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GALILEO NIMS EXPERIMENT DATA RECORDS: JUPITER OPERATIONS (PDS)

NSSDCA ID: PSPG-00815

Availability: Data Identified but not Received

Description

This description was generated automatically using input from the Planetary Data System.

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. During cruise, these were interleaved with NIMS background and housekeeping values, and, less frequently, various instrument temperatures, AACS (scan platform and rotor pointing) data and engineering measurements. For Jupiter observations, only the sensor values are in the EDR. Those engineering and AACS values which are still being returned are collected in separate datasets. 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. During cruise, they were divided into files containing up to 100 RIMs (60 2/3 second intervals) of data. During Jupiter operations, a separate EDR is generated for each NIMS observation. Each file contains the best data available from the several ground stations receiving Galileo telemetry. Data During cruise, the data were 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. Due to the failure to deploy the Galileo high gain antenna, procedures were developed for editing NIMS data from Jupiter observations in wavelength and/or mirror position, and for lossless compression of the data before playback. (The data are, however, decompressed before the EDR is written.) Thus for Jupiter (phase 2) operations, the EDR format was revised: one record is written for each *half* minor frame of spacecraft clock time, except that no record is written for a half minor frame during which no data is selected. A valid-data mask in the binary header indicates which records in a RIM are actually present. A detailed description of the structure of the EDR may be found in the Galileo Software Interface Specification (ZAMANI1991 for cruise, KAMP1996 for Jupiter operations). 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. 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 and each observation, a digitized map of the Galileo booms in cone-clock space and tables of NIMS internal geometry and timing. Separate files of NIMS engineering values (mostly temperatures) are also included. Tables of (noise) spikes in time order have been developed for Europa, Ganymede and Callisto observations and are also included on the CD-ROM. Calibration and dark value files, and SPICE files (spacecraft positions, planetary positions and constants, processed pointing geometry, spacecraft clock versus universal time, etc.) will be included in later volumes of the CD-ROM set, or in a separate CD-ROM. Presently, calibration and dark value files required for cube generation may be obtained from the NIMS team, and SPICE files may be obtained from the Galileo Science Data Team. Software Simple software is available from the NIMS team 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 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. These data are available on-line from the Planetary Data System (PDS) at: ftp://pdsimage2.wr.usgs.gov/PDS_Archive/Galileo/NIMS/go_1008/

Alternate Names

  • GO-A-NIMS-2-EDR-V1.0
  • GO-E/L-NIMS-2-EDR-V1.0
  • GO-J-NIMS-2-EDR-V1.0
  • GO-J-NIMS-2-EDR-V2.0
  • GO-V-NIMS-2-EDR-V1.0

Discipline

  • Planetary Science: Geology and Geophysics

Additional Information

Spacecraft

Experiments

Questions and comments about this data collection can be directed to: Dr. Edwin V. Bell, II

 

Personnel

NameRoleOriginal AffiliationE-mail
Dr. Robert MehlmanGeneral ContactUniversity of California, Los Angelesjmeans@igpp.ucla.edu
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