* Astronomy

Blobrana · L

RE: Mars

Blobrana · L

Title: Variability of the methane trapping in martian subsurface clathrate hydrates
Authors: Caroline Thomas, Olivier Mousis, Sylvain Picaud, Vincent Ballenegger

Recent observations have evidenced traces of methane CH4 heterogeneously distributed in the martian atmosphere. However, because the lifetime of CH4 in the atmosphere of Mars is estimated to be around 300-600 years on the basis of photochemistry, its release from a subsurface reservoir or an active primary source of methane have been invoked in the recent literature. Among the existing scenarios, it has been proposed that clathrate hydrates located in the near subsurface of Mars could be at the origin of the small quantities of the detected CH4. Here, we accurately determine the composition of these clathrate hydrates, as a function of temperature and gas phase composition, by using a hybrid statistical thermodynamic model based on experimental data. Compared to other recent works, our model allows us to calculate the composition of clathrate hydrates formed from a more plausible composition of the martian atmosphere by considering its main compounds, i.e. carbon dioxyde, nitrogen and argon, together with methane. Besides, because there is no low temperature restriction in our model, we are able to determine the composition of clathrate hydrates formed at temperatures corresponding to the extreme ones measured in the polar caps. Our results show that methane enriched clathrate hydrates could be stable in the subsurface of Mars only if a primitive CH4-rich atmosphere has existed or if a subsurface source of CH4 has been (or is still) present.

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Blobrana · L

Mars craters might be scars from fallen moon
An unusual pair of craters on Mars formed when a moon broke apart before crashing into the planet's surface about a billion years ago, a new study suggests.
The craters could hint at what lies in store for Phobos, a potato-shaped moon that is expected to smash into Mars millions of years from now.
The two craters, which lie about 12.5 kilometres apart, share the same oval shape and nearly the same west-east alignment.
Similar crater pairs are seen elsewhere, including a duo called "Messier" on the Moon. The Messier craters may have formed from a pair of orbiting asteroids that crashed to the surface together at a low impact angle.
But John Chappelow and Rob Herrick of the University of Alaska, Fairbanks, say there is only a 2% chance that the two craters on Mars formed that way.

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Martian Crater Named Endeavour

Blobrana · L

RE: Mars

Blobrana · L

rugged highland material in an area near the Martian equator

A September 2008 release of 1,575 new images, such as this one, from the Compact Reconnaissance Imaging Spectrometer (CRISM) on NASA's Mars Reconnaissance Orbiter brings the number of released, high-resolution CRISM images to 4,580. More about this new batch of images can be found at HERE. This image in enhanced color from visible-light wavelengths shows light-toned rugged highland material in an area near the Martian equator. It covers an area about 10 kilometers or 6 miles wide.

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Clouds of water ice drifting above the Martian surface eat up some of the ozone in Mars' atmosphere, a new study suggests, giving scientists new clues about the chemical environment and climate of Earth's nearest neighbour.
Mars has a relatively stable atmosphere that is 95 percent carbon dioxide (Earth's atmosphere is only 0.04 percent carbon dioxide).
Scientists have had a difficult time modelling certain aspects of Mars' atmosphere and some suspected that reactions between atmospheric gases and ice cloud particles could account for the differences between their models and satellite observations, particularly of ozone concentrations.

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The IAU has approved the name Bogia for the Martian crater at 44.3S, 276.84W.

Blobrana · L

"Mars is not a dead planet -it undergoes climate changes that are even more pronounced than on Earth" - James Head, planetary geologist, Brown University

The prevailing thinking is that Mars is a planet whose active climate has been confined to the distant past. About 3.5 billion years ago, the Red Planet had extensive flowing water and then fell quiet - deadly quiet. It didn't seem the climate had changed much since. Now, recent studies by scientists at Brown University show that Mars' climate has been much more dynamic than previously believed.

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A group of astronomers in Canada have suggested that an orbiting asteroid may have switched Mars's magnetic field on and off like a light switch.
Mars once had a magnetic field, which may have been driven by a dynamo formed from the convection of material in the core, much like the Earth's is today. Yet crater records suggest the Martian dynamo died quickly, over a few tens of thousands of years, something researchers struggle to explain.

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