Instrument Host Overview
  ========================
    The Apollo 15 lunar module (LM) 'Falcon' was the fourth crewed
    vehicle to land on the Moon.  It carried two astronauts, Commander
    David R. Scott and LM pilot James B. Irwin, the seventh and eighth 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 apparatus.  The experiments
    performed on the Moon, in addition to the ALSEP suite, were geologic
    sample collection, surface photography, soil mechanics investigations
    to study physical properties of the lunar regolith, and the solar wind
    composition experiment which collected samples of solar wind particles
    for return to Earth.
 
    The LM separated from the Command and Service Module (CSM) at 18:13:30
    UT and landed at 22:16:29 UT (6:16:29 p.m. EDT) on 30 July 1971 in the
    Mare Imbrium region at the foot of the Apennine mountain range at
    26.1322 N latitude, 3.6339 E longitude (IAU Mean Earth Polar Axis
    coordinate system [DAVIES&COLVIN2000]).  Scott and Irwin made three
    moonwalk extra-vehicular activities (EVAs) totaling 18 hours, 35
    minutes. During this time they covered 27.9 km and collected 77.31 kg
    of rock and soil samples.  The LRV was used to explore regions within 5
    km of the LM landing site. This was the first time a vehicle of this
    type had been used, and its performance on the lunar terrain was very
    successful.  Two hours after landing the cabin was depressurized and
    Scott performed a standup EVA for 33 minutes, describing and
    photographing the surrounding terrain from the LM upper hatch.
 
    The first moonwalk EVA was on 31 July from 13:13:10 UT to 19:45:59 UT,
    during which time the LRV was unloaded, deployed, and driven.
    Photographs of the lunar surface were taken and geologic samples were
    collected from the LM site and during the three geological traverses.
    The traverse on the first EVA covered 10.3 km to the edge of Hadley
    Rille to Elbow Crater and near St. George Crater and back to the LM,
    where a core sample was taken from three meters below the surface.  The
    ALSEP was deployed at the end of the traverse.  On the second EVA, on 1
    August from 11:48:48 UT to 19:01:02 UT, the LRV was driven on a 12.5 km
    traverse southeast along the base of the Apennine Mountains near Index,
    Arbeit, Crescent, Dune, and Spur craters and back to the ALSEP site.
    On the third EVA on 2 August from 08:52:14 UT to 13:42:04 UT the LRV
    was driven a total of 5.1 km west to Scarp Crater and northwest along
    the edge of Hadley Rille and back east across the mare.  After the
    final EVA Scott performed a televised demonstration of a hammer and
    feather falling at the same rate in the lunar vacuum.  The astronauts
    also left a plaque and small figure on the surface in memory of all
    fourteen American and Soviet space explorers who had died during the
    two nation's space programs.
 
    The LM lifted off the Moon on 2 August at 17:11:22 UT after 66 hours,
    55 minutes on the lunar surface.  After docking with the CSM (piloted
    by Alfred M. Worden) at 19:09:47 UT, the LM was jettisoned on 3 August
    at 01:04:14 UT and impacted on the Moon 2 hours later (03:03:37.0 UT)
    at 26.36 N, 0.25 E, 93 km west of the Apollo 15 ALSEP site, with an
    estimated impact velocity of 1.7 km/s at an angle of about 3.2 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 16,434 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 4971 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 command and service module (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.
 
 
    Scientific Experiments
    ----------------------
      The following scientific experiments were performed on board or at
      the Apollo 15 Lunar Module:
 
      - Handheld Photography documented the deployment of experiments,
        augmented crew observations and descriptions of the lunar
        traverses, and recorded the effects of the interaction between
        Apollo equipment and the lunar surface.
 
      - The Soil Mechanics Experiment studied the properties of the lunar
        soil.
 
      - The Solar Wind Composition Experiment collected samples of the
        solar wind for analysis on Earth.
 
      - 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.
 
    For more information about the lunar module and its experiments, see
    the Apollo 15 Preliminary Science Report [APOLLO15A1972].
 
 
  This instrument host description was provided by the NASA National Space
  Science Data Center.