Data Set Information
DATA_SET_NAME NIMS EXPERIMENT DATA RECORDS: GASPRA/IDA ENCOUNTERS
DATA_SET_ID GO-A-NIMS-2-EDR-V1.0
NSSDC_DATA_SET_ID 89-084B-01C
DATA_SET_TERSE_DESCRIPTION Galileo Imaging Spectrometer (NIMS) Asteroids Gaspra and Ida Experiment Data Records
DATA_SET_DESCRIPTION
Data Set Overview
  =================
    NIMS Experiment Data Record (EDR) files contain raw data from
    the Galileo Orbiter Near-Infrared Mapping Spectrometer
    (CARLSONETAL1992).  This raw data requires considerable
    processing before it is readily amenable to science analysis.
    The EDRs comprise the base dataset from which spectral image
    cubes will be created by continually evolving software using
    successively more accurate calibration and geometry data.
 
 
  Parameters
  ==========
    The files consist principally of 10-bit sensor values from the
    17 NIMS detectors ordered by time of acquisition, but these are
    interleaved with NIMS background and housekeeping values, and,
    less frequently, various instrument temperatures, AACS (scan
    platform and rotor pointing) data and engineering measurements.
    Sensor values are measured simultaneously in all detectors; a
    set of 17 values is acquired at each of 20 cross-track
    positions (via a secondary scanning mirror) in a period of 1/3
    second.  A grating may step between mirror scans; as many as 24
    steps may result in 20 spectra of as many as 408 wavelengths
    each.  A second spatial dimension is added by spacecraft and
    scan platform motion.
 
 
  Processing
  ==========
    The EDRs are generated by the Multimission Image Processing
    System (MIPS) at the Jet Propulsion Laboratory (JPL) from data
    sources derived ultimately from decommutated Galileo telemetry.
    They are divided into files containing up to 100 RIMs (60 2/3
    second intervals) of data.  Each file contains the best data
    available from the several ground stations receiving Galileo
    telemetry.
 
 
  Data
  ====
    The data are organized into 1024-byte records, one for each
    minor frame (2/3 second) of spacecraft clock time.  In that
    time, the NIMS instrument has collected sensor values for all
    17 detectors over two scans (20 positions down and 20 positions
    up) of the secondary mirror.
 
    A detailed description of the structure of the EDR may be found
    in the Galileo Software Interface Specification (ZAMANI1991).
    The same information is available in both human and
    machine-readable form in the Planetary Data System (PDS)
    structure files on the NIMS EDR CD-ROM volumes.
 
    As received from MIPS, each file has a Vicar label preceding a
    PDS/ISIS label.  The Vicar labels have been removed from the
    EDRs on the CD-ROMs but they are present in detached form.  The
    PDS/ISIS-labelled EDRs themselves may be readily displayed and
    further processed by software in the ISIS system, and by PDS
    utilities.
 
 
  NOTE
  ====
    The failure of the Galileo high gain antenna will result in
    extensive modifications to NIMS operations and data structures
    during Jupiter operations.  Extensive editing and compression
    of NIMS data will occur on the spacecraft, and the EDR
    structure will necessarily be different during phase 2.
 
 
  Ancillary Data
  ==============
    A Postscript-format Guide to the planned observations,
    including footprint plots on the target, instrument parameters,
    etc.  is included with the EDRs on the CD-ROM, as are tables of
    parameters for each EDR file, each observation and each RIM of
    data, files of observed dark values in different modes and gain
    states, a digitized map of the Galileo booms in cone-clock
    space and tables of NIMS internal geometry and timing.
 
    Calibration files, spike files and SPICE files (spacecraft
    positions, planetary positions and constants, processed
    pointing geometry, spacecraft clock versus universal time,
    etc.) may be included in later volumes of the CD-ROM set.
    Presently, calibration files are packaged with cube generation
    software in the ISIS and Vicar systems, and SPICE files may be
    obtained from the Galileo Science Data Team.
 
 
  Software
  ========
    Simple software is available on the EDR CD-ROMs for displaying
    the raw data in various ways, but use of this software requires
    considerable familiarity with the operation of the NIMS
    instrument.  Most science analysis requires generation of
    spectral image cubes using ancillary geometric data, and
    decalibration of the raw data numbers.  This may be done with
    one of several similar sets of cube generation programs
    available in the ISIS and Vicar systems.  (Data cubes generated
    in this way will be made available in a separate series of
    CD-ROMs.) Programs for displaying validity and status
    information and for re-attaching the Vicar label to the EDR are
    also available.
 
 
  Media/Format
  ============
    The NIMS EDRs are archived on CD-ROM for delivery to the
    Planetary Data System (PDS).  Formats are based on standards
    for such products established by PDS.
DATA_SET_RELEASE_DATE 1995-08-30T00:00:00.000Z
START_TIME 1991-10-29T02:33:00.000Z
STOP_TIME 1993-08-30T07:22:00.000Z
MISSION_NAME COMET SL9/JUPITER COLLISION
GALILEO
MISSION_START_DATE 1993-01-01T12:00:00.000Z
1977-10-01T12:00:00.000Z
MISSION_STOP_DATE 1996-01-01T12:00:00.000Z
2003-09-21T12:00:00.000Z
TARGET_NAME GASPRA
IDA
TARGET_TYPE ASTEROID
ASTEROID
INSTRUMENT_HOST_ID GO
INSTRUMENT_NAME NEAR INFRARED MAPPING SPECTROMETER
INSTRUMENT_ID NIMS
INSTRUMENT_TYPE IMAGING SPECTROMETER
NODE_NAME Imaging
ARCHIVE_STATUS ARCHIVED
CONFIDENCE_LEVEL_NOTE
Confidence Level Overview
  =========================
    NIMS EDRs contain essentially raw data as received from Galileo
    telemetry.  These are generally processed into spectral image
    cubes for science analysis.  A fuller discussion of confidence
    levels will be more appropriate for the spectral image cube
    dataset.
 
 
  Review
  ======
    The NIMS EDRs are reviewed prior to archiving by the NIMS team.
    Data received is compared with data expected, and replays of
    missing data requested.  The status and validity information on
    the EDRs themselves is examined, and spikes (bad points) are
    identified.  Spectral image cubes of NIMS target data are
    generated and reviewed for spatial data coverage and
    consistency against observational plans.  Format and
    documentation of the CD-ROM archive volumes are reviewed by
    PDS.
 
 
  Data Coverage and Quality
  =========================
    The EDRs contain flags which indicate the validity of
    individual subsets of NIMS sensor data.  Zeros are used as fill
    values when data is missing or invalid.
 
 
  Limitations
  ===========
    The raw data numbers on the NIMS EDRs are of limited use.
    Proper science analysis requires the computation of radiances
    according to the best understanding of the instrument
    calibration, and proper projection of the data onto the target
    in the form of spectral image cubes.
CITATION_DESCRIPTION Citation TBD
ABSTRACT_TEXT NIMS Experiment Data Record (EDR) files contain raw data from the Galileo Orbiter Near-Infrared Mapping Spectrometer (CARLSONETAL1992). This raw data requires considerable processing before it is readily amenable to science analysis. The EDRs comprise the base dataset from which spectral image cubes will be created by continually evolving software using successively more accurate calibration and geometry data.
PRODUCER_FULL_NAME DR. ROBERT W. CARLSON
SEARCH/ACCESS DATA
  • Imaging Planetary Image Atlas
  • Imaging Online Data Volumes (JPL)
  • Imaging Online Data Volumes (USGS)