The relationship between radar scattering and surface roughness of lunar volcanic features

Abstract

Lunar roughness measurements derived from the Lunar Orbiter Laser Altimeter are compared to 12.6 cm wavelength radar data collected by the Miniature Radio Frequency instrument and 70 cm wavelength radar data collected by the Arecibo Observatory. These data are compared to assess how surface and subsurface roughness are correlated and affected by parameters including age and composition at length scales between 0.1 and 100 m. A range of features are analyzed including volcanic domes (Marius Hills, Rümker Hills, Gruithuisen, and Mairan Domes); mare (Imbrium, Serenitatis, and Oceanus Procellarum); pyroclastic dark mantle deposits (Sinus Aestuum, Sulpicius Gallus, and Mare Vaporum); and two young craters (Copernicus and Tycho). Statistically significant positive correlations exist between topographic roughness and both P-and S-band circular polarization ratios. The strongest correlation is observed at the longest length scales. Correlations weaken as length scales become less similar, potentially due to distinct processes controlling surface modification. Roughness is not significantly correlated with local slope. Although the Marius Hills are compositionally distinct from the Gruithuisen and Mairan domes, they are indistinguishable in roughness characteristics. Conversely, the Rümker Hills, mare, and dark mantle deposits are smoother at the length scales examined, possibly due to fine-grained mantling of regolith or pyroclastic deposits. The floor and ejecta of Tycho are the roughest surfaces measured in this study, while the floor and ejecta of Copernicus overlap the roughness distribution of the volcanic features. This study shows that many factors control the evolution of roughness over time on various length scales.

The role of substrate characteristics in producing anomalously young crater retention ages in volcanic deposits on the Moon: Morphology, topography, subresolution roughness, and mode of emplacement of the Sosigenes lunar irregular mare patch

“…Therefore, we suggest that pyroclastic eruptions are not likely to be responsible for the formation of lunar IMPs, although they may play a role in the initial opening stage of the eruption Head 2016, 2017a;Head and Wilson 2017). Our suggestion is also supported by M 3 spectroscopic observations, which show similar mineralogy for the different morphologic units of IMPs and the surrounding mare basalt deposits, and no detection of glass-bearing materials (Bennett et al 2015;Grice et al 2016), which are often observed in M 3 spectroscopic data of pyroclastic deposits (e.g., Jawin et al 2014).…”

“…), which are often observed in M 3 spectroscopic data of pyroclastic deposits (e.g., Jawin et al. ).…”

Temporal Evolution of S‐Band Circular Polarization Ratios of Kilometer‐Scale Craters on the Lunar Maria

“…Upon a single specular reflection, the polarization flips, so low values of CPR are expected from an area dominated by single reflections, whereas if rocks or roughness lead to multibounce scattering, CPR values of 1 (or more) can occur (e.g., Campbell, 2012;Campbell et al, 2009). Nonetheless, CPR is widely used as an indicator of the rockiness of surface and near-subsurface materials found in different geological settings on the Moon (e.g., Campbell, 2012;Campbell et al, 2007Campbell et al, , 2010Carter et al, 2009;Ghent et al, 2005;Jawin et al, 2014;Neish et al, 2013;Stickle et al, 2016;Thompson et al, 1981Thompson et al, , 2011. Thus, this description of how CPR might be affected by the interaction of the radar wave with a surface is somewhat simplified.…”

“…Thus, this description of how CPR might be affected by the interaction of the radar wave with a surface is somewhat simplified. Nonetheless, CPR is widely used as an indicator of the rockiness of surface and near-subsurface materials found in different geological settings on the Moon (e.g., Campbell, 2012;Campbell et al, 2007Campbell et al, , 2010Carter et al, 2009;Ghent et al, 2005;Jawin et al, 2014;Neish et al, 2013;Stickle et al, 2016;Thompson et al, 1981Thompson et al, , 2011.…”

Study of equatorial regions of Moon with the help of backscattering coefficient obtained from LRO data

“…Radar is one of the few remote sensing tools capable of distinguishing water ice from other forms of water that might be present on the Moon. The SAR data (Jawin et al 2012) is received in the PDS format (Stokes vector). The Mini-RF instrument orbited around the Moon with resolution of 30 m/pixel and two wavelength bands, a primary band at 12.6 cm and a secondary band at 4.2 cm.…”