the Earth and Moon for comparison with similar photographs of Mars and Venus for atmospheric and surface studies. - The Gegenschein Experiment photographed the reflection from dust particles at the Moulton point to determine the contribution of such reflections to the gegenschein. This experiment did not yield any data because of pointing errors. - The Gamma-Ray Spectrometer Experiment conducted a geochemical mapping of the lunar surface by observing emitted gamma radiation. - The X-Ray Fluorescence Spectrometer Experiment was used for orbital mapping of the lunar surface composition and X-ray galactic observations during the transearth coast. - The Alpha Particle Spectrometer Experiment determined the lunar surface radon evolution and identified localized sources of enhanced radon emission that may correspond to regions of enhanced lunar outgassing. - The S-Band Transponder Experiment measured the lunar gravitational field by observing the dynamical motion of the spacecraft in free fall orbits to provide information about the distribution of lunar mass. - The Window Meteoroid Detector Experiment used the CM heat shield window surfaces (fused silica) to obtain information about the flux of meteoroids with masses of 1 nanogram or less. About 0.4 square meters of the window surfaces were used as meteoroid impact detectors. - The Mass Spectrometer Experiment measured the composition of the ambient lunar atmosphere for studying source, sink, and transport mechanisms. - The Down-Link Bistatic Radar Experiment utilized the S-band (13-cm) and very high frequency (VHF, 116-cm) transmitters on the CSM. Radio signals reflected from the lunar surface were received at the earth to derive quantitative inferences about the Moon. - The Skylab-Apollo Contamination Photography Experiment consisting of several different cameras to 1) map the scattering function of visible light produced by any residual cloud around the CSM and 2) to study the dynamics of particles which occurred during a dump of liquids and also to determine the decay of background brightness resulting from these dumps. - The Biostack Experiment used a hermetically sealed aluminum container containing a series of monolayers of selected biologic material to study the effects of high-energy/high-Z particles on a broad spectrum of biologic systems from the molecular to the highly organized and developed forms of life. For more information about the CSM and its experiments, see the Apollo 16 Preliminary Science Report (1972) and the Apollo - Expedition to Descartes mission report (1972). References ========== Apollo 16 Preliminary Science Report, NASA SP-315, published by NASA, Washington, D.C., 1972. Apollo 16 - Expedition to Descartes (mission report), NASA MR-11, published by NASA, Washington, D.C., 1972.