Lunar Prospector Reduced Spectrometer Data - Special Products

These Lunar Prospector (LP) gamma ray and neutron spectrometer special products and associated documentation have been prepared by the LP Spectrometer Team as part of a NASA Lunar Data Analysis Program. These spectrometer data products integrate data collected between January 16, 1998 and July 31, 1999. The data file descriptions for these products were provided by:

IMPORTANT: The data on this page are special products that may be of interest to the geoscience community. They do not represent a PDS peer-reviewed archive. Please contact William Feldman or David Lawrence of LANL for more information.  Please report any other anomalies in the data or documentation to geosci@wunder.wustl.edu.

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Introduction

These Lunar Prospector (LP) spectrometer special products contain data from the neutron and gamma ray spectrometers. All data products are provided in two formats: an ASCII table and a binary image.

Each ASCII file contains header information followed by column formatted data separated by commas. Header records begin with a '#' character in the first column. The first four columns of the ASCII version contain the minimum and maximum latitude and longitude values for each pixels. East longitudes are positive. The remaining columns give the parameter value, and, if available, standard deviation values. The ASCII format files are named <name>.txt. File sizes of the ASCII versions vary depending of the bin size.

Each binary file is formatted as an image covering the entire planet with an array of 720 samples and 360 lines. Data values are scaled as integers in the image array with two bytes per pixel in IEEE (MSB first) order. For all binary files except the potassium, radon, and polonium, image values are ten times the values given in the ASCII files. The binary files for potassium abundances have integer values that are the same as values given in the corresponding ASCII file. The binary files for the radon and polonium data have integer values that are 1000 times the values given in the corresponding ASCII file. The binary image is a simple cylindrical map projection with 0.5° pixel size. The first image line corresponds to the south pole and the last image line corresponds to the north pole of the moon. The first sample corresponds to -180° East longitude and the last sample corresponds to 180° East longitude. Binary file names have the form <name>.dat and are about 0.5 MB in size.

Neutron Counting Rate Data Products

Thermal Neutron Counting Rate

The thermal neutron counting rate data product contains data from the LP neutron spectrometer Sn and Cd covered ³He detectors [Feldman et al., 1999, 2001a]. The thermal neutron counting rate is defined as the counting rate difference per 32 seconds between the two detectors and corresponds to neutrons having energies ranging from 0 to 0.4 eV. This data product has been described by Feldman et al. [2000a] and Elphic et al. [2000]. A detailed description of the data reduction for this data product is given by Maurice et al. [2001a]. The map bin size is 60 km by 60 km.

Epithermal Neutron Counting Rate

The epithermal neutron counting rate data product contains data from the LP neutron spectrometer Cd covered ³He detector [Feldman et al., 1999, 2001a]. The epithermal neutron counting rate is defined as the counting rate per 32 seconds from the Cd covered detector and corresponds to neutrons having energies ranging from 0.4 to about 100 eV. The data product has been described by Feldman et al. [2000b, 2001c] and Maurice et al. [2001b]. A detailed description of the data reduction for this data product is given by Maurice et al. [2001a]. The map bin size is 60 km by 60 km.

Fast Neutron Counting Rate

The fast neutron counting rate data product contains data from the LP gamma ray spectrometer [Feldman et al., 1999, 2001b]. The fast neutron counting rate is defined as the counting rate per 32 seconds of fast neutrons having energies from 0.6 to about 9 MeV. The data product has been described by Maurice et al. [2000]. A detailed description of the data reduction for this data product is given by Maurice et al. [2001a]. The map bin size is 60 km by 60 km.

Fast Neutron Spectra Counting Rate

The fast neutron spectra counting rate data product contains data from the LP gamma ray spectrometer [Feldman et al., 1999, 2001b]. The fast neutron spectra counting rate is defined as the counting rate per 32 seconds of fast neutrons having energies from 0.6 to about 9 MeV. These energies are then divided into 16 channels having midpoint energies of 0.743, 1.40, 2.09, 2.67, 3.24, 3.75, 4.23, 4.70, 5.18, 5.65, 6.11, 6.55, 6.98, 7.41, 7.82, and 8.24 MeV. This data product has been described by Maurice et al. [2000]. A detailed description of the data reduction for this data product is given by Maurice et al. [2001a]. Furthermore, a description of how the counting rates can be converted into fluxes is given by Maurice et al. [2000] and Byrd and Urban [1994]. The map bin size is 60 km by 60 km. For the binary image file, the channels are stored in band sequential order.

5 Degree Elemental Abundance Data Products

Elemental abundance values for O, Si, Ti, Al, Fe, Mg, Ca, U, and K were derived from LP gamma ray spectrometer [Feldman et al., 1999] observations acquired during the high-altitude portion of the LP mission. For the elements O, Si, Ti, Al, Fe, Mg, and Ca, the data are given in units of elemental weight percent. For the elements U and K, the data are given in units of ppm. A description of the reduction of these data products is given by Prettyman et al. [2002]. The Thorium data has been calculated using full modeling and response function analysis [Prettyman et al., 2002]. The map bin size is 150 km by 150 km.

2 Degree Elemental Abundance Data Products

Samarium Abundance Data Product

The samarium abundance data product contains data from the LP neutron and gamma ray spectrometers [Feldman et al. 1999, 2001a] taken during the low-altitude portion of the LP mission. This data product is given in units of microgram/gram. A detailed description of the data reduction of this data type is given by Elphic et al. [2000]. The map bin size is 60 km x 60 km.

Titanium and Potassium Abundance Data Products

These data products contain elemental abundances values for Ti and K derived from LP gamma ray spectrometer [Feldman et al., 1999] observations acquired during the high- and low-altitude portions of the LP mission. For Ti, the data are given in units of elemental weight percent. For K, the data are given in units of ppm. A description of the reduction of these data products is given by Prettyman et al. [2002]. The map bin size is 60 km by 60 km.

Hydrogen Abundance Data

The hydrogen abundance data product contains data from the LP neutron spectrometer [Feldman et al., 1999, 2001a] acquired during the low-altitude portion of the LP mission. Hydrogen abundances are derived from epithermal neutron data that has been corrected by thermal neutron data [Feldman et al., 2001c]. Equations 3 and 4 of Feldman et al. [2001c] show how the corrected epithermal data is converted into hydrogen abundances as parts per million (ppm). Note, however, that these abundances are not necessarily reliable in regions of high thorium and rare-earth element abundances [Maurice et al., 2001a]. The map bin size is 60 km x 60 km.

Thorium Abundance Data

The 2 degree thorium abundance data products contains data from the LP gamma ray spectrometer [Feldman et al., 1999, 2001b]. These absolute abundances are given in units of microgram/gram. There are two versions containing data taken from the high- and low-altitude portions of the LP mission [Lawrence et al., 2000]. These data have been described by Lawrence et al. [2000]. A detailed description of the data reduction for these data is given by Lawrence et al. [2001b]. The map bin size is 60 km x 60 km.

Half Degree Abundance Data Products

Thorium Abundance Data

The half degree thorium abundance data product contains data from the LP gamma ray spectrometer [Feldman et al., 1999]. The absolute abundances are given in units of ppm. These data are taken from the low-altitude portion of the LP mission. A description of the reduction of these data products is given by Lawrence et al. [2002a, 2002b]. The map bin size is 0.5° by 0.5°.

Iron Abundance Data

The half degree iron abundance data product contains data from the LP gamma ray spectrometer [Feldman et al., 1999] acquired during the low-altitude portion of the LP mission. The absolute abundances are given in units of FeO weight percent. A description of the reduction of these data products is given by Lawrence et al. [2002a, 2002b]. The map bin size is 0.5° by 0.5°.

Hydrogen Abundance Data

The half degree hydrogen abundance data product contains data from the LP neutron spectrometer [Feldman et al., 1999]. Hydrogen abundances are derived from epithermal neutron data that has been corrected by thermal neutron data [Feldman et al., 2001c]. Equations 3 and 4 of Feldman et al. [2001c] show how the corrected epithermal data is converted into hydrogen abundances as parts per million (ppm). Note, however, that these abundances are not necessarily reliable in regions of high thorium and rare-earth element abundances [Maurice et al., 2001a]. The map bin size is 0.5° by 0.5°.

Radon-222 and Polonium-210 Relative Count Rate Data Products

Relative count rate data products for radon-222 and polonium-210 contain data from the LP alpha particle spectrometer acquired during the high- and low-altitude portions of the LP mission. These data are given in units of counts per second. A description of the reduction of these data products is given by Lawson et al. [2002]. The data are mapped onto equal-area pixels having an approximate size at the equator of 300 km in the longitude direction and 450 km in the latitude direction.

Data Product Summary

References

(Contact David Lawrence of Los Alamos National Laboratory for information on references that are in preparation or in press).

Byrd, R. C., and W. T. Urban, Calculation of the neutron response of Boron-loaded scintillators, LAUR-12833-MS, Los Alamos, National Laboratory, Los Alamos, NM, 1994.

Elphic, R. C., D. J. Lawrence, W. C. Feldman, B. L. Barraclough, S. Maurice, A. B. Binder, and P. G. Lucey, Determination of lunar global rare earth element abundances using Lunar Prospector neutron spectrometer observations, J. Geophys. Res., 105, 20,333-20,346, 2000.

Feldman W. C., B. L. Barraclough, K. R. Fuller, D. J. Lawrence, S. Maurice, M. C. Miller, T. H. Prettyman, and A. B. Binder, the Lunar Prospector Gamma-Ray and Neutron Spectrometers, Nuclear Instruments and Methods in Physics Research A, 422, 562-566, 1999.

Feldman, W. C., D. J. Lawrence, R. C. Elphic, D. T. Vaniman, D. R. Thomsen, B. L. Barraclough, S. Maurice, and A. B. Binder, The chemical information content of lunar thermal and epithermal neutrons, J. Geophys. Res., 105, 20,347-20,363, 2000a.

Feldman, W. C., D. J. Lawrence, R. C. Elphic, B. L. Barraclough, S. Maurice, I. Genetay, and A. B. Binder, Polar hydrogen deposits on the Moon, J. Geophys. Res., 105, 4175-4195, 2000b.

Feldman, W. C., et al., Instrument description of the Lunar Prospector Neutron Spectrometer, in preparation, 2001a.

Feldman, W. C., et al., Instrument description of the Lunar Prospector Gamma-ray Spectrometer, in preparation, 2001b.

Feldman, W. C., S. Maurice, D. J. Lawrence, R. C. Little, S. L. Lawson, O. Gasnault, R. C. Wiens, B. L. Barraclough, R. C. Elphic, T. H. Prettyman, J. T. Steinberg, and A. B. Binder, Evidence for water ice near lunar poles, J. Geophys. Res., in press, 2001c.

Lawrence, D. J., W. C. Feldman, B. L. Barraclough, R. C. Elphic, T. H. Prettyman, S. Maurice, A. B. Binder, and M. C. Miller, Thorium abundances on the lunar surface, J. Geophys. Res., 105, 20,307-20,331, 2000.

Lawrence, D. J., W. C. Feldman, R. C. Elphic, S. Maurice, T. H. Prettyman, and A.  B. Binder, Iron abundances on the lunar surface as measured by the Lunar Prospector Gamma-Ray Spectrometer, 32nd Lunar and Planetary Science Conference, Abstract #1830, 2001a.

Lawrence D. J., et al., Data reduction procedures for the Lunar Prospector Gamma-ray Spectrometer, in preparation, 2001b.

Lawrence, D. J., W. C. Feldman, R. C. Elphic, R. C. Little, T. H. Prettyman, S. Maurice, P. G. Lucey, and A. B. Binder, Iron abundances on the lunar surface as measured by the Lunar Prospector Gamma-Ray and Neutron Spectrometers, J. Geophys. Res., submitted, 2001c.

Lawrence, D. J., R. C. Elphic, W. C. Feldman, O. Gasnault, I. Genetay, S. Maurice, and T. H. Prettyman, Optimizing the spatial resolution for gamma-ray measurements of thorium abundances on the lunar surface, New Views of the Moon, Europe, 12-14 Jan., 2002a.

Lawrence, D. J., R. C. Elphic, W. C. Feldman, O. Gasnault, I. Genetay, S. Maurice, and T. H. Prettyman, Small-area thorium enhancements on the lunar surface, 33rd Lunar and Planetary Science Conference, Abstract #1970, 2002b

Lawson, S. L., W. C. Feldman, D. J. Lawrence, K. R. Moore, S. Maurice, R. D. Belian, and A. B. Binder, Maps of lunar radon-222 and polonium-210, 33rd Lunar and Planetary Science Conference, Abstract #1835, 2002.

Maurice, S., W. C. Feldman, D. J. Lawrence, O. Gasnault, C. d'Uston, and P. G. Lucey, High-energy neutrons from the Moon, J. Geophys. Res., 105, 20,365-20,375, 2000.

Maurice, S., et al., Data reduction procedures for the Lunar Prospector Neutron Spectrometer, in preparation, 2001a.

Maurice, S., R. C. Elphic, W. C. Feldman, R. Little, D. J. Lawrence, I. Genetay, C. d'Uston, O. Gasnault, S. Chevrel, and A. B. Binder, Rare-earth elements on the Moon from epithermal neutrons, J. Geophys. Res., submitted, 2001b.

Prettyman, T. H., W. C. Feldman, D. J. Lawrence, G. W. McKinney, A. B. Binder, R. C. Elphic, O. M. Gasnault, S. Maurice, and K. R. Moore, Library least squares analysis of Lunar Prospector gamma-ray spectra, 33rd Lunar and Planetary Science Conference, Abstract #2012, 2002.