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Groundwater activity on Mars and implications for a deep biosphere
Michalski, Joseph R.; Niles, Paul B.; Cuadros, Javier +3 more
By the time eukaryotic life or photosynthesis evolved on Earth, the martian surface had become extremely inhospitable, but the subsurface of Mars could potentially have contained a vast microbial biosphere. Crustal fluids may have welled up from the subsurface to alter and cement surface sediments, potentially preserving clues to subsurface habita…
Variations of sulphur dioxide at the cloud top of Venus's dynamic atmosphere
Montmessin, Franck; Bertaux, Jean-Loup; Marcq, Emmanuel +1 more
Sulphur dioxide is a million times more abundant in the atmosphere of Venus than that of Earth, possibly as a result of volcanism on Venus within the past billion years. A tenfold decrease in sulphur dioxide column density above Venus's clouds measured by the Pioneer Venus spacecraft during the 1970s and 1980s has been interpreted as decline follo…
Transport-driven formation of a polar ozone layer on Mars
Montmessin, Franck; Lefèvre, Franck
Since the seasonal and spatial distribution of ozone on Mars was detected by the ultraviolet spectrometer onboard the spacecraft Mariner 7, our understanding has evolved considerably thanks to parallel efforts in observations and modelling. At low-to-mid latitudes, martian ozone is distributed vertically in two main layers, a near-surface layer an…
A chaotic long-lived vortex at the southern pole of Venus
Hueso, R.; Sánchez-Lavega, A.; Drossart, P. +3 more
Polar vortices are common in the atmospheres of rapidly rotating planets. On Earth and Mars, vortices are generated by surface temperature gradients and their strength is modulated by the seasonal insolation cycle. Slowly rotating Venus lacks pronounced seasonal forcing, but vortices are known to occur at both poles, in an atmosphere that rotates …