NSSDCA ID: PSPG-00900
Availability: At NSSDC, Ready for Electronic Access
This description was generated automatically using input from the Planetary Data System.
The Mars Express Mars Advanced Radar for Subsurface and Active Ionospheric Sounding (MARSIS) data set includes all spectral information calibrated in units of spectral density for the Active Ionospheric Sounder over the third extended Mars Express mission. This data set includes calibrated values for each transmit event and the corresponding temporal data for each frequency channel.
This data set comprises the electric field spectral densities obtained via the electric dipole antenna sensor.
Data in this data set were processed by the use of a number of software programs. These programs re-assembled and de-compressed the raw telemetry data. These raw values were then calibrated into physical units: power received by the electric antenna. The data products were calibrated using the best calibration tables and algorithms available at the time of data archiving. Should a significant improvement in calibration become available, an erratum will be noted in the erratum section. Later versions of the products may contain better calibrations.
The AIS calibrated full resolution data set includes several binary tables of wave spectra as a function of time from each of the various transmit events. Each table will contain fixedlength records including columns for time, transmit frequency, and spectral densities from the temporal measurements. The number of transmit frequencies is constant at 160 frequencies per frame.
The data in this data set are measurements of wave electric fields measured by the MARSIS electric sensors. These fields are presented as detected by the sensors and are not rotated into any other coordinate system. If desired the SPICE kernels can be used with the SPICE toolkit to convert from the spacecraft frame to virtually any frame which may be of use in analyzing these data. However, for many purposes, the wave amplitudes are extremely useful and may be entirely adequate with no coordinate transformations at all.
Sample code is provided with these data which demonstrates how to read these files in order to build a set of time-ordered wave spectra. The sample code and algorithms are found in the SOFTWARE directory.
This data set contains all active ionospheric calibrated data for the Mars Express MARSIS for the interval described above. Every effort has been made to ensure that all data returned to Iowa from the spacecraft is included and that the calibration is accurate.
The MARSIS active ionospheric sounder data will be reviewed internally by the Mars Express MARSIS team prior to release to the PDS. The data set will also be peer reviewed by the PDS.
All data in the stated interval are included to the best of our knowledge and attempts to determine completeness. In general, the instrument was operated only briefly during early cruise phase for the purpose of Antenna deployment and periodic instrument health. During this time, flight restrictions precluded any transmit events and hence no science data. Beginning in June of 2005 commissioning of the instrument commenced more-or-less continuously for about a month. During this period instrument gain settings and transmit frequencies were optimized for maximum signal-to-noise ratios as well as avoidance of interference generated by the spacecraft and by other instruments.
One measurement quality issue deals with the data compression algorithm used by the MARSIS onboard processor, which generates values of zero when the measured AIS values should be small but non-zero.
These data are available on-line from the Planetary Data System (PDS) at:
http://pds-geosciences.wustl.edu/MEX/mex-m-marsis-3-rdr-ais-ext3-v1/mexmdi_1004/
Questions and comments about this data collection can be directed to: Dr. David R. Williams
Name | Role | Original Affiliation | |
---|---|---|---|
Mr. Jeffrey J. Plaut | Data Provider | NASA Jet Propulsion Laboratory | plaut@mail1.jpl.nasa.gov |
Mr. Richard L. Huff | General Contact | University of Iowa | rlh@space.physics.uiowa.edu |