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National Aeronautics and Space Administration Goddard Space Flight Center |
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 MOLA |
MOLA sends back a great deal of information besides the direct ranges. The Aggregated Experiment Data Records (AEDRs) are a Level 0 product, produced directly from downlink telemetry. These are binary files containing one data record every 14 seconds. The full description of the instrument data stream is contained in the AEDR Software Interface Specification V.2.1, also available in PDF format.
Level 1 processing takes these records and applies calibration factors to output results in physical units. The output format is again binary, with one record for each 20-shot (approximately two seconds) data frame. In order to interpret these records as altimetric profiles, precision orbit information is merged to locate each shot on the planet and determine its radius at that spot. An equipotential reference surface representing a "sea level" datum is provided for each shot, based on our best knowledge of the martian gravity field. The radius minus the datum (areoid) is the topography.
The level 1 product is described in the PEDR Software Interface Specification V.2.8. Users may also download a PDF version of the PEDR SIS V.2-7.
In order to compress this information into a manageable volume, much of the information is recorded only once per frame, and must be interpolated to the time of the shot. The format is generally an unsigned integer or a two's complement signed integer of length 1, 2, or 4 bytes. These are represented in a "big-endian" order, and various bytes must be swapped to read them on "small-endian" computers such as PCs. This work is not particularly interesting to the planetary scientist and so we are making available various programs to read the PEDR's and output "flat" ASCII-encoded text files, or "spreadsheets", one line per shot. These programs are unsupported, but we hope that they will meet your needs.
Description of the available platforms and files
The following directories contain source code and executables:
