PDS_VERSION_ID = PDS3 RECORD_TYPE = STREAM OBJECT = TEXT PUBLICATION_DATE = 2012-05-14 INTERCHANGE_FORMAT = ASCII NOTE = "N/A" END_OBJECT = TEXT END EARTH-BASED LUNAR RADAR ALTIMETRY MAP 1. Introduction This archive contains digital elevation models (DEMs) of the lunar south pole. SOUTH_POLE_MOSAIC.IMG is a map of a region approximately 1200 x 300 km in area at the lunar south pole. Elevation data at 200 pixels per degree of latitude (~150 m spatial resolution) were obtained with radar interferometry from the Goldstone Solar System Radar in October 1997, as described in MARGOTETAL2000. Delay-Doppler radar images were converted to latitude and longitude using the lunar spin state and prime meridian as specified by the DE405 planetary ephemeris. Elevations are given in meters with respect to a 1737.4 km sphere. Absolute elevations were obtained by comparison with Lunar Reconnaissance Orbiter laser altimetry data (LOLA, NEUMANN2010); a single elevation offset was applied to the radar DEM to minimize (in a least square sense) the differences in elevations with ~300,000 LOLA RDR points throughout the region. We checked for horizontal offsets between the LOLA points, which were produced using the DE421 ephemeris; the two datasets match horizontally to <100 m. No corrections for large-scale slopes in the elevation offsets were applied. Geocoding corrections have not been applied to this data set, so residual errors due to foreshortening remain, with the largest errors (300 m) in areas with elevations farthest from the 1737.4 km reference radius. The median geocoding error is ~100 m. Elevation errors due to noise in the interferometric phase estimates are also of order 100 m. In small, isolated areas (<1% of the map), larger errors due to incorrect phase unwrapping remain. The DEM is formatted as a 8000 x 2000 array in a polar stereographic projection, with the south pole at (x,y) = (4000.5,900.5) (one-based convention). Each cell contains either an elevation measurement or a null value (set to -25000 m). Null values represent areas that were either shadowed from the radar, provided too weak an echo for a reliable elevation measurement, were not simply connected to the rest of the map, or where the data are simply missing. 2. File Formats The data in this archive correspond to NASA Level 2, or PDS Level 5 Derived Data. According to the PDS Standards Reference, these are "derived results, as maps, reports, graphics, etc." Each image file in the archive has an accompanying detached PDS label. Please see dataset.cat for detailed information describing the data. All detached label and document files are stream format files, with a carriage return (ASCII 13) and a line feed character (ASCII 10) at the end of each record. This allows the files to be read by the MacOS, Windows, and Unix operating systems. All tabular files are described by detached PDS labels, which are label files having the same name as the data files they describe, with the extension .LBL. For example, the file INDEX.TAB is accompanied by the detached label file INDEX.LBL in the same directory. Tabular files are formatted so that they may be read directly into many database management systems (DBMS) or spreadsheet programs on various computers. All fields are separated by commas, and character fields are enclosed in double quotation marks ("). The "start byte" and "bytes" values listed in a PDS label do not include the commas between fields or the quotation marks surrounding character fields. The records are of fixed length, and the last two bytes of each record contain the ASCII carriage return and line feed characters. This allows a table to be treated as a fixed length record file on computers that support this file type and as a normal text file on other computers. 3. Archive Contents Files in this archive are organized into a series of subdirectories below the top-level directory. The archive organization and the contents of each directory are described below. Top-level Directory ------------------- AAREADME.TXT The file you are currently reading. VOLDESC.CAT This text file contains a description of the volume contents as a PDS catalog object. It is a required file on PDS archive volumes. ERRATA.TXT This text file contains comments and errata concerning the archive volume. CATALOG Directory ----------------- Files in the CATALOG directory are text files containing documentation formatted in PDS object description language. The files contain information about the facilities and instruments involved in acquiring the data, the data set, references, and personel involved in archiving the data. See the file CATINFO.TXT for details. DATA Directory -------------- The data files and associated PDS labels are stored in the DATA directory. INDEX Directory --------------- The INDEX directory contains a PDS index file for this archive. An index file is an ASCII table with each record (or line) in the table containing information about a single data product in the archive. See the file INDXINFO.TXT for additional details. BROWSE Directory ---------------- The BROWSE directory contains reduced resolution versions of the data products. See BROWINFO.TXT for additional details. 4. Whom to Contact for Information For questions related to the data collection and calibration, contact: Jean-Luc Margot Dept. of Earth and Space Sciences Dept. of Physics and Astronomy University of California, Los Angeles 595 Charles Young Drive East 5642 Geology Building Los Angeles, CA 90095 310-206-8345 E-mail: jlm@ess.ucla.edu or Michael Busch Dept. of Earth And Space Sciences University of California, Los Angeles 595 Charles Young Drive East Los Angeles, CA 90095 310-825-2380 E-mail: mbusch@ess.ucla.edu For questions concerning this volume set, contact: PDS Geosciences Node Washington University 1 Brookings Drive, Campus Box 1169 St. Louis, MO 63130 314-935-9295 Website: http://pds-geosciences.wustl.edu/ E-mail: geosci@wunder.wustl.edu For general information related to the PDS, contact: Planetary Data System, PDS Operator M/S 202-101 Jet Propulsion Laboratory 4800 Oak Grove Drive Pasadena, CA 91109-8099 818-354-4321 Website: http://pds.jpl.nasa.gov/ E-mail: pds_operator@jpl.nasa.gov