PDS_VERSION_ID = PDS3 RECORD_TYPE = STREAM OBJECT = TEXT PUBLICATION_DATE = 2011-10-21 INTERCHANGE_FORMAT = ASCII NOTE = "N/A" END_OBJECT = TEXT END Chandrayaan-1 Lunar Orbiter Spacecraft (Ch-1) Moon Mineralogy Mapper (M3) Data Archive 1. Introduction This archive contains data acquired by the Chandrayaan-1 Lunar Orbiter Spacecraft (Ch-1) Moon Mineralogy Mapper (M3) instrument. Specifically, this archive includes version 3 of the L1B data products as acquired during the time period of November 2008 through August 2009. As of Septemer 2011, we have developed a detector-temperature-driven empirical gain adjustment to the M3 Level 1B data. We refer to this correction as the SSC_ADJ correction and it is based on a family of spectral gain curves that are applied to each Level 1B radiance cube after its nominal radiometric calibration. Based on the detector temperature for each scene, a single curve is chosen from the family of temperature-based curves and each spectrum in the radiance cube is multiplied by this correction factor. This update should replace versions 1.0 and 2.0 of the M3 Level 1B data products. 2. File Formats This section describes the format of M3 Archive Volumes. Data that comprise the Archive will be formatted in accordance with Planetary Data System standards. 2.1. Disk Format Archive Volumes are formatted so that when 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 Formats Document files with the .TXT suffix exist in the ROOT, DATA, INDEX, CATALOG, DOCUMENT, LABEL, CALIB, GEOMETRY and EXTRAS directories. They are ASCII files which may have embedded PDS labels. Lines in a .TXT file end 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. Some documents in the DOCUMENT contain formatting and figures that cannot easily be rendered as ASCII text. Therefore each document is given in PDF 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. Some type of ASCII text versions of these documents will also be included, possibly using HTML or XML, in order to meet the PDS requirement that documents must be archived as ASCII text. 2.2.2. Tabular File Format Tabular files (.TAB suffix) exist in the INDEX and CALIB directory. Tabular files are ASCII files formatted for direct reading into many database management systems on various computers. Every M3 tabular file is described by a detached PDS label with the same name as the data file it describes, and the extension .LBL. For example, the file INDEX.TAB is accompanied by the detached label file INDEX.LBL in the same directory. 2.2.2.1 INDEX Directory All fields for tabular files in the INDEX directory are separated by commas. (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" listed in the labels indicate the starting position in bytes of each field in a record; the field length "bytes" does not include the commas between 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 text file with embedded line delimiters on those that do not. 2.2.2.2 CALIB Directory All fields for tabular files in the CALIB directory are separated by spaces. Numberic fields are right justified. The "start byte" listed in the labels indicate the starting position in bytes of each field in a record. The records are of fixed length, and the last two bytes of each record contain the ASCII carriage return and line feed characters. 2.2.3. PDS Label Format All data files in the M3 archive have PDS labels detached in a separate file. For examples of PDS labels for each type of data product, see the Data Product SIS in the DOCUMENT directory. A PDS label provides descriptive information about the associated file. The PDS label is an object-oriented structure consisting of sets of 'keyword=value' declarations. The object to which the label refers (e.g. IMAGE, TABLE, etc.) is denoted by a statement of the form: ^object = location in which the carat character (^, also called a pointer in this context) indicates where to find the object. In an embedded label, the location is an integer representing the starting record number of the object (the first record in the file is record 1). In a detached label, the location denotes the name of the file containing the object, along with the starting record or byte number, if there is more than one object in the file. For example: ^HEADER = ("F01.IMG",1) ^IMAGE = ("F01.IMG",1025 ) indicates that the IMAGE object begins at byte 1025 of the file F01.IMG, in the same directory as the detached label file.Below is a list of the possible formats for the ^object definition. ^object = n ^object = n ^object = "filename.ext" ^object = ("filename.ext",n) ^object = ("filename.ext",n) where n is the starting record or byte number of the object, counting from the beginning of the file (record 1, byte 1), indicates that the number given is in units of bytes, filename is the up to 28 character, alphanumeric upper-case file name, ext is the 3 character upper-case file extension Lines of text in detached labels end 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. Note that the RECORD_TYPE keyword located in the first five lines of the PDS label has the value UNDEFINED because the label points to multiple data types. 2.2.4. Catalog File Format Catalog files (suffix .CAT) exist in the ROOT and CATALOG directories. They are text files formatted in an object-oriented structure consisting of sets of 'keyword=value' declarations, so that they are readable by humans and by software. 2.2.5 Science Data File Formats For more information about the format and content of the data products, see the discussions in the M3 Data Product and Archive Volume SISs located in the DOCUMENT directory. Please note that unlike the M3 Level 1B data products, which are viewable with NASAView, the M3 Level 0 data products are not compatible with NASAView. However, ENVI software can view both Level 0 and Level 1B data products. Reading M3 Level 0 Data Products with other standard viewing tools may not be possible due to the non-standard float format of the 1280-byte line prefix header, included in all M3 Level 0 Data Products. The Indian Space Research Organisation (ISRO), creator of the data, uses a non-PDS standard for capturing and organizing these values within the header. This format is not describable using existing PDS3 data types. Given that the M3 mission was of an international nature, the M3 team along with the PDS, had no authority to obligate ISRO to conform to the American PDS standards. Therefore, for the sake of our current PDS data users and those in the future, we have documented a description of the L0 data prefix header structure in various places within this archive. This includes the M3_L0_TIME_DECODING.TXT file within the DOCUMENT sub-directory, the LN_PRFX_HDR.FMT file within the LABEL sub-directory and the ERRATA.TXT file within the top level volume directory. 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 a listing of comments and updates 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 DATA directory contains version 1.0 of M3 Level 0 (EDR) and version 3.0 of Level 1B (RDR) data products. See dpsis.pdf for details. INDEX Directory --------------- The INDEX directory contains PDS index files 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. Files in the Index directory are provided to help the user locate products on the archive volume. See the file INDXINFO.TXT for additional details. DOCUMENT Directory ------------------ The DOCUMENT directory contains contains documentation to help the user understand and use the archive data. See DOCINFO.TXT for a description of the files in the DOCUMENT directory. CATALOG Directory ----------------- The files in the Catalog directory provide a top-level understanding of the mission, spacecraft, instruments, and data set. The files in this directory become part of the PDS Catalog to provide background information for the user searching for data. Their format and contents are further specified in the PDS Standards Reference. See the file CATINFO.TXT for details. GEOMETRY Directory ----------------- The Geometry directory contains a single file, GEOMINFO.TXT, which directs the reader to the various SPICE kernels that contain the data necessary to interpret observation geometry. CALIB Directory ------------------ The CALIB directory contains various reports documenting different aspects of instrument behavior. See CALINFO.TXT for a description of the files in the CALIB directory. EXTRAS Directory --------------- The EXTRAS directory contains other materials that the user may find helpful, but that are beyond the scope of the required elements of the archive. 4. Whom to Contact for Information For questions concerning this volume set, contact: PDS Imaging Node Jet Propulsion Laboratory 4800 Oak Grove Dr. Pasadena, CA 91109 (818) 354-5677 WWW Site: http://pds-imaging.jpl.nasa.gov E-mail: Susan.K.LaVoie@jpl.nasa.gov 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 For questions concerning the generation of M3 products, contact: Sarah R. Lundeen M/S 171-B1 Jet Propulsion Laboratory 4800 Oak Grove Dr. Pasadena, CA 91109 (818) 354-8557 E-mail: sarah.r.lundeen@jpl.nasa.gov