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Organic salts, such as Fe, Ca, and Mg oxalates and acetates, may be widespread radiolysis and oxidation products of organic matter in Martian surface sediments. Such organic salts are challenging to identify by evolved gas analysis but the ubiquitous CO2 and CO in pyrolysis data from the Sample Analysis at Mars (SAM) instrument suite on the Curiosity rover indirectly points to their presence. Here, we examined laboratory results from SAM‐like analyses of organic salts as pure phases, as trace phases mixed with silica, and in mixtures with Ca and Mg perchlorates. Pure oxalates evolved CO2 and CO, while pure acetates evolved CO2 and a diverse range of organic products dominated by acetone and acetic acid. Dispersal within silica caused minor peak shifting, decreased the amounts of CO2 evolved by the acetate standards, and altered the relative abundances of the organic products of acetate pyrolysis. The perchlorate salts scrubbed Fe oxalate CO releases and shifted the CO2 peaks to lower temperatures, whereas with Ca and Mg oxalate, a weaker CO release was observed but the initial CO2 evolutions were largely unchanged. The perchlorates induced a stronger CO2 release from acetates at the expense of other products. Oxalates evolved ∼47% more CO2 and acetates yielded ∼69% more CO2 when the perchlorates were abundant. The most compelling fits between our organic salt data and SAM CO2 and CO data included Martian samples acquired from modern eolian deposits and sedimentary rocks with evidence for low‐temperature alteration.

Organic salts, such as Fe, Ca, and Mg oxalates and acetates, may be widespread radiolysis and oxidation products of organic matter in Martian surface sediments. Such organic salts are challenging to identify by evolved gas analysis but the ubiquitous CO2 and CO in pyrolysis data from the Sample Analysis at Mars (SAM) instrument suite on the Curiosity rover indirectly points to their presence. Here, we examined laboratory results from SAM‐like analyses of organic salts as pure phases, as trace phases mixed with silica, and in mixtures with Ca and Mg perchlorates. Pure oxalates evolved CO2 and CO, while pure acetates evolved CO2 and a diverse range of organic products dominated by acetone and acetic acid. Dispersal within silica caused minor peak shifting, decreased the amounts of CO2 evolved by the acetate standards, and altered the relative abundances of the organic products of acetate pyrolysis. The perchlorate salts scrubbed Fe oxalate CO releases and shifted the CO2 peaks to lower temperatures, whereas with Ca and Mg oxalate, a weaker CO release was observed but the initial CO2 evolutions were largely unchanged. The perchlorates induced a stronger CO2 release from acetates at the expense of other products. Oxalates evolved ∼47% more CO2 and acetates yielded ∼69% more CO2 when the perchlorates were abundant. The most compelling fits between our organic salt data and SAM CO2 and CO data included Martian samples acquired from modern eolian deposits and sedimentary rocks with evidence for low‐temperature alteration.

The texture, composition, and morphology of dunes observed in the equatorial regions of Titan may reflect present and/or past climatic conditions. Determining the physio‐chemical properties and the morphodynamics of Titan's dunes is therefore essential to understanding of the climatic and geological history of the largest moon of Saturn. We quantitatively derived average surface properties of dune and interdune areas (texture, composition) from modeling of the microwave backscattered signal and Monte‐Carlo inversion of the despeckled Cassini/SAR data over Titan's three largest sand seas: Belet, Shangri‐La and Fensal. We present the first analysis of the backscatter functions extracted from despeckled SAR images that cover such a large range in incidence angles, including data from the beginning of the Cassini mission up to its Grand Finale. We show that dunes and interdunes have significantly different physical properties. Dunes are found to be more microwave absorbent than interdunes. Additionally, potential secondary bedforms, such as ripples and avalanches, may have been detected, providing potential evidence for currently active dunes and sediment transport. Our modelling shows that the interdunes have multi‐scale roughnesses with higher dielectric constants than the dunes which have a low dielectric constant consistent with organic sand. The radar brightness of the interdunes can be explained by the presence of a shallow layer of significantly larger organic grains, possibly non‐mobilized by the winds. Together, our findings suggest that Titan's sand seas evolve under the current multi‐directional wind regimes with dunes that elongate with their crests aligned in the residual drift direction.

The texture, composition, and morphology of dunes observed in the equatorial regions of Titan may reflect present and/or past climatic conditions. Determining the physio‐chemical properties and the morphodynamics of Titan's dunes is therefore essential to understanding of the climatic and geological history of the largest moon of Saturn. We quantitatively derived average surface properties of dune and interdune areas (texture, composition) from modeling of the microwave backscattered signal and Monte‐Carlo inversion of the despeckled Cassini/SAR data over Titan's three largest sand seas: Belet, Shangri‐La and Fensal. We present the first analysis of the backscatter functions extracted from despeckled SAR images that cover such a large range in incidence angles, including data from the beginning of the Cassini mission up to its Grand Finale. We show that dunes and interdunes have significantly different physical properties. Dunes are found to be more microwave absorbent than interdunes. Additionally, potential secondary bedforms, such as ripples and avalanches, may have been detected, providing potential evidence for currently active dunes and sediment transport. Our modelling shows that the interdunes have multi‐scale roughnesses with higher dielectric constants than the dunes which have a low dielectric constant consistent with organic sand. The radar brightness of the interdunes can be explained by the presence of a shallow layer of significantly larger organic grains, possibly non‐mobilized by the winds. Together, our findings suggest that Titan's sand seas evolve under the current multi‐directional wind regimes with dunes that elongate with their crests aligned in the residual drift direction.