CCSD3ZF0000100000001NJPL3IF0PDS200000001 = SFDU_LABEL RECORD_TYPE = STREAM SPACECRAFT_NAME = GALILEO_ORBITER INSTRUMENT_NAME = "NEAR INFRARED MAPPING SPECTROMETER" INSTRUMENT_ID = NIMS OBJECT = TEXT NOTE = "Introduction to this CD-ROM volume." PUBLICATION_DATE = 1998-06-01 END_OBJECT = TEXT END 1. Introduction This is the fifth CD-ROM volume to contain Galileo Near Infrared Mapping Spectrometer (NIMS) Experiment Data Records (EDRs), and the first to contain data from Jupiter operations. It was generated by the NIMS team in collaboration with the Planetary Data System (PDS) and the Multimission Image Processing System (MIPS) for distribution to the various Galileo project investigators, and to the community of planetary scientists. This volume contains all data acquired by the NIMS instrument during Galileo's first four orbits of Jupiter: the Ganymede 1 encounter (G1), the Ganymede 2 encounter (G2), the Callisto 3 encounter (C3) and the Europa 4 encounter (E4), occurring between June and December of 1996. There is also a small amount of calibration data taken before G1, and during the J5 conjunction orbit. Further volumes in this series will contain data from subsequent encounters of Jupiter and its satellites. The Galileo NIMS instrument is an imaging spectrometer which covers the spectral range 0.7 to 5.2 micrometers, measuring both reflected sunlight and emitted thermal radiation in a region not studied by the Pioneer and Voyager spacecraft. Seventeen detectors and a diffraction grating operate to produce spectra over as many as 408 wavelengths. A secondary mirror scans through 20 positions in the cross-cone direction at each grating step to produce a swath of data. The scan platform on which the instrument is mounted is commanded in the cone and clock directions to conduct extensive mapping observations over the target. A complete description of the NIMS instrument and scientific objectives is provided in the article "NEAR-INFRARED MAPPING SPECTROMETER EXPERIMENT ON GALILEO", R. W. Carlson et al., Space Science Reviews v. 60 p. 457-502, 1992. A digital preprint of this article is included in this CD-ROM (see VOLINFO.TXT for its location). NIMS EDRs contain only the raw data collected by the instrument -- in a complex interleaved format. It should be stressed that EDR data require considerable processing before scientific analysis can begin. The desirable form for analysis (the "natural" form for imaging spectrometer data) is the spectral image cube. Such cubes can be generated from EDRs by two separate but similar sets of programs. One operates in the ISIS (Integrated Software for Imaging Spectrometers) environment, the other in the VICAR (Video Image Communication and Retrieval) environment. The resulting cubes are similar in structure but somewhat different in detailed content and type of processing. Both kinds of cubes can be displayed, analyzed and further processed by any ISIS programs that operate on standard ISIS cubes. (See VOLINFO.TXT for more information about the ISIS and VICAR systems.) Systematic processing of the data in the NIMS EDRs -- re-ordering, calibration, pointing correction, map projection, resampling and, where feasible, despiking and removal of systematic noise -- is done by MIPS using the VICAR cube generation software. The resulting cubes are issued on a separate set of CD-ROMs, to which all but experienced users of NIMS data are directed. On the other hand, those who wish to generate their own cubes must start with the EDRs themselves. 2. Summary of Disk Contents This CD-ROM consists principally of NIMS EDR files containing raw data collected from Jupiter and its satellites. Ancillary files provide detailed documentation and assist in the interpretation of the data. Prior to Jupiter operations, EDRs contained up to 100 minutes of NIMS data, and were organized into directory trees ordered in spacecraft clock time. Due to changes in processing necessitated by the failure of Galileo's high gain antenna to deploy, a separate EDR file exists for each NIMS observation during Jupiter operations. EDRs for a number of encounters are grouped on each CD-ROM, where they are organized into target directories. The CD-ROM is organized into a number of root directories. Their contents are summarized below; detailed contents are available in the VOLINFO.TXT file in the DOCUMENT directory, which should be read by any prospective user of the data. Files named *INFO.TXT in each root directory describe its contents. ROOT directory -- basic introductory files: AAREADME.TXT, AAREADME.VMS, ERRATA.TXT, VOLDESC.CAT. CATALOG directory -- mission, instrument and dataset descriptions which are duplicated in the PDS higher-level catalog: