* Astronomy

Title: Comparison of "warm and wet" and "cold and icy" scenarios for early Mars in a 3D climate model
Author: Robin D. Wordsworth, Laura Kerber, Raymond T. Pierrehumbert, Francois Forget, James W. Head

We use a 3D general circulation model to compare the primitive Martian hydrological cycle in "warm and wet" and "cold and icy" scenarios. In the warm and wet scenario, an anomalously high solar flux or intense greenhouse warming artificially added to the climate model are required to maintain warm conditions and an ice-free northern ocean. Precipitation shows strong surface variations, with high rates around Hellas basin and west of Tharsis but low rates around Margaritifer Sinus (where the observed valley network drainage density is nonetheless high). In the cold and icy scenario, snow migration is a function of both obliquity and surface pressure, and limited episodic melting is possible through combinations of seasonal, volcanic and impact forcing. At surface pressures above those required to avoid atmospheric collapse (~0.5 bar) and moderate to high obliquity, snow is transported to the equatorial highland regions where the concentration of valley networks is highest. Snow accumulation in the Aeolis quadrangle is high, indicating an ice-free northern ocean is not required to supply water to Gale crater. At lower surface pressures and obliquities, both H2O and CO2 are trapped as ice at the poles and the equatorial regions become extremely dry. The valley network distribution is positively correlated with snow accumulation produced by the cold and icy simulation at 41.8 degrees obliquity but uncorrelated with precipitation produced by the warm and wet simulation. Because our simulations make specific predictions for precipitation patterns under different climate scenarios, they motivate future targeted geological studies.

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Curiosity Mars Rover Sees Trend in Water Presence

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Last week, the rover's science team announced that analysis of powder from a drilled mudstone rock on Mars indicates past environmental conditions that were favourable for microbial life. Additional findings presented today (March 18) at a news briefing at the Lunar and Planetary Science Conference in The Woodlands, Texas, suggest those conditions extended beyond the site of the drilling. 
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Until now, Earth was the only planet known to have vast reservoirs of water in its interior. Scientists analysed the water content of two Martian meteorites originating from inside the Red Planet. They found that the amount of water in places of the Martian mantle is vastly larger than previous estimates and is similar to that of Earth's. The results not only affect what we know about the geologic history of Mars, but also have implications for how water got to the Martian surface. The data raise the possibility that Mars could have sustained life.
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