Methane deposits may have once allowed liquid water to flow on Mars
Researchers have found that methane deposits may have allowed Mars to maintain liquid water on its surface.

By Jackie Flores | Jul 28, 2017

Ancient methane eruptions could help explain how Mars once maintained liquid water on its surface despite its cold, arid climate.

Over the past 10 years, researchers have discovered a plethora of evidence that suggests water once flowed freely across the Red Planet. In fact, many signs show water existed on Mars as recently as 3 billion years ago. However, that finding is strange because many studies have also shown Mars had a cold, dry climate during that time.

Though many astronomers have studied Mars' past, nobody been able to explain that contradiction.

"It's a paradox, an unresolved paradox of Mars," Kevin Zahnle, a NASA scientist who was not involved in theresearch,told The Verge. "On the one hand, some people say that it looked warmish and wettish, at least occasionally. On another hand, nobody can figure out how it could have been warmish and wettish."

Around 3 billion years ago, Mars' Hesperian period -- when the climate shifted from cold and wet to cold and dry -- came to an end. By that time, the planet's water should have been frozen into ice. However, 3.5-billion-year-old lake beds found on the rocky surface show that is not true.

To explain the discrepancy, scientists estimate that ages of unusual warming caused by outflows of methane took place during the Hesperian period. Such stretches would have warmed the planet and melted the ice, creating large areas of water.

Methane ice is a volatile substance. As a result, researchers think that when Mars tilted on its axis and pointed methane deposits towards the sun it pushed large quantities of the substance out into the atmosphere. This then caused periods of global warming that melted down water ice all across the planet's surface.

This is a compelling study, but there are still many questions that need to be answered before any conclusions can be made. For instance, while the tilting likely played a role in the process, the team found the shift was not enough to cause true warming. Rather, Mars' atmosphere would have had to feature a significant amount of carbon dioxide as well. Though scientists have tried to find signs of heightened CO2 levels in Mars' rocks, they have come up empty so far.

"Having a thick CO2-rich atmosphere leads to some expectations about the kinds of rocks you would find deposited at that time," explained Thomas Bristow, a researcher at NASA's Ames Research Center, according to UPI. "You would expect to see lots of carbonate minerals around, particularly in sedimentary rocks, but we don't see them."

Another problem is that, as the study is only based on computer models, researchers do not have any direct evidence of methane deposits on Mars. Even so, the team believes there is credence to their new theory and that further research could help explain one of the Red Planet's biggest mysteries.

The new study is published in the journal Nature Geoscience.

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