PDS_VERSION_ID = PDS3
RECORD_TYPE = STREAM
LABEL_REVISION_NOTE = "E. Guinness, 1998-09-04;
J. Alexopoulos, 1999-02-01;
E. Guinness, 1999-05-10;
J. Alexopoulos, 2000-03-23"
OBJECT = INSTRUMENT_HOST
INSTRUMENT_HOST_ID = "LP"
OBJECT = INSTRUMENT_HOST_INFORMATION
INSTRUMENT_HOST_NAME = "LUNAR PROSPECTOR"
INSTRUMENT_HOST_TYPE = "SPACECRAFT"
INSTRUMENT_HOST_DESC = "
Instrument Host Overview
========================
Lunar Prospector (LP) is a small, simple, spin-stabilized spacecraft
with minimal operational requirements [BINDERETAL1998]. Its fueled
mass is 305 kg. The spacecraft bus is a graphite-epoxy drum that is
1.37 m in diameter and 1.28 m tall. Power is provided by solar
cells mounted on the surface of the bus assembly, which produce an
average of 186 w. There is also a rechargeable, 4.8 amp-hr NiCd
battery for power during night side passes. The science instruments
are mounted on three 2.5 m booms. The Gamma Ray Spectrometer is
mounted on one boom, the Neutron Spectrometer and Alpha Particle
Spectrometers are mounted on another boom, and the Magnetometer and
Electron Reflectometer are mounted on the third boom. The
Magnetometer instrument is mounted on a 1.2 m long boom extending
beyond the main boom to isolate it from the Electron Reflectometer.
The spacecraft bus houses three fuel tanks, six engines, and five
electronic units. The fuel tanks at launch hold 138 kg of hydrazine
pressurized with helium. There are two aft axial engines, two
forward axial engines, and two tangential engines.
The communication system consists of an S-band transponder, an omni
antenna with 3-pi steradian antenna pattern for uplink and downlink,
and a medium gain antenna for downlink. The engineering-only
downlink data rate is 300 bps and the science/engineering downlink
data rate is 3600 bps.
Command and control of the spacecraft is achieved by a simple
Command and Data Handling (C&DH) unit. As an individual command is
uplinked to the spacecraft, the C&DH directs the command to the
appropriate subsystem. All science and engineering data are
collected by the C&DH and then are buffered and formatted for
downlink by the C&DH. The data are downlinked at 1800 bps
immediately and simultaneously dumped into a solid state recorder.
The data stored on the solid state recorder is downlinked 53 minutes
later. These delayed data frames are interleaved into the real-time
data stream, yielding a total downlink rate of 3600 bps. The
purpose of the delayed stream is to receive data acquired during
communications blackout periods and to eliminate the need for a
commandable data recorder.
The LP spacecraft clock or frame counter increments once every 2
seconds. It is stored in a 24-bit register. This means that the
clock will reset after about 33.5 million seconds or about once per
year. The clock reset on January 30, 1999 at about 12:09 UTC, which
was early in the Extended Mission.
Spacecraft Coordinate System
============================
The Trans-Lunar Injection (TLI) stage and spacecraft body
coordinate system is discussed below. The origin of
coordinates is: a) in the separation plane between the
spacecraft and the adapter of the TLI stage; and b) at the
geometric center of the equilateral triangle defined by the
bolt holes for the separation nuts.
The Z axis is normal to the separation plane. The +Z direction
is towards the medium gain antenna (forward) end of the
spacecraft. The X axis is in the separation plane between the
spacecraft and the adapter of the TLI stage. The -X direction
is parallel to the centerline of instrument boom No. 1 and
towards the Gamma Ray Spectrometer. The Y axis is defined by
the right-hand rule.
Instrument Host Overview - DSN
==============================
The Deep Space Network (DSN) is a telecommunications facility
managed by the Jet Propulsion Laboratory of the California Institute
of Technology for the U.S. National Aeronautics and Space
Administration (NASA).
The primary function of the DSN is to provide two-way communications
between the Earth and spacecraft exploring the solar system. To
carry out this function it is equipped with high-power transmitters,
low-noise amplifiers and receivers, and appropriate monitoring and
control systems.
The DSN consists of three complexes situated at approximately
equally spaced longitudinal intervals around the globe at Goldstone
(near Barstow, California), Robledo (near Madrid, Spain), and
Tidbinbilla (near Canberra, Australia). Two of the complexes are
located in the northern hemisphere while the third is in the
southern hemisphere.
Each complex includes several antennas, defined by their diameters,
construction, or operational characteristics: 70-m diameter,
standard 34-m diameter, high-efficiency 34-m diameter (HEF), and
34-m beam waveguide (BWG). These DSN complexes, in conjunction with
telecommunications subsystems onboard planetary spacecraft,
constitute the major elements of instrumentation for radio science
investigations.
For more information see [ASMAR&RENZETTI1993].
Science Packages
================
The Lunar Prospector spacecraft has five science instruments. The
instruments are a Gamma Ray Spectrometer (GRS), a Neutron
Spectrometer (NS), an Alpha Particle Spectrometer (APS), a
Magnetometer (MAG), and an Electron Reflectometer (ER). A Doppler
Gravity Experiment (DGE) uses Doppler tracking data for deriving
gravity measurements. In addition, the spacecraft spin rate and
attitude are determined on the ground from data derived from a sun
sensor and an IR Earth/Moon limb crossing sensor."
END_OBJECT = INSTRUMENT_HOST_INFORMATION
OBJECT = INSTRUMENT_HOST_REFERENCE_INFO
REFERENCE_KEY_ID = "ASMAR&RENZETTI1993"
END_OBJECT = INSTRUMENT_HOST_REFERENCE_INFO
OBJECT = INSTRUMENT_HOST_REFERENCE_INFO
REFERENCE_KEY_ID = "BINDERETAL1998"
END_OBJECT = INSTRUMENT_HOST_REFERENCE_INFO
END_OBJECT = INSTRUMENT_HOST
END
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