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Why does Mars methane vary in one Martian day? | space



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  A sophisticated wheel machine in a red-brown rocky landscape under a pale orange sky.

Self-portrait of Mars Rover Curiosity. Image via NASA / JPL-Caltech / MSSS / ANU.

The secret of Mars methane has reappeared in the news recently, starting with a study announced earlier this month that says it is likely that wind erosion is not caused by rocks. Now, a new new study has refined estimates of methane gas in the atmosphere of Mars, showing how concentrations change over a Martian day.

The published study, led by John Mours of York University in Canada, was published in Geophysical Research Letters on August 20, 201

9. According to Moores:

This new study redefines our understanding of how concentration is of methane in the atmosphere of Mars changes over time and this helps us to solve the greater mystery of what the source may be.

The source of Mars methane is a true mystery. Where did the methane come from? On Earth, methane gas can be linked to the life of germs. The idea of ​​living microbes on Mars has long been intriguing to astronomers. Various spacecraft sent to Mars are looking for signs of life, but so far no signs of life have been revealed. In 2018, scientists announced that seasonal variations in Mars methane could be related to microorganisms. Or methane deviations can be produced by geological means. This is an interesting puzzle!

The new study includes data from the orbit of Trace Gas (TGO) and the Curiosity Rover. Curiosity, at Gale Crater, has detected methane outbreaks in different periods in recent years, and analysis shows that it peaks in summer and disappears in winter.

Now, a new study shows that methane levels change over one Martian day. Moores notes:

This latest work suggests that the concentration of methane changes with each passing day. We were able – for the first time – to calculate a single figure for the methane penetration rate in Mars' Galle Crater, which is equivalent to an average of 2.8 kg [.7 gallons] on a Martian day.

  Graphic: low in late spring, high in summer-fall, again low in winter.

Diagram showing the seasonal cycle of methane as detected by the Curiosity Rover in Galle Crater. A new study shows that methane also varies in concentration daily. Image via NASA / JPL-Caltech / Mars Exploration Program.

From paper:

The Exome gas tracer and Curiosity Rover have recorded different amounts of methane in the atmosphere of Mars. The Trace Gas orbiter measures very little methane (<50 parts per trillion volumetric) over 5 km [3 miles] in the atmosphere of the sun, while Curiosity measures significantly more (410 parts per trillion volumetric) near the surface at night. In this document, we describe a framework that explains both measurements, assuming that a small amount of methane is leaking from the ground constantly. During the day, this small amount of methane is rapidly mixed and diluted by vigorous convection, which results in low overall levels in the atmosphere. At night, the convection decreases, allowing the methane to accumulate near the surface. At dawn the convection intensifies and the methane near the surface is mixed and diluted with much more atmosphere. Using this model and concentrations of methane from both approaches, we are able – for the first time – to put a single number of methane leakage rates in Galle Crater, which we find equivalent to 2.8 kg on a Martian day. A future spacecraft measuring methane near the surface of Mars can determine how much methane is leaking from the earth in different places, providing an idea of ​​what processes are creating that methane in the underground.

<img aria-describedby = "caption-attachment-319990" class = "wp-image-319990 size-large" src = "https://en.es-static.us/upl/2019/08/methane -plume-Mars-northern-summer-Jan-14-2009-800×450.jpg "alt =" Blue globe with large green areas with red centers. [19659017] Mars telescopic observations also showed methane concentrations peaking during the summer months. Image courtesy of NASA / Trent Schindler / Wikipedia

The findings should provide more clues as to the source of the methane, which may be biological or non-biological, at least for the methane discovered around Galle Crater. uriosity, which presented a puzzle While curiosity was detecting spikes in methane levels, TGO did not. As Moore explained:

We were able to resolve these differences by showing how methane concentrations were much lower in the atmosphere during the day. and significantly higher near the surface of the planet at night as the heat transfer decreases.

TGO focuses on analyzing upper levels of the atmosphere, which may explain why it missed methane eruptions near the ground, or perhaps because methane spikes are seasonal.

Seasonal and daily variations could be consistent with biology – as with germs – as a source of methane, but there are still other plausible geological explanations. According to Penny King of the Australian National University (ANU):

Some microbes on Earth can survive without oxygen, deep underground, and release methane as part of their waste. Mars methane has other possible sources, such as reactions on water rocks or decomposing materials containing methane.

  Diagram of underground surface characteristics, methane release from cracks in the ground.

Illustration depicting what processes can create and destroy methane. on Mars. Methane is likely to originate from below the surface and be discharged into the atmosphere through underground cracks. Image via ESA.

Although what creates methane is still unknown, most scientists now believe it originates from a dungeon and is periodically released through cracks. Again, this would be in line with either biology or geology. Geological sources can include interactions between water rocks or ice methane clathrates that contain methane and release it at warmer temperatures. If it were rock and water, it would still be an exciting find, showing that there is still liquid water underground and at least some residual active geological processes. This in itself could provide a pleasant habitat for germs, even if they do not produce methane by themselves. Whatever the explanation for methane, it will give a fascinating look at current geological or biological processes in red.

Bottom line: A new study shows how methane in the atmosphere of Mars varies in concentration on a daily basis, not just during the season.

Source: Daily variant of methane and microseason flow in Galle Crater, Mars, restricted by ExoMars Orbit and Curiosity Observations

Via ANU

  Paul Scott Anderson


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