MRO SHARAD Surface Clutter Simulations

SHSIMU – SHARAD Surface Clutter Simulations

Instrument:Shallow Radar

PDS4 Bundle:urn:nasa:pds:mro_sharad_simulationsDOI: 10.17189/nbdh-2k53

The MRO SHARAD surface clutter simulations (SCSs) in this dataset are forward models of backscattered power from an interface illuminated by a radar. For this archive, the interface is the surface of Mars as measured by the Mars Orbiter Laser Altimeter (MOLA) instrument on the Mars Global Surveyor (MGS) and the radar is SHARAD. SCSs are an important interpretation aid for orbital sounding radar data. Often the data products from instruments like SHARAD are thought of as two dimensional profiles of the subsurface, however they frequently contain a significant amount of “out-of-plane” power backscattered by off-nadir surface features. The out-of-plane power arrives at longer travel times than the primary surface reflection, mimicking the appearance of subsurface interfaces in the resulting radar data. SCSs attempt to model all reflections that would be generated by the surface, allowing a radar data interpreter to discern power reflected by off-nadir surface features from true subsurface features.

These SCSs are meant to be used with the derived data products created by the United States SHARAD Science Team (USRDR) (Campbell 2014). Other data products, such as the Experiment Data Record (EDR) products and Italian Operations Team derived data products have processing differences that will make comparison with these simulations difficult or impossible.

Because the backscattered power is not accurately modeled, the simulated clutter cannot be subtracted from the radar data to remove it. However, the SCSs have the same dimensions as the radar images, enabling an overlay for qualitative comparison. See Section 3.2 of SHARAD Surface Clutter Simulations User’s Guide.for more information.

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Data Archives

The data products are in the "data" directory and the browse products are in the "browse" directory. The document products are in the "document" directory. The document collection contains a user guide for this archive and a "script" directory with several Python 3 programs demonstrating basic manipulation of the surface clutter simulation data products. The user guide is provided as a PDF formatted document containing both text and figures.

The data and browse directory structures follow the structure of the original PDS3 SHARAD radargram data set, MRO-M-SHARAD-5-RADARGRAM-V1.0:

data/s_NNNNxx/s_NNNNZZZZ/*

For each original radargram, the data collection contains three data products and five browse products, each described by a PDS4 XML label:

- X_sim.xml describes X_sim.img

- X_emap.xml describes X_emap.img

- X_rtrn.xml describes X_rtrn.csv

- X_browse_map.xml describes X_browse_hillshade.tif, and X_browse_emap.tif

- X_browse_sim.xml describes X_browse_left.tif, X_browse_right.tif, X_browse_combined.tif

where

X = "s_01294501" for example, corresponding to radargram s_01294501_rgram.img

X_sim.img contains three 2D images, the left side, right side, and combined clutter simulations

X_emap.img contains one 2D echo power map image

X_browse_*.tif are browse images in TIFF format

X_browse_combined.tif is combined (left and right side) clutter simulation browse product

X_browse_right.tif is right side clutter simulation browse product

X_browse_left.tif is left side clutter simulation browse product

X_browse_emap.tif is echo power map browse product

X_browse_hillshade.tif is hillshaded topography browse product

X_rtrn.csv is a CSV (comma-separated value) text table of geometric information.

More information about MRO SHARAD surface clutter simulation data products can be found in:

  • Choudhary, Prateek, John W. Holt, and Scott D. Kempf (2016), Surface Clutter and Echo Location Analysis for the Interpretation of SHARAD Data From Mars. IEEE Geoscience and Remote Sensing Letters 13 (9): 1285–1289. doi:10.1109/LGRS.2016.2581799.

  • Holt, John W., Matthew E. Peters, Scott D. Kempf, David L. Morse, and Donald D. Blankenship (2006), Echo source discrimination in single-pass airborne radar sounding data from the Dry Valleys, Antarctica: Implications for orbital sounding of Mars. Journal of Geophysical Research: Planets 111 (E6). doi:10.1029/2005JE002525. https://doi.org/10.1029/2005JE002525.

  • Russo, Federica, Marco Cutigni, Roberto Orosei, Carlo Taddei, Roberto Seu, Daniela Biccari, Emanuele Giacomoni, Oreste Fuga, and Enrico Flamini (2008), An incoherent simulator for the SHARAD experiment. doi:10.1109/RADAR.2008.4720761. https://doi.org/10.1109/RADAR.2008.4720761.

  • The User's Guide of SHARAD Surface Clutter Simulations.