Instrument Host Overview
   ========================
     The Apollo 14 Lunar Surface Experiments Package (ALSEP) was carried
     on the Apollo 14 lunar module spacecraft.  It contained scientific
     experiments to be deployed and left on the lunar surface, and other
     scientific and sample collection apparatus.  The ALSEP central
     station located at 3.6440 S latitude, 17.4775 W longitude
     [DAVIES&COLVIN2000], was turned on at 17:23 UT on 5 February 1971 and
     shut down along with the other ALSEP stations on 30 September 1977.
     For more information, see the ALSEP termination report by Bates et.
     al (1979) [BATESETAL1979].
 
     ALSEP consisted of a set of scientific instruments emplaced near the
     Apollo 14 landing site by the astronauts.  The instruments were
     arrayed around a central station which supplied power to run the
     instruments and communications so data collected by the experiments
     could be relayed to Earth.  The central station was a 25 kg box with
     a stowed volume of 34,800 cubic cm.  Thermal control was achieved by
     passive elements (insulation, reflectors, thermal coatings) as well
     as power dissipation resistors and heaters.  Communications with
     Earth were achieved through a 58 cm long, 3.8 cm diameter modified
     axial-helical antenna mounted on top of the central station and
     pointed towards Earth by the astronauts.  Transmitters, receivers,
     data processors and multiplexers were housed within the central
     station.  Data collected from the instruments were converted into a
     telemetry format and transmitted to Earth.  The ALSEP system and
     instruments were controlled by commands from Earth.  The uplink
     frequency for all Apollo mission ALSEP's was 2119 MHz, the downlink
     frequency for the Apollo 14 ALSEP was 2279.5 MHz.
 
     A radioisotope thermoelectric generator (RTG, SNAP-27 model) provided
     the power to run the ALSEP operations.  The generator consisted of a
     46 cm high central cylinder and eight radiating rectangular fins with
     a total tip-to-tip diameter of 40 cm.  The central cylinder had a
     thinner concentric inner cylinder inside, and the two cylinders were
     attached along their surfaces by 442 spring-loaded lead-telluride
     thermoelectric couples mounted radially along the length of the
     cylinders. The generator assembly had a total mass of 17 kg.  The
     power source was an approximately 4 kg fuel capsule in the shape of a
     long rod which contained plutonium-238 and was placed in the inner
     cylinder of the RTG by the astronauts on deployment.  Plutonium-238
     decays with a half-life of 89.6 years and produces heat.  This heat
     would conduct from the inner cylinder to the outer via the
     thermocouples which would convert the heat directly to electrical
     power.  Excess heat on the outer cylinder would be radiated to space
     by the fins. The RTG produced approximately 70 W DC at 16 V. (63.5 W
     after one year.)  The electricity was routed through a cable to a
     power conditioning unit and a power distribution unit in the central
     station to supply the correct voltage and power to each instrument.
 
 
     ALSEP Scientific Instruments
     ----------------------------
       All ALSEP instruments were deployed on the surface by the
       astronauts and attached to the central station by cables.  The
       Apollo 14 ALSEP instruments consisted of: (1) a passive
       seismometer, designed to measure seismic activity and physical
       properties of the lunar crust and interior; (2) an active
       seismometer to study the physical properties of lunar surface and
       subsurface materials and the structure of the local near-surface
       layers; (3) a suprathermal ion detector, designed to measure the
       flux composition, energy, and velocity of low-energy positive ions;
       (4) a charged particle lunar environment experiment, designed to
       measure particle energies of solar protons and electrons that reach
       the lunar surface; (5) a cold cathode ion gauge, designed to
       measure the atmosphere and any variations with time or solar
       activity such atmosphere may have; and (6) a lunar dust detector,
       to measure dust accumulation, radiation damage to solar cells, and
       reflected infrared energy and temperatures.  See the Apollo 14
       preliminary science report (1970) [APOLLO14A1971] for more information
       about the ALSEP experiments.
 
   This instrument host description was provided by the NSSDC.