Search Publications
The importance of lake breach floods for valley incision on early Mars
Goudge, Timothy A.; Fassett, Caleb I.; Morgan, Alexander M. +1 more
The surface environment of early Mars had an active hydrologic cycle, including flowing liquid water that carved river valleys1-3 and filled lake basins4-6. Over 200 of these lake basins filled with sufficient water to breach the confining topography4,6, causing catastrophic flooding and incision of outlet canyons<…
Supervolcanoes within an ancient volcanic province in Arabia Terra, Mars
Bleacher, Jacob E.; Michalski, Joseph R.
Several irregularly shaped craters located within Arabia Terra, Mars, represent a new type of highland volcanic construct and together constitute a previously unrecognized Martian igneous province. Similar to terrestrial supervolcanoes, these low-relief paterae possess a range of geomorphic features related to structural collapse, effusive volcani…
Subsurface water and clay mineral formation during the early history of Mars
Murchie, Scott L.; Ehlmann, Bethany L.; Mustard, John F. +4 more
Clay minerals, recently discovered to be widespread in Mars's Noachian terrains, indicate long-duration interaction between water and rock over 3.7 billion years ago. Analysis of how they formed should indicate what environmental conditions prevailed on early Mars. If clays formed near the surface by weathering, as is common on Earth, their presen…
Observed variations of methane on Mars unexplained by known atmospheric chemistry and physics
Lefèvre, Franck; Forget, François
The detection of methane on Mars has revived the possibility of past or extant life on this planet, despite the fact that an abiogenic origin is thought to be equally plausible. An intriguing aspect of the recent observations of methane on Mars is that methane concentrations appear to be locally enhanced and change with the seasons. However, metha…
Hydrated silicate minerals on Mars observed by the Mars Reconnaissance Orbiter CRISM instrument
Bibring, J. -P.; Arvidson, R. E.; Langevin, Y. +33 more
Phyllosilicates, a class of hydrous mineral first definitively identified on Mars by the OMEGA (Observatoire pour la Mineralogie, L'Eau, les Glaces et l'Activitié) instrument, preserve a record of the interaction of water with rocks on Mars. Global mapping showed that phyllosilicates are widespread but are apparently restricted to ancient terrains…
Heterogeneous chemistry in the atmosphere of Mars
Montmessin, Franck; Bertaux, Jean-Loup; Perrier, Séverine +6 more
Hydrogen radicals are produced in the martian atmosphere by the photolysis of water vapour and subsequently initiate catalytic cycles that recycle carbon dioxide from its photolysis product carbon monoxide. These processes provide a qualitative explanation for the stability of the atmosphere of Mars, which contains 95 per cent carbon dioxide. Bala…
Early geochemical environment of Mars as determined from thermodynamics of phyllosilicates
Bibring, Jean-Pierre; Poulet, Francois; Chevrier, Vincent
Images of geomorphological features that seem to have been produced by the action of liquid water have been considered evidence for wet surface conditions on early Mars. Moreover, the recent identification of large deposits of phyllosilicates, associated with the ancient Noachian terrains suggests long-timescale weathering of the primary basaltic …
No signature of clear CO2 ice from the `cryptic' regions in Mars' south seasonal polar cap
Forget, F.; Bibring, Jean-Pierre; Langevin, Yves +5 more
The seasonal polar ice caps of Mars are composed mainly of CO2 ice. A region of low (< 30%) albedo has been observed within the south seasonal cap during early to mid-spring. The low temperature of this `cryptic region' has been attributed to a clear slab of nearly pure CO2 ice, with the low albedo resulting from absorptio…
MARSIS radar sounder evidence of buried basins in the northern lowlands of Mars
Stofan, Ellen R.; Clifford, Stephen M.; Safaeinili, Ali +7 more
A hemispheric dichotomy on Mars is marked by the sharp contrast between the sparsely cratered northern lowland plains and the heavily cratered southern highlands. Mechanisms proposed to remove ancient crust or form younger lowland crust include one or more giant impacts, subcrustal transport by mantle convection, the generation of thinner crust by…
Phyllosilicates on Mars and implications for early martian climate
Mangold, N.; Bibring, J. -P.; Arvidson, R. E. +6 more
The recent identification of large deposits of sulphates by remote sensing and in situ observations has been considered evidence of the past presence of liquid water on Mars. Here we report the unambiguous detection of diverse phyllosilicates, a family of aqueous alteration products, on the basis of observations by the OMEGA imaging spectrometer o…