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Post Info TOPIC: Martian Atmosphere


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NASA's MAVEN Reveals Mars Has Metal in its Atmosphere

"MAVEN has made the first direct detection of the permanent presence of metal ions in the ionosphere of a planet other than Earth," said Joseph Grebowsky of NASA's Goddard Space Flight Center in Greenbelt, Maryland. "Because metallic ions have long lifetimes and are transported far from their region of origin by neutral winds and electric fields, they can be used to infer motion in the ionosphere, similar to the way we use a lofted leaf to reveal which way the wind is blowing." Grebowsky is lead author of a paper on this research appearing April 10 in Geophysical Research Letters.
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Mars' Atmosphere
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NASA's MAVEN Reveals Most of Mars' Atmosphere Was Lost to Space

Solar wind and radiation are responsible for stripping the Martian atmosphere, transforming Mars from a planet that could have supported life billions of years ago into a frigid desert world, according to new results from NASA's MAVEN spacecraft.
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Title: Transient reducing greenhouse warming on early Mars
Author: Robin Wordsworth, Yulia Kalugina, Sergei Lokshtanov, Andrei Vigasin, Bethany Ehlmann, James Head, Cecilia Sanders, Huize Wang

The evidence for abundant liquid water on early Mars despite the faint young Sun is a long-standing problem in planetary research. Here we present new ab initio spectroscopic and line-by-line climate calculations of the warming potential of reduced atmospheres on early Mars. We show that the strength of both CO2-H2 and CO2-CH4 collision-induced absorption (CIA) has previously been significantly underestimated. Contrary to previous expectations, methane could have acted as a powerful greenhouse gas on early Mars due to CO2-CH4 CIA in the critical 250-500 cm^-1 spectral window region. In atmospheres of 0.5 bar CO2 or more, percent levels of H2 or CH4 raise annual mean surface temperatures by tens of degrees, with temperatures reaching 273 K for pressures of 1.25-2 bar and 2-10% of H2 and CH4. Methane and hydrogen produced following aqueous alteration of Mars' crust could have combined with volcanically outgassed CO2 to form transient atmospheres of this composition 4.5-3.5 Ga. This scenario for the late Noachian climate can be tested via future in situ and orbital studies of the martian crust.

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Curiosity Finds Evidence of Mars Crust Contributing to Atmosphere

NASA's Curiosity rover has found evidence that chemistry in the surface material on Mars contributed dynamically to the makeup of its atmosphere over time. It's another clue that the history of the Red Planet's atmosphere is more complex and interesting than a simple legacy of loss.
The findings come from the rover's Sample Analysis at Mars, or SAM, instrument suite, which studied the gases xenon and krypton in Mars' atmosphere. The two gases can be used as tracers to help scientists investigate the evolution and erosion of the Martian atmosphere. A lot of information about xenon and krypton in Mars' atmosphere came from analyses of Martian meteorites and measurements made by the Viking mission.

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Title: Record of the ancient martian hydrosphere and atmosphere preserved in zircon from a martian meteorite
Author: A. A. Nemchin, M. Humayun, M. J. Whitehouse, R. H. Hewins, J-P. Lorand, A. Kennedy, M. Grange, B. Zanda, C. Fieni & D. Deldicque

Mars exhibits ample evidence for an ancient surface hydrosphere. The oxygen isotope compositions of carbonate minerals and alteration products in martian meteorites suggest that this ancient hydrosphere was not in isotopic equilibrium with the martian lithosphere. Martian meteorite NWA 7533 is composed of regolith breccia from the heavily cratered terrains of ancient Mars and contains zircon grains for which U-Pb ages have been reported. Here we report variations between the oxygen isotopic compositions of four zircon grains from NWA 7533. We propose that these variations can be explained if the mantle melts from which the zircon crystallised approximately 4.43 Gyr ago had assimilated 17O-enriched regolith materials, and that some of the zircon grains, while in a metamict state, were later altered by low-temperature fluids near the surface less than 1.7 Gyr ago. Enrichment of the martian regolith in 17O before the zircon crystallised, presumably through exchange with the 17O-enriched atmosphere or hydrosphere during surface alteration, suggests that the thick primary atmosphere of Mars was lost within the first 120 Myr after accretion. We conclude that the observed variation of 17O anomalies in zircon from NWA 7533 points to prolonged interaction between the martian regolith, atmosphere and hydrosphere.

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Mars had oxygen-rich atmosphere 4000m years ago

Differences between Martian meteorites and rocks examined by a NASA rover can be explained if Mars had an oxygen-rich atmosphere 4000 million years ago - well before the rise of atmospheric oxygen on Earth 2500m years ago.
Scientists from Oxford University investigated the compositions of Martian meteorites found on Earth and data from NASA's 'Spirit' rover that examined surface rocks in the Gusev crater on Mars. The fact that the surface rocks are five times richer in nickel than the meteorites was puzzling and had cast doubt on whether the meteorites are typical volcanic products of the red planet.

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Mars Atmosphere
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Title: Constraints on early Mars atmospheric pressure inferred from small ancient craters
Authors: Edwin S. Kite, Jean-Pierre Williams, Antoine Lucas, Oded Aharonson

The single most important control on long-term climate change on Mars is thought to be decay of the CO2-dominated atmosphere, but direct constraints on paleoatmospheric pressure P are lacking. Of particular interest is the climate that allowed rivers to flow early in Mars history, which was affected by P via direct and indirect greenhouse effects. The size of craters embedded within ancient layered sediments is a proxy for P: the smaller the minimum-sized craters that form, the thinner the past atmosphere. Here we use high-resolution orthophotos and Digital Terrain Models (DTMs) to identify ancient craters among the river deposits of Aeolis, and compare their sizes to models of atmospheric filtering of impactors by thicker atmospheres. The best fit is P <= 76070 mbar, rising to P <= 1640180 mbar if rimmed circular mesas are excluded. Surveys tend to undercount smaller craters, so these fits are upper limits. Our work assumes target properties appropriate for desert alluvium: if sediment developed bedrock-like rock-mass strength by early diagenesis, the upper limit is greatly increased. If Mars did not have a stable multibar atmosphere at the time that the rivers were flowing, the warm-wet CO2 greenhouse of Pollack et al. (1987) is ruled out, and long-term average temperatures were probably below freezing, implying that exoplanet habitable-zone calculations that use Mars as a reference point may need to be reconsidered.

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Remaining Martian Atmosphere Still Dynamic

Mars has lost much of its original atmosphere, but what's left remains quite active, recent findings from NASA's Mars rover Curiosity indicate. Rover team members reported diverse findings today at the European Geosciences Union 2013 General Assembly, in Vienna.
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Curiosity rover traces loss of Martian air

The degree to which Mars' atmosphere has thinned over time is evident in exquisite new measurements from Nasa's Curiosity rover.
It has analysed the different types, or isotopes, of argon atoms in the planet's air.
The study shows how a heavier version of the element has built up relative to a lighter one during Mars' history.

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NASA Rover Providing New Weather and Radiation Data About Mars

Observations of wind patterns and natural radiation patterns on Mars by NASA's Curiosity rover are helping scientists better understand the environment on the Red Planet's surface.
Researchers using the car-sized mobile laboratory have identified transient whirlwinds, mapped winds in relation to slopes, tracked daily and seasonal changes in air pressure, and linked rhythmic changes in radiation to daily atmospheric changes. The knowledge being gained about these processes helps scientists interpret evidence about environmental changes on Mars might have led to conditions favourable for life.

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