Rock Abrasion Tool (RAT) data sets

Data Set Overview

This data set contains the primary data that is useful for investigating the mechanical properties of the varied rock types that the rover encountered. During all phases of RAT operations (i.e., calibration, seek-scan, grinding, diagnostic or brush station), the RAT application software stores sensor values and information about the RAT machine state. RAT data products will be comprised of time-ordered data records that include motor positions, motor currents, contact switch states, temperature sensor values, bus voltage, software/algorithm states, error bit fields, etc. Data records will be written to the detailed data product at a nominal rate of 2-Hz. Anomaly reports will include data stored at 8-Hz.

Processing

This data set uses the Committee On Data Management And Computation (CODMAC) data level numbering system. The MER camera Payload EDRs are considered level 2 or Edited Data (equivalent to NASA level 0). The data files are generated from level 1 or Raw Data which are the telemetry packets within the Project-specific Standard Formatted Data Unit (SFDU) record.

RAT EDRs were generated by the MIPL (Multimission Image Processing Laboratory) at JPL under the Operation Products Generation Subsystem using the telemetry processing software mertelemproc. The EDRs are raw uncalibrated data reconstructed from telemetry data products and formatted according to the Camera EDR/RDR Software Interface Specification. Meta-data acquired from the telemetry data headers and a meta-data database were used to propagate the PDS label. There will not be multiple versions of a RAT EDR. If telemetry packets are missing during the initial downlink, the missing data will be identified and reported for retransmission of the data to the ground. The data will be reprocessed after all data is received and the original version will be overwritten.

Data

The structure of the RAT EDR consists of an attached ASCII PDS label and a binary data file. It should be noted that an EDR can be generated with only the PDS label. This will occur when only the telemetry header and no binary data is received.

A RAT EDR consists of a table of time-ordered current, encoder, and temperature measurements for the three RAT motors during a single RAT deployment. A RAT EDR covers a maximum time interval of 6 hours, and has a maximum sampling rate of 8 Hz. Both the sampling rate and time interval are commandable. Each RAT EDR is contained in a separate file. The file is binary with fixed-length records of 96 bytes, and with a PDS label in ASCII text attached to the beginning of the file. The maximum file size is 7.8 Mbytes.

Software

RATViewer is a data analysis tool developed by the RAT Team at Honeybee Robotics. RATViewer will be used by the Team to generate quick-look data products so that RAT health and performance can be assessed in real time. RATViewer facilitates instrument health analysis by comparing downlinked RAT initialization data to calibration data. Both the calibration data and a collection of derived data taken from pre-mission experiments and mission operations simulations are included in the PDS archive of RAT data products.

PDS-labeled images and tables can be viewed with the program NASAView, developed by the PDS and available for a variety of computer platforms from the PDS web site. There is no charge for NASAView.

RATViewer software will be included on RAT archive volumes and will be available for downloading from PDS web sites that distribute RAT data products.

Media/Format

The data set will initially be delivered and kept online. Upon Mission completion, the Rock Abrasion Tool EDRs will be delivered to PDS on DVD as part of the complete MER EDR data set.