SHARAD - Cluttegram

A Matlab function that generates cluttegrams for SHARAD based on x,y,z topography and SHARAD's orbit

A Matlab function that generates cluttergrams for SHARAD based on x,y,z topography data and SHARAD's orbit.

In the github repository there are some examples .txt files with SHARAD's orbit and some topography data from MOLA

https://github.com/IraGia/SHARAD---Cluttergram

Ground-Penetrating Radar (GPR) is an ideal tool for imaging the subsurface of planetary bodies due to its high resolution, continuous measurement capability, and ability to operate in dry, low-conductivity environments. As a result, both satellite and in-situ radars are becoming mainstream geophysical approaches for imaging terrestrial planets, with four active radar sounders (SHARAD, MARSIS, Tianwen-1, SELENE) [1] and three in-situ GPR systems (Chang'E-4, Tianwen-1, Perseverance) [2]. Data from satellite orbiters have been successfully used for mapping subglacial water on Mars and detecting Lunar and Martian caves [3]. Caves such as lava tubes, piping caves, and sub-ice volcanic caves are unique geological structures of great importance in planetary science [3]. Unlike exposed surfaces, caves are shielded environments protected from physicochemical decay and isolated from strong fluxes of ultraviolet cosmic and solar ionizing radiation [3]. For these reasons, caves are ideal places for searching for evidence of current and past life and for potential human habitation and planetary bases [3].

Detecting and mapping planetary subsurface structures requires processing and interpreting a large volume of radar data in a semi-automatic manner. Despite the plethora of available data from radar orbiters, interpretation remains challenging because radargrams are often corrupted with surface reflections that mask signatures from subsurface targets [4]. Therefore, the first and most important processing step is generating a cluttergram that simulates the surface reflections expected in the area of interest. These reflections are then filtered out, enhancing and isolating the radar signatures of subsurface targets [4]. In this function we use the approahc described in [5], with the addition of incorporating the directivity pattern of a dipole in the calculations.

This project was supported by Royal Society of Edinburgh (RSE).

[1] Xu, Y., Cummer, S. A., Farrell, W. M., “Application of an orbital radar sounder model to detecting Martian polar subsurface features,” Journal of Geophysical Research, vol. 111, pp. E06S17.

[2] Hamran, S.-E., Paige, D. A., Amundsen, H. E. F., et al., "Radar Imager for Mars’ Subsurface Experiment—RIMFAX," Space Science Reviews, vol. 216, 128, 2020.

[3] Sam, L., Bhardwaj, A., Singh, S., Martin-Torres, F. J., et al., “Small Lava Caves as Possible Exploratory Targets on Mars: Analogies Drawn from UAV Imaging of an Icelandic Lava Field,” Remote Sensing, vol. 12, pp. 1970, 2020.

[4] Ilyushin, Y. A., Orosei, R., Witasse, O., Sánchez-Cano, B., "CLUSIM: A synthetic aperture radar clutter simulator for planetary exploration," Radio Science, vol. 52, pp. 1200–1213, 2017.

[5] Choudhary, P., Holt, J. W., Kempf, S. D., "Surface Clutter and Echo Location Analysis for the Interpretation of SHARAD Data From Mars," IEEE Geoscience and Remote Sensing Letters, vol. 13, pp. 1285–1289, 2016.