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NASA Space Science Data Coordinated Archive Header

MRO SHARAD EXPERIMENT DATA RECORD V1.0 (PDS)

NSSDCA ID: PSPG-00884

Availability: Archived at NSSDC, accessible from elsewhere

Description

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

Data Set Overview

Data Set MARS RECONNAISSANCE ORBITER MARS SHARAD EXPERIMENT DATA RECORD V1.0 (Level 1-A data) consists of the instrument telemetry correlated with the auxiliary information needed to locate observations in space and time and to process data further. Level 1-A data users will mainly be radar scientists interested in redoing the entire processing of the received signal. The fact that unprocessed Subsurface Sounding echoes do not show any obvious indication of subsurface interfaces will make EDRs of little use for geologists. The reader is referred to the SHARAD RDR data set (MRO-M-SHARAD-4-RDR-V1.0) for calibrated, processed SHARAD data suitable for science analysis. Processing ========== SHARAD EDR Data Products are generated at the SHARAD operation center in Rome, Italy, under the responsibility of the Team Leader Institution (INFOCOM Department, University of Rome 'La Sapienza'). To produce EDRs, data are ordered in time and sorted by instrument operative mode. Any duplicate packets are removed, while missing and corrupted packets are accounted for and substituted by zeropadding. Level 1A processing consists of the following functions: 1) Deformatting data packets 2) Time ordering data packets 3) Sorting data packets by instrument operative mode 4) Testing quality of data packets 5) Formatting data packets into binary files 6) Generating auxiliary data to locate each observation in space and time 7) Generating PDS detached labels for data products Apart from editing of data to remove duplicates and transmission errors, no processing is applied to the scientific data of the instrument. Calibration information is provided in the form of calibration files containing the transfer function of the instrument. Input for Level 1A processing consists of: 1) SHARAD science telemetry in the form of Instrument Raw Science Products. 2) SHARAD engineering telemetry. 3) Spacecraft housekeeping telemetry. 4) Ancillary information on spacecraft trajectory and orientation in the form of SPICE SPK and CK kernels produced by the Navigation and Ancillary Information Facility (NAIF) at JPL. 5) Spacecraft clock coefficients to convert spacecraft clock counts into Coordinated Universal Time (UTC), in the form of SPICE SCLK kernels produced by NAIF. Data ==== Each SHARAD Data Product is an aggregation of SHARAD data blocks. A data block is produced through the processing of one or more received echoes, and constitutes a single observation of the instrument. Each Data Product contains data from one or more data blocks collected continuously using the same operation mode, instrument status and on-board processing scheme; that is, using a single OST line. The content of each SHARAD data product is highly variable in terms of number of data blocks, and depends on how operations for the instrument were planned during a given data collection period. Because each data block is a sequence of time samples of a received signal, complemented by ancillary information, the natural organization for data blocks within a Data Product is a table, in which each line contains data from a single data block, and each column contains the value of a single parameter or time sample across different data blocks. Each Data Product consists of three files: 1) A binary file containing the scientific telemetry of the instrument. This is a sequence of echoes, each of which is preceded by a header containing information on the collection and on-board processing of the data. This file is called the Science Telemetry file. 2) A binary table containing geometric quantities generated onground from spacecraft navigation data, parameters extracted from instrument and spacecraft housekeeping telemetry, and flags describing the completeness and usability of the associated scientific telemetry. This file is called the Auxiliary Data file and contains one record for every data block in the Science Telemetry file. 3) A detached ASCII label file describing the content of the data product. The label is written according to standards defined by the Planetary Data System (PDS), and lists parameters describing both the observation in which data were acquired and the structure of the files in which data are stored. Binary files are structured as PDS Table data objects. The content of such tables is listed in format files, of which several exist according to operation mode, instrument status and on-board processing scheme, and which will be contained in the LABEL directory of the Data Set Volume. Ancillary Data ============== Each Auxiliary Data file contains a binary table with one row for each record in the corresponding Science Telemetry file of an EDR data product. Columns of the table are described in a separate file called format file. Coordinate System ================= SHARAD EDR data products conform to a Project-determined set of cartographic standards. All map-projected data use planetocentric coordinates and east-positive longitudes in the range 0 to 360 degrees, computed w.r.t. the IAU 2000 reference ellipsoid. Vector quantities such as spacecraft positions are expressed in a Cartesian planetocentric reference frame. Media/Format ============ Each SHARAD EDR data product consists of two binary files in fixed record-length format, called respectively the Science Telemetry and the Auxiliary Data files. The structure of such files is described by a separate PDS label containing also information on source data, production process, relation between stored bytes and physical quantities, product identification, storing and organizing of ancillary data and descriptive information needed to interpret and process the data. The data contained in the Science Telemetry file and in the Auxiliary Data files are structured as a PDS Table object. The PDS label contains pointers to files containing definitions of the columns of such Table objects. Each record in a binary Science Telemetry file is a Science Data Format, some internal telemetry counters, the Start of Telemetry and End of Telemetry markers, and the checksum. It thus consists of an ancillary data header reporting the OST line used in collecting the data block, ancillary data reporting the time of acquisition of the data and listing parameter values used in processing the data block, and the data block itself, consisting of 3600 echo samples, each either 4-, 6- or 8-bits long. The resulting record length in bytes is thus dependent of the Operational Mode through which data were acquired. Each record in a binary Auxiliary Data file is the line of a table listing values of geometric and engineering parameters relevant for the location and processing of the corresponding data block in the Science Telemetry file. Most parameter values are expressed as an 8-byte or 4-byte IEEE real numbers. Values contained in this file are partly computed from SPICE kernels containing information on spacecraft trajectory and attitude, and partly extracted from SHARAD housekeeping telemetry. PDS labels are written in Object Description Language (ODL). PDS label statements have the form of 'keyword = value'. Each label statement is terminated with a carriage return character (ASCII 13) and a line feed character (ASCII 10) sequence to allow the label to be read by many operating systems.

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

http://pds-geosciences.wustl.edu/mro/mro-m-sharad-3-edr-v1/

Alternate Names

  • MRO-M-SHARAD-3-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. David R. Williams

 

Personnel

NameRoleOriginal AffiliationE-mail
Dr. Roberto SeuData ProviderUniversita degli Studi di Romarobseu@infocom.uniroma1.it
Dr. Roberto OroseiGeneral ContactIstituto Nazionale di Astrofisicaroberto.orosei@iaps.inaf.it
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