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LP MOON SPACECRAFT ATTITUDE V1.0 (PDS)

NSSDCA ID: PSPG-00779

Availability: Archived at NSSDC, accessible from elsewhere

Description

This description was generated automatically using input from the Planetary Data System.

Data Set Overview ================= The Lunar Prospector attitude data set consists of values for the spacecraft spin rate and spin axis orientation (attitude) as a function of time. These values are determined from spacecraft attitude data (sun and limb crossing sensors) and ephemeris data. The details as to how attitude and spin rate are determined are given in the Project's Ground Software User's Guide and Programmer's Guide [JACOBSEN1998]. Spacecraft orientations are given as right ascension and declination of the spacecraft spin axis in the Mean-of-J2000 Ecliptic reference frame. The attitude data set consists of a single, cumulative file for the entire mission. Records are added to this file following each significant change in either the spin rate or spin axis orientation. The spacecraft spin rates and attitudes in this data set are orbit averages. The instantaneous spin rate can be determined from the sun pulse data set. The instantaneous spin rate varies as the spacecraft passes into and out of the Moon's shadow and after each spacecraft maneuver. Generally, an attitude record is included for times immediately before and after each maneuver. Science Objectives ================== The Lunar Prospector science objectives relevant to this data set are to map the Moon's surface composition and its magnetic field, and to determine the frequency and location of gas release events. A special emphasis of the science objectives is to search for polar water ice deposits [BINDERETAL1998]. The spacecraft attitude and spin rate data are used to determine the spacecraft orientation at the time science data were acquired. Data Set Overview ================= The sun pulse data set is a record of times that the Lunar Prospector sun sensor detects the Sun. These sun pulse times are derived from ground processing of the sun sensor data, earth-moon limb sensor data, and the spacecraft ephemeris. This data set is part of the Lunar Prospector Level 0 data archive. The sun pulse times are used in determining the spacecraft spin rate and orientation as a function of time. Because the Lunar Prospector spacecraft is sometimes in eclipse with the Sun, the sun pulse data set is generated on the ground to include both actual sun pulse times based on the sun sensor measurements and estimated sun pulse times based on the history of spin rate change during all prior eclipses. See the CONFIDENCE_LEVEL_NOTE field for further information on how sun pulse time is estimated during eclipses. The sun pulse data set is organized into files, each of which cover about 4-6 hours of time. In general, each sun pulse file matches the time range of a corresponding merged telemetry file. There is usually one sun pulse record for every other minor frame of the merged telemetry file. Science Objectives ================== The Lunar Prospector science objectives relevant to this data set are to map the Moon's surface composition and its magnetic field, and to determine the frequency and location of gas release events. A special emphasis of the science objectives is to search for polar water ice deposits [BINDERETAL1998]. Data Set Overview ================= The command file data set contains a record of all commands sent to the Lunar Prospector spacecraft. The command files document any changes in spacecraft and science instrument operating modes or other settings. The files are ASCII text records of the commands and associated parameters. A complete list of spacecraft commands can be found in Appendix B of the Level 0 Data Product SIS, which is included in the Lunar Prospector Level 0 Data archive. Each file in the command data set contain uplink commands for a given commanding session. Such uplink sessions can occur every few days. Science Objectives ================== The Lunar Prospector science objectives relevant to this data set are to map the Moon's surface composition and its magnetic field, and to determine the frequency and location of gas release events. A special emphasis of the science objectives is to search for polar water ice deposits [BINDERETAL1998]. Data Set Overview ================= The Lunar Prospector ephemeris data set consists of spacecraft position and velocity determinations as a function of time in Moon-centered, Earth equator, mean of J2000 coordinates. Tracking data collected by ground stations are used by the Goddard Flight Dynamics Analysis Branch (FDAB) to compute the Lunar Prospector orbit ephemeris. The Level 0 Data archive contains the ephemeris type known as the 'definitive ephemeris', which is based on an updated lunar gravity model [FDAB1997]. Each file in the ephemeris data set covers approximately 24 hours. Science Objectives ================== The Lunar Prospector science objectives relevant to this data set are to map the Moon's surface composition and its magnetic field, and to determine the frequency and location of gas release events. A special emphasis of the science objectives is to search for polar water ice deposits [BINDERETAL1998]. The spacecraft ephemeris data are used to locate where on the Moon science data were acquired. Data Set Overview ================= The Lunar Prospector spacecraft position data set consists of spacecraft position in selenographic latitude, longitude, and altitude coordinates in one minute intervals. The data set also contains spacecraft velocity and distance from the center of the Moon as a function of time. The coordinate system is selenographic with east longitude positive. The data set is generated by the Goddard Flight Dynamics Analysis Branch. Each file in the spacecraft position data set covers 24 hours of time. Science Objectives ================== The Lunar Prospector science objectives relevant to this data set are to map the Moon's surface composition and its magnetic field, and to determine the frequency and location of gas release events. A special emphasis of the science objectives is to search for polar water ice deposits [BINDERETAL1998]. The spacecraft position data are used to locate where on the Moon science data were acquired. Data Set Overview ================= The Lunar Prospector merged telemetry data set is a result of comparing the two Lunar Prospector telemetry data streams and selecting one of them. The Lunar Prospector raw telemetry data downlink stream contains data transmitted in real-time and data that was collected about 50 minutes prior and stored on the spacecraft. The purpose of the delayed stream is to capture data acquired during communications blackouts. See the CONFIDENCE_LEVEL_NOTE field for a description of the merging process. The merged telemetry data set contains raw science and instrument engineering data acquired by all of the science instruments (Gamma Ray, Neutron, and Alpha Particle Spectrometers, and the Magnetometer and Electron Reflectometer), along with spacecraft engineering data. As such, the merged telemetry files are part of the Lunar Prospector Level 0 data archive. The data set is organized into binary files with each file containing about 4-6 hours of data. Each record in a given file is a main (minor) frame containing 2 seconds of downlinked data. A major frame consists of 16 minor frames. Science Objectives ================== The Lunar Prospector science objectives relevant to this data set are to map the Moon's surface composition and its magnetic field, and to determine the frequency and location of gas release events. A special emphasis of the science objectives is to search for polar water ice deposits [BINDERETAL1998]. These data are available on-line from the Planetary Data System (PDS) at: http://pds-geosciences.wustl.edu/LUNAR01/prospectorcd/lp_0001/

Alternate Names

  • LP MOON MERGED TELEMETRY DATA V1.0 (PDS)
  • LP MOON SPACECRAFT EPHEMERIS V1.0 (PDS)
  • LP MOON SPACECRAFT POSITION V1.0 (PDS)
  • LP MOON SUN PULSE DATA V1.0 (PDS)
  • LP MOON UPLINK COMMAND V1.0 (PDS)
  • LP-L-6-EPHEMERIS-V1.0
  • LP-L-6-POSITION-V1.0
  • LP-L-ENG-6-ATTITUDE-V1.0
  • LP-L-ENG-6-COMMAND-V1.0
  • LP-L-ENG-6-SUNPULSE-V1.0
  • LP-L-ENG/GRS/NS/APS/MAG/ER-1-MDR-V1.0

Discipline

  • Planetary Science: Geology and Geophysics

Additional Information

Spacecraft

Experiments

Questions and comments about this data collection can be directed to: Dr. David R. Williams

 

Personnel

NameRoleOriginal AffiliationE-mail
Dr. William C. FeldmanData ProviderLos Alamos National Laboratorywfeldman@lanl.gov
Dr. Alan B. BinderGeneral ContactLockheedabinder@mail.arc.nasa.gov
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