PDS_VERSION_ID = PDS3 RECORD_TYPE = STREAM OBJECT = TEXT PUBLICATION_DATE = 2007-08-02 INTERCHANGE_FORMAT = ASCII NOTE = "N/A" END_OBJECT = TEXT END Mars Reconnaissance Orbiter (MRO) Shallow Radar (SHARAD) Data Archive 1. Introduction This archive contains data acquired by the Mars Reconnaissance Orbiter (MRO) Shallow Radar (SHARAD) instrument. 2. File Formats This section describes the format of SHARAD Archive Volumes. Data that comprise the Archive will be formatted in accordance with Planetary Data System standards. 2.1. Volume Format The SHARAD archives will be maintained online for electronic access, with backup copies stored offline. The online archives will be formatted as a single EDR volume and a single RDR volume to which data directories are added with each delivery during the MRO mission. It is possible that all or part of the SHARAD archive may need to be written to physical media, e.g. CD or DVD, for delivery if electronic delivery is not desirable. Archive Volumes are formatted so that if written to CD or DVD media according to PDS policy, the media are compatible with most commonly used computer operating systems including Windows, Unix, and Macintosh systems. The CD volume format is in accordance with ISO 9660 level 2 Interchange Standard. The DVD volume format is in accordance with the UDF Standard with ISO 9660 Level 2 compatibility. 2.2. File Formats This section describes file formats for the kinds of files contained on Archive Volumes. 2.2.1. Document File Format Document files with the .TXT suffix are ASCII files which may have embedded PDS labels. Each line in a .TXT file ends with a carriage return character (ASCII 13) and a line feed character (ASCII 10). This allows the files to be readable under various operating systems. Documents in the Document directory may contain formatting and figures that cannot be rendered as ASCII text. Therefore each document is given in two formats, hypertext and PDF. The hypertext file contains ASCII text plus hypertext markup language (HTML) commands that enable it to be viewed in a Web browser such as Netscape Navigator or Microsoft Internet Explorer. The hypertext file may be accompanied by ancillary files such as images and style sheets that are incorporated into the document by the Web browser. The second format, PDF (Portable Document Format) is a proprietary format of Adobe Systems Incorporated that is frequently used for distributing documents. Adobe offers free software, Acrobat Reader, for viewing PDF files. 2.2.2. Tabular File Format Tabular files (.TAB suffix) are ASCII files formatted for direct reading into many database management systems or spreadsheet programs on various computers. All fields are separated by commas, and character fields are enclosed in double quotation marks ("). (Character fields are padded with spaces to keep quotation marks in the same columns of successive records.) Character fields are left justified, and numeric fields are right justified. The "start byte" and "bytes" values listed in the labels 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. All tabular files are described by PDS labels, either embedded at the beginning of the file or detached. If detached, the PDS label file has the same name as the data file it describes, with the extension .LBL; for example, the file INDEX.TAB is accompanied by the detached label file INDEX.LBL in the same directory. 2.2.3. PDS Label Format All data files in the archive have detached PDS labels. PDS labels are ASCII text files intended to be read by humans and by software. A PDS label consists of a series of statements in the form "keyword = value", where keywords are defined in either the main PDS Data Dictionary or the MRO Local Data Dictionary. For examples of PDS labels for SHARAD products, see the Data Product SIS Documents. Each line of text in a detached label ends with a carriage return character (ASCII 13) and a line feed character (ASCII 10). This allows the files to be readable under various operating systems. 2.2.4. Catalog File Format Catalog files (suffix .CAT) exist in the Root and Catalog directories. They are ASCII text files formatted in an object-oriented structure consisting of sets of 'keyword=value' declarations. Each line of text in a catalog file ends with a carriage return character (ASCII 13) and a line feed character (ASCII 10). This allows the files to be readable under various operating systems. 2.2.5. Science Data File Formats A SHARAD EDR data product consists of a pair of binary tables described by a single detached PDS label. The Science Telemetry table is an aggregation of data blocks, where one row in the table contains one block. A data block is a single observation of the SHARAD instrument, a sequence of echoes along with some header information. The Auxiliary Data table has one row for each row in the Science Telemetry table. The auxiliary data in this table include geometry information, housekeeping data, and quality flags. A single SHARAD EDR Data Product includes all data blocks belonging to a single data take, i.e., all data that have been acquired continuously in time using the same instrument settings. A data take corresponds to a single entry in the SHARAD Operation Sequence Table. Data takes can vary in duration from a few seconds to thirty minutes or more. Thus the content of each SHARAD data product is highly variable in terms of number of data blocks, and depends on how operations for the instrument were planned during a given data collection period. Each SHARAD RDR product contains SHARAD Experiment Data Record (EDR) data that have been Doppler filtered, range compressed and converted to complex voltages, and possesses proper engineering and spacecraft information. Each Data Product will consist of two files: one is a binary file containing the scientific data of the instrument, that is a sequence of processed echoes, each of which is preceded by a header containing information on the collection and on-board processing of the data, and followed by parameters characterizing the ground processing of the echoes, by geometric quantities generated on-ground from spacecraft navigation data, and by parameters extracted from instrument and spacecraft housekeeping telemetry. The second file is a detached ASCII label describing the content of the data product. For more information about the format and content of the data products, see the EDR Data Product SIS and the RDR Data Product SIS, which can be found in the "document" directory. 2.2.6 Browse File Formats Browse versions of SHARAD RDR products are provided in the form of JPEG images. Each browse file is accompanied by a detached PDS label that describes how the image was created. 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. ERRATA.TXT This text file contains comments and errata concerning the archive volume. 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. DATA Directory -------------- The experiment data records for SHARAD 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 archive. See the file INDXINFO.TXT for additional details. DOCUMENT Directory ------------------ The DOCUMENT directory contains document files relating to this archive. See DOCINFO.TXT for a description of the files in the DOCUMENT directory. CATALOG Directory ----------------- Files in the CATALOG directory are text files containing documentation formatted in PDS object description language. The files contain information about the MRO mission and spacecraft, the SHARAD instrument, the data set, the personnel involved in creating the data archive, and references. See the file CATINFO.TXT for details. CALIB Directory ------------------ The CALIB directory contains calibration files used to process the data products. See CALINFO.TXT for a description of the files in the CALIB directory. LABEL Directory ------------------ The LABEL directory contains files that describe data format and organization. See LABINFO.TXT for a description of the files in the LABEL directory. BROWSE Directory ------------------- The BROWSE directory contains JPEG images of SHARAD RDR products, organized in the same subdirectory structure as the DATA directory. See BROWINFO.TXT for a description of files in the BROWSE directory. 4. Whom to Contact for Information 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 Web Site: 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 WWW Site: http://pds.jpl.nasa.gov/ E-mail: pds_operator@jpl.nasa.gov 5. Cognizant Persons This archive volume designed and produced at the PDS Geosciences Node, Washington University, St. Louis, Missouri by Susan Slavney and Jennifer Ward.