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NASA Space Science Data Coordinated Archive Header



Availability: Archived at NSSDC, accessible from elsewhere

Time span: 1990-11-14 to 1990-12-17


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

This data set contains the R_EDR data for the Galileo Orbiter PPR instrument for the period corresponding to the Earth-1 encounter observations in November-December 1990. Data Set Overview ================= As described in the Project Galileo Experiment Data Record Software Interface Specification (cf. ASCII and word processor text versions in DOCUMENT subdirectory), the Galileo Data Management System generates Low Rate Science (LRS) EDR files for eight Galileo Orbiter instruments including the PPR. EDR files are organized into blocks of data corresponding to a major frame, or one RIM (major frame count) cycle consisting of 91 minor frames. The EDR generation program extracts the AACS, PPR science, and science related engineering channels from each LRS minor frame using the spacecraft clock (SCLK) count to control the building of EDR blocks of data. With normal, uninterrupted LRS data, the SCLK count increments through minor frame (MOD91 count) numbers 0 through 90 and then the next minor frame starts a new major frame with the RIM count incremented by one. If LRS minor frames are missing, appropriate locations within the EDR blocks corresponding to these missing data are filled with binary zeros. The MOD91 count and the spacecraft event time (SCET) that corresponds to the first actual (non-filler) minor frame in a block is placed in the header record of that block, thus allowing for missing data at the beginning of the block as well as for the initial block of an EDR file which may begin at a MOD91 count other than 0. The PPR EDR data for a major frame consist of a pair of blocks, the first being 2252 bytes in length and the second, 1924 bytes. At the beginning of the first block is a header of 68 bytes and this is followed by 24 bytes of spacecraft and scan platform attitude data for each of the 91 minor frames of that major frame. The second block of the pair begins with a header of 68 bytes, followed by a subheader of 216 bytes containing science related engineering data and then 18 bytes of PPR housekeeping and science data for each of the 91 minor frames. (Since this total of 1922 bytes is not an integral number of 4-byte words, zero fill for byte numbers 1923 and 1924 is used to complete the second block.) For each of the 18-byte PPR minor frame records, the first six bytes are housekeeping data that completely specify the instrument status, both commanded parameters and position within operational measurement mode cycles. The remaining twelve bytes are three sets of science data sample pairs and their associated identifying parameters. Data files of the present archive are a reformatted version of the PPR EDR data (hence, R_EDR). These files are organized in an ASCII Table format with one record of 51 parameters, or columns, corresponding to each PPR science data sample pair (three per minor frame). In addition to the data number (DN) values for the sample pair itself, all parameters from the PPR housekeeping and supplementary EDR data (including appropriately adjusted time and scan platform pointing information) that identify and characterize that sample pair are included among the 51 parameters. Each data file has an attached PDS label that specifies the record format and describes each parameter of the record. Russell, E.E., F.G. Brown, R.A. Chandos, W.C. Fincher, L.F. Kubel, A.A. Lacis, and L.T. Travis, Galileo Photopolarimeter/Radiometer Experiment, Space Sci. Rev. 60 p. 531-563, 1992. Hunten, D.M., L. Colin and J.E. Hansen, Atmospheric Science on the Galileo Mission, Space Sci. Rev., 44, 191-240, 1986 Johnson, T.V., C.M. Yeates and R. Young, Space Science Reviews Volume on Galileo Mission Overview, Space Sci. Rev., 60, 3-21, 1992

These data are available on-line from the Planetary Data System (PDS) at:

Alternate Names



  • Planetary Science: Fields and Particles

Additional Information



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



NameRoleOriginal AffiliationE-mail
Dr. James E. HansenData ProviderNASA Goddard Institute for Space
Dr. Larry D. TravisGeneral ContactNASA Goddard Institute for Space
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