Recent badlands on Mars suggest that water could flow to the planet again in the future

The gully-like channels on Mars are something of a conundrum. They look like Antarctica’s gullies caused by melting glaciers, but the elevated positions of many of the features aren’t places we’d expect to find recently flowing water.

So how did these gorges on Mars form? Sublimation of carbon dioxide ice has been proposed as an alternative hypothesis, but a new study by a team of scientists in the US suggests that under the right conditions, liquid water could indeed do the job. Furthermore, it could have happened as recently as geological timescales, perhaps as recently as 630,000 years ago.

The key is the tilt of the planet’s axis. When the tilt reaches 35 degrees, the new temperature and circulation simulation shows, the density of the atmosphere would cause the surface to briefly warm above the freezing point. That would be enough to melt some of the snow and ice that is still on Mars.

“We know from a lot of our research and that of other people that early in Mars’ history there was flowing water on the surface with networks of valleys and lakes,” he says Brown University planetary scientist Jim Head.

“But about 3 billion years ago, all that liquid water was lost and Mars became what we call a hyper-arid or polar desert.”

The calculations performed by the research team shed light on how these gullies start, how much erosion they cause and how far they can extend. The team was able to fit their model to data from the Terra Sirenum region of Mars, comparing it to times when gullies are thought to have expanded rapidly in the area.

A double gorge formation scenario, where the channels created by melting ice are then further eroded by CO evaporation2 frost. These locations most likely still have ice reserves trapped beneath the surface and would have had many more in the past.

Flowing water erosion fits the features of the Martian landscape better than CO2-related to erosion, which has no equivalent on Earth that we can study, and tends not to cause the same effects on the rock it comes into contact with. This type of activity has been observed on modern Mars through high-resolution satellite imagery.

Mars inclination diagram
When Mars tilts, its atmosphere changes. (Dickson et al., Science2023)

“Our study shows that the global distribution of badlands is best explained by liquid water over the past million years,” says planetary scientist Jay Dickson, of the California Institute of Technology.

“Water explains the elevation distribution of gullies in ways that CO2 He can not. This means that Mars has been able to create liquid water in sufficient volume to erode the channels over the past million years, which is very recent on the scale of Mars’ geological history.”

The tilt of Mars’ axis is known to change over time, even if it takes hundreds of thousands of years. This movement has previously been linked to ice ages on the red planet.

Running meltwater on Mars in the relatively recent past would have made it easier for organisms to develop, so the research also offers an interesting new perspective on the potential for life on Mars.

Eventually, the planet will revert to a 35-degree angle, allowing localized patches of liquid water to flow once more.

To bring it all the way back to Antarctica’s Dry Valleys, life remains in a sort of stasis when liquid water is unavailable. It is not excluded that something similar could also happen on Mars.

“Could there be a bridge, if you will, between early warm and humid Mars and the Mars we see today in terms of liquid water?” says Chief. “Everyone is always looking for environments that can favor not only the formation of life, but also its conservation and continuation”.

“Any microorganisms that may have evolved on early Mars will be in places where they can do well in ice and then also do well or thrive in liquid water.”

The research was published in Science.

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