Wednesday, 21 October 2015

The Martian Files: The Atmosphere

Mars in the present...
·         The composition of Mars’ atmosphere:
-        95,32%   CO2
-        2,7% Nitrogen
-        1,6% Argon
-        0,13% Oxygen
-        0,07% Carbon Monoxide
-        0,03% Water Vapour
-        Others: Neon, Krypton, Xenon, Ozone, Methane

·         Atmospheric pressure: it changes seasonally because the temperature is so cold that some carbon dioxide freezes during winter and snow down. In summer it rises up again. The atmosphere has a lot of dust in the atmosphere and the wind creates large storms.
·         Surface pressure is 0, 7% of the average surface pressure at sea level on Earth. Martian atmosphere raises the surface temperature 5*C in a week greenhouse effect. Water is usually frozen, but when temperature raise significantly, ice turns to vapour without becoming liquid.
·         In Mars there is methane and ammonia. This can mean that there is life in Mars.
Owing to methane is usually destroyed by sunlight in a few hundred years. But it*s still there, so the only explanation is that someone creates it.
Methane could be produced by volcanic eruptions, but there are no eruptions. Or it could be because of biological processes which say that magma carries out reactions with underground minerals producing methane. This occurs 10 km below the Martian surface, when water and rocks react to hydrogen, which combined with carbon or carbon dioxide produce methane.
Water + rock = H             H + C/CO2 = Methane
Ammonia can only survive a few hours, But it*s still in Mars. So something must produce it.
·         Water on Mars. When CO2 decomposes it forms C + O which mean that water vapour is present. And later it completes the cycle becoming CO2 again. In this process hydrogen molecules are created.
CO2 = C + O → C + O = CO2      H created.

Mars in the past...
Early in the 4.6-billion-year history of the solar system, the conditions on the Earth and Mars were almost certainly much more similar than they are now. On both planets the primitive atmosphere is thought to have originated in large part from gases, mainly water vapour, carbon dioxide, and nitrogen, vented from volcanoes. Evidence suggests that an ocean formed on Mars, covering, according to some estimates, one-third of the planet's surface to an average depth of 1,700m. Early on, large amounts of carbon dioxide in the Martian atmosphere probably led to a vigorous greenhouse effect which kept the average temperature above 0°C. This fact, together with the substantial atmospheric pressure, would have enabled surface water to remain as a liquid. On Mars the crust appears to consist of a single plate. Owing to its small size, Mars does not have enough internal heat to drive a significant level of tectonic and volcanic activity. Perhaps it did for a while when it was young. But after the Martian volcanoes fell silent no new carbon dioxide would have been pumped into the atmosphere, and that which was already there would have been gradually depleted. On Mars, large quantities of atmospheric carbon dioxide were probably taken up by liquid water on the surface and converted into carbonates. Ironically, therefore, the Martian ocean and rivers might well have been instrumental in their own demise for, as they removed more and more carbon dioxide, they would have brought about a lowering of the atmospheric pressure and a reduction in the greenhouse effect which had previously maintained the surface temperature above the freezing point of water.

Putting an accurate timescale on these dramatic changes in climate is not easy. For how long Mars was warm and wet? The original, volcanically-vented Martian atmosphere was probably in place around 4 billion years ago, toward the end of the period of heavy primeval bombardment. Judging by the structure of the valley systems and the extent to which some craters from the early bombardment phase have apparently been eroded by running water, a strong greenhouse effect must have persisted for about 500 million years. Even after this, however, some surface water presumably remained for a long time, continuing to remove carbon dioxide, in order that the atmosphere should have thinned out to its present extent. According to one estimate, the last dregs of the once great ocean on Mars disappeared some 3 billion years ago.

Mars experiences periodic ice ages but now are in the midst of a prolonged cold snap. There could be a number of reasons for this: variations in the tilt of the Martian rotation axis, fluctuations in the amount of solar energy. A gradual long-term reduction in the reflectivity of the poles could cause them to warm up and melt, releasing sufficient carbon dioxide to allow liquid water to exist again on the surface. Finally, it is conceivable that variations in the luminosity of the Sun have had their effect on Mars. Some of the channels, presumed once to have contained water, are pock-marked by occasional impact craters.

Mars in the future...
Michael Hecht will lead development of the MOXIE instrument that will fly on the Mars 2020 mission, which is one of the seven instruments that will accompany Mars 2020. This instrument is an MIT-led payload known as MOXIE, which will play a leading role in paving the way for human exploration.
The MOXIE instrument will attempt to make oxygen out of native resources in order to demonstrate that it could be done on a larger scale for future missions.
To do this, MOXIE will be designed and built as what Hecht calls a “fuel cell run in reverse.” In a normal fuel cell, fuel is heated together with an oxidizer — often oxygen — producing electricity. In this case, however, electricity produced by a separate machine would be combined with carbon dioxide from the Martian air to produce oxygen and carbon monoxide in a process called solid oxide electrolysis.
For people to return safely they need a rocket to lift off the planet.. So if we can eliminate that piece by making the oxygen on Mars, we’re way ahead of the game.”

First, a small nuclear reactor would be sent to the Red Planet along with a scaled-up version of the MOXIE instrument. Over a couple of years, its oxygen tank would fill up in preparation for human visitors. Once the crew arrives, “they have their power source, they have their fuel, and the infrastructure for the mission is already in place,” Hecht says. “That’s the piece we’re after.”

Producing oxygen on the Martian surface would eliminate the difficulty and expense of sending liquid oxygen stores to Mars.
We’ve never run a factory on Mars. But this is what we’re doing; we’re running a prototype factory to see what problems we might come up against.

Oxygen can also be produced by splitting water into its constituent parts, hydrogen and oxygen. The oxygen will be used to provide a breathable atmosphere and a portion will be stored for conditions, for example at night, and during dust storms.

By Amy G., Raquel A., Gema G. and Anastasiya M.

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