MISSION.CAT, INSTHOST.CAT, INST.CAT, DATASET.CAT, REF.CAT. DOCUMENT directory -- basic documentation: VOLINFO.TXT and several brief descriptive files pointed to from the EDR labels. The NIMSINST subdirectory contains a detailed description of the NIMS instrument, a version of the instrument paper. *NIMSGD subdirectories contain detailed "NIMS Guides" to each encounter of Jupiter and its satellites in the period covered by this CD-ROM. INDEX directory -- various index tables for the data files on this CD-ROM: principally EDRCAT.TAB (an index of EDRs) and OBSCAT.TAB (an index of observations). Each table is accompanied by a detached PDS label. LABEL directory -- structure files pointed to by NIMS EDR labels; these are in PDS label format and describe EDR headers and data records: EDRHDR2.FMT, EDRDATA2.FMT. CALIB directory -- NIMS calibration data, or information about where it may be found: tables of NIMS engineering data (including instrument temperatures) no longer contained in EDRs during phase 2, NIMS instrument calibration and dark value files. CALINFO.TXT presently points to a future NIMS CD-ROM which will contain the calibration and dark value files. GEOMETRY directory -- information about SPICE files, which describe spacecraft, planet, scan platform and instrument geometry and timing: GEOMINFO.TXT presently points to a future NIMS CD-ROM which will contain most of these files. Only the I-kernel and boom file are present on this CD. SOFTWARE directory -- information about how to obtain simple software to display NIMS EDR contents: SOFTINFO.TXT. {target directories} -- a root directory for each target for which data is present on this CD-ROM: some or all of JUPITER, IO, EUROPA, GANYMEDE, CALLISTO, MISC (for ring and small satellite data), FLTCAL (for calibration, dark and star data) and CORRUPT (for suspect data). Each target directory has separate subdirectories for EDRs (containing embedded PDS labels), detached VICAR labels and (for some targets) SPIKE files. 3. File formats Most files on this disk have labels encoded in the Object Description Language (ODL) developed by PDS. An ODL label is readable by both humans and computers. It provides a formal description of the format and content of a file. For most files the ODL label appears at the beginning of the file (as is the case for this file). The EDR data and ancillary file formats are described or referenced in the VOLINFO.TXT file in the DOCUMENT directory. PDS label formats and documentation conform to standards as defined by the Planetary Data System Standards Reference (JPL D-7669, Part 2, November 1992, Version 3.0) and the Planetary Science Data Dictionary (JPL D-7116, November 1992, Rev. C) with the following exceptions. Data product labels for the NIMS EDR products were approved prior to the release of the Version 3.0 Standards Reference, so do not strictly conform to the Data Product Label standard in Ch. 5 of the PDS Standards Reference, Version 3.0. In particular, the Standard Formatted Data Unit (SFDU) standard from Chapter 17 of the Planetary Data System Data Preparation Workbook - Volume 2, Standards, May 3, 1991, Version 2.0 is used. 4. Disk Format This disk has been formatted so that a variety of computer systems (e.g. IBM PC, Macintosh, Sun, DEC VAX and DEC Alpha) may access the data. Specifically, the disk is formatted according to the ISO 9660 level 1 Interchange Standard, and file attributes are specified by Extended Attribute Records (XARs). For computer software that fully supports XARs, access to the CD-ROM volume will be straightforward; the disk will appear to the user to be identical to a file system of directories, sub- directories, and data files. Some computer systems that do not support XARs will ignore them; others will append the XAR to the beginning of the file. In the latter case the user must ignore the first 512 bytes of the file. For further information, refer to the ISO 9660 Standard Document: RF# ISO 9660-1988, 15 April 1988. 5. Whom to Contact for Information Information about CD-ROM Hardware and Software and general assistance in CD-ROM use: Data Distribution Laboratory MS 171-264 Jet Propulsion Laboratory 4800 Oak Grove Drive Pasadena, CA 91109 (818) 354-9343 DDL@stargate.jpl.nasa.gov Information about obtaining NIMS CD-ROMs Helen Mortensen Multimission Image Processing System MS 168-514 Jet Propulsion Laboratory 4800 Oak Grove Drive Pasadena, CA 91109 (818) 354-0002 Helen.Mortensen@jpl.nasa.gov Information about contents and structure of NIMS CD-ROMs: Bob Mehlman UCLA/IGPP Los Angeles, CA 90095-1567 (310) 825-2434 rmehlman@igpp.ucla.edu Detailed acknowledgment of contributors to this CD-ROM may be found in Section 12 of the VOLINFO.TXT file in the DOCUMENT directory.