Apollo 17 Lunar Module Instrument Host Overview ======================== The Apollo 17 Lunar Module (LM) 'Challenger' was the sixth and last crewed vehicle to land on the Moon as part of NASA's Apollo program. It carried two astronauts, Eugene A. Cernan and LM pilot Harrison H. Schmitt, the eleventh and twelfth men to walk on the Moon. The LM also carried a Lunar Roving Vehicle (LRV), an Apollo Lunar Surface Experiments Package (ALSEP) that contained scientific experiments to be deployed and left on the lunar surface, and other scientific and sample collection apparatuses. The experiments performed on the Moon, in addition to the ALSEP suite, were geologic sample collection, surface photography, gravitation acceleration measurements at the lunar surface, and soil mechanics. The LM separated from the Command and Service Module (CSM) at 17:20:56 UT on 11 December 1972 and landed on the Moon at 19:54:57 UT on 11 December 1972, on the southeastern rim of Mare Serenitatis in a valley at Taurus-Littrow at 20.19 N latitude, 30.77 E longitude (IAU Mean Earth Polar Axis coordinate system [Davies and Colvin, 2000]). Cernan and Schmitt made three moonwalk extra-vehicular activities (EVAs) totaling 22 hours, 4 minutes. During this time they covered 30 km using the Lunar Roving Vehicle, collected 110.52 kg of lunar samples, took photographs, and set up the ALSEP and performed other scientific experiments. Evans performed experiments from orbit in the CSM during this time. The Lunar Roving Vehicle (LRV) was used during EVAs to extend the range of manned lunar exploration. The first EVA was from 23:54:49 UT on 11 December to 07:06:42 UT on 12 December, during which the LRV was deployed and driven and the ALSEP was set up. During the second EVA, which began at 23:28:06 UT on 12 December and ended at 07:05:02 UT on 13 December, the astronauts deployed explosive packages for the active seismic experiment and Schmitt discovered a patch of orange soil. The third EVA involved more traverses and sample collection and lasted from 22:25:48 UT on 13 December to 05:40:56 UT on 14 December. The LM lifted off from the Moon at 22:54:37 UT on 14 December 1972 after 75 hours on the lunar surface. After the LM docked with the CSM at 01:10:15 UT on 15 December 1972 the lunar samples and other equipment were transferred from the LM and the LM was jettisoned at 04:51:31 UT. The LM impacted the Moon at 06:50:20.8 UT on 15 December 1972 at 19.96 North latitude, 30.50 East longitude, approximately 15 km from the Apollo 17 landing site, with an estimated impact velocity of 1.67 km/s at an angle ~4.9 degrees from horizontal. Lunar Module Spacecraft and Subsystems -------------------------------------- The lunar module was a two-stage vehicle designed for space operations near and on the Moon. The spacecraft mass of 16,448 kg was the mass of the LM including astronauts, expendables, and approximately 12,000 kg of propellants. The fully fueled mass of the ascent stage was about 4985 kg and the descent stage 11,463 kg. The ascent and descent stages of the LM operated as a unit until staging, when the ascent stage functioned as a single spacecraft for rendezvous and docking with the CSM. The descent stage comprised the lower part of the spacecraft and was an octagonal prism 4.2 meters across and 1.7 m thick. Four landing legs with round footpads were mounted on the sides of the descent stage and held the bottom of the stage 1.5 m above the surface. The distance between the ends of the footpads on opposite landing legs was 9.4 m. One of the legs had a small astronaut egress platform and ladder. A one meter long conical descent engine skirt protruded from the bottom of the stage. The descent stage contained the landing rocket, two tanks of aerozine 50 fuel, two tanks of nitrogen tetroxide oxidizer, water, oxygen and helium tanks and storage space for the lunar equipment and experiments, and in the case of Apollo 15, 16, and 17, the lunar rover. The descent stage served as a platform for launching the ascent stage and was left behind on the Moon. The ascent stage was an irregularly shaped unit approximately 2.8 m high and 4.0 by 4.3 meters in width mounted on top of the descent stage. The ascent stage housed the astronauts in a pressurized crew compartment with a volume of 6.65 cubic meters. There was an ingress-egress hatch in one side and a docking hatch for connecting to the CSM on top. Also mounted along the top were a parabolic rendezvous radar antenna, a steerable parabolic S-band antenna, and 2 in-flight VHF antennas. Two triangular windows were above and to either side of the egress hatch and four thrust chamber assemblies were mounted around the sides. At the base of the assembly was the ascent engine. The stage also contained an aerozine 50 fuel and an oxidizer tank, and helium, liquid oxygen, gaseous oxygen, and reaction control fuel tanks. There were no seats in the LM. A control console was mounted in the front of the crew compartment above the ingress-egress hatch and between the windows and two more control panels mounted on the side walls. The ascent stage was launched from the Moon at the end of lunar surface operations and returned the astronauts to the CSM. The descent engine was a deep-throttling ablative rocket with a maximum thrust of about 45,000 N mounted on a gimbal ring in the center of the descent stage. The ascent engine was a fixed, constant-thrust rocket with a thrust of about 15,000 N. Maneuvering was achieved via the reaction control system, which consisted of the four thrust modules, each one composed of four 450 N thrust chambers and nozzles pointing in different directions. Telemetry, TV, voice, and range communications with Earth were all via the S-band antenna. VHF was used for communications between the astronauts and the LM, and the LM and orbiting CSM. There were redundant transceivers and equipment for both S-band and VHF. An environmental control system recycled oxygen and maintained temperature in the electronics and cabin. Power was provided by 6 silver-zinc batteries. Guidance and navigation control were provided by a radar ranging system, an inertial measurement unit consisting of gyroscopes and accelerometers, and the Apollo guidance computer (AGC). Updates to the AGC in the LM were relayed by voice, then typed into the computer by an astronaut. Scientific Experiments ---------------------- The following scientific experiments were performed on board or near the Apollo 17 Lunar Module: - The Lunar Traverse Gravimeter Experiment carried on board the LRV was designed to make a high-accuracy survey of the gravitational field in the Apollo 17 landing area; - The Soil Mechanics Experiment studied the physical properties of the lunar regolith using observations recorded by video and audio; - The Surface Electrical Properties Experiment obtained data about the electromagnetic energy transmission, absorption, and reflection characteristics of the lunar surface and subsurface. - The Lunar Surface Cosmic Ray Experiment was a set of detectors hung from the LM, designed to measure solar wind particles, low energy cosmic rays, and radon; - The Neutron Probe was designed to measure the rates of low-energy neutron capture as a function of depth in the lunar regolith. - Apollo Lunar Surface Experiments Package of experiments. For more information about the LM, the LRV, and the associated experiments, see the Apollo 17 Preliminary Science Report (1973). References ========== Apollo 17 Preliminary Science Report, NASA SP-330, published by NASA, Washington, D.C., 1973. Davies, M.E., and T.R. Colvin, Lunar coordinates in the regions of the Apollo landers, Journal of Geophysical Research, Volume 105, Issue E8, pages 20,227-20,280, 2000.