First evidence of planet-wide groundwater system on Mars

**First evidence of planet-wide groundwater system on Mars
Example of features identified in a deep basin on Mars that show it was influenced by groundwater billions of years ago. Credit: NASA/JPL-Caltech/MSSS

Mars Express has revealed the first geological evidence of a system of ancient interconnected lakes that once lay deep beneath the Red Planet's surface, five of which may contain minerals crucial to life.

Mars appears to be an arid world, but its surface shows compelling signs that large amounts of once existed across the planet. We see features that would have needed water to form – branching flow channels and valleys, for example – and just last year Mars Express detected a pool of beneath the planet's south pole.

A new study now reveals the extent of underground water on ancient Mars that was previously only predicted by models.

"Early Mars was a watery world, but as the planet's climate changed this water retreated below the surface to form pools and 'groundwater'," says lead author Francesco Salese of Utrecht University, the Netherlands.

"We traced this water in our study, as its scale and role is a matter of debate, and we found the first geological evidence of a planet-wide groundwater system on Mars."

Salese and colleagues explored 24 deep, enclosed craters in the northern hemisphere of Mars, with floors lying roughly 4000 m below martian 'sea level' (a level that, given the planet's lack of seas, is arbitrarily defined on Mars based on elevation and atmospheric pressure).

**First evidence of planet-wide groundwater system on Mars
This image shows the distribution of a number of deep craters (marked as dots) recently explored as part of a study into groundwater on Mars.The background image is shown in colours representing topography: reds and oranges are lower elevations, and blues and greens are higher ones. The study found that the floors of the basins, which sit over 4000 m deep, show signs of past water – the first geological evidence that the Red Planet once had a system of interconnected groundwater-fed lakes that spanned the entire planet. Credit: Topography: NASA/MGS/MOLA; Crater distribution: F. Salese et al (2019)

They found features on the floors of these craters that could only have formed in the presence of water. Many craters contain multiple features, all at depths of 4000 to 4500 m – indicating that these craters once contained pools and flows of water that changed and receded over time.

Features include channels etched into crater walls, valleys carved out by sapping groundwater, dark, curved deltas thought to have formed as water levels rose and fell, ridged terraces within crater walls formed by standing water, and fan-shaped deposits of sediment associated with flowing water.

The water level aligns with the proposed shorelines of a putative martian ocean thought to have existed on Mars between three and four billion years ago.

"We think that this ocean may have connected to a system of underground lakes that spread across the entire planet," adds co-author Gian Gabriele Ori, director of the Università D'Annunzio's International Research School of Planetary Sciences, Italy.

"These lakes would have existed around 3.5 billion years ago, so may have been contemporaries of a martian ocean."

**First evidence of planet-wide groundwater system on Mars
This diagram shows a model of how crater basins on Mars evolved over time and how they once held water. This model forms the basis of a new study into groundwater on Mars, which found that a number of deep basins – with floors sitting over 4000 m deep – show signs of having once contained pools of water. Images (from the context camera onboard NASA’s Mars Reconnaissance Orbiter) show examples of the different features observed in the basins. There are three main stages: in the first (top), the crater basin is flooded with water and water-related features – deltas, sapping valleys, channels, shorelines, and so on – form within. In the second stage (middle), the planet-wide water level drops and new landforms emerge as a result. In the final stage (bottom), the crater dries out and becomes eroded, and features formed over the previous few billions of years are revealed. Credit: Images: NASA/JPL-Caltech/MSSS; Diagram adapted from F. Salese et al. (2019)

The history of water on Mars is a complex one, and is intricately linked to understanding whether or not life ever arose there – and, if so, where, when, and how it did so.

The team also spotted signs of minerals within five of the craters that are linked to the emergence of life on Earth: various clays, carbonates, and silicates. The finding adds weight to the idea that these basins on Mars may once have had the ingredients to host life. Moreover, they were the only basins deep enough to intersect with the water-saturated part of Mars' crust for long periods of time, with evidence perhaps still buried in the sediments today.

Exploring sites like these may thus reveal the conditions suitable for past life, and are therefore highly relevant to astrobiological missions such as ExoMars – a joint ESA and Roscosmos endeavour. While the ExoMars Trace Gas Orbiter is already studying Mars from above, the next mission will launch next year. It comprises a rover – recently named after Rosalind Franklin – and a surface science platform, and will target and explore martian sites thought to be key in the hunt for signs of life on Mars.

"Findings like this are hugely important; they help us to identify the regions of Mars that are the most promising for finding signs of past life," says Dmitri Titov, ESA's Mars Express project scientist.

"It is especially exciting that a mission that has been so fruitful at the Red Planet, Mars Express, is now instrumental in helping such as ExoMars explore the planet in a different way. It's a great example of missions working together with great success."

Mars Express was launched on 2 June 2003, and reached 15 years in space last year. This study used observations from the High Resolution Stereo Camera (HRSC) on ESA's Mars Express, from NASA's High Resolution Imaging Science Experiment (HiRISE), and from the Context Camera aboard NASA's Mars Reconnaissance Orbiter. A digital terrain model was used based on data from the HRSC and NASA's Mars Orbiter Laser Altimeter.

Explore further

Signs of ancient flowing water on Mars

More information: Francesco Salese et al. Geological Evidence of Planet-Wide Groundwater System on Mars, Journal of Geophysical Research: Planets (2019). DOI: 10.1029/2018JE005802
Citation: First evidence of planet-wide groundwater system on Mars (2019, March 1) retrieved 17 October 2019 from
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Mar 01, 2019
This website has nothing but fake science!

Mar 01, 2019
You mean "not jebus."

Which is stupid.

Mar 01, 2019
You mean "not jebus."

Which is stupid.

rodkeh might be looking for woo, though. Aliens, and the like. Or the other sorts of woo that we see entirely too much of around here.

Mar 01, 2019
I just wanna know what his version of "fake science" is...
Real science is often pretty boring and tedious, so it takes a lot of imagination to make it seem exciting...

Mar 01, 2019
Mars might be nice, but to preserve our heritage we need to look far beyond this solar system. Also going back down in another gravity well after escaping the one we live in is a bad idea.

Mar 02, 2019
The place is a dry and dead as parts of Afghanistan after a carpet bombing.

Mar 02, 2019
Not unexpected, but an unexpected hard-to-do find. Interesting that the ocean and the groundwater timing agree on a global water saturated (well) world 3.5 Gyrs back, which then should have had Earth equivalent atmosphere pressures to support rain and suppress evaporation.

but to preserve our heritage we need to look far beyond this solar system.

Depend on your time scale and sense of heritage, we don't know that we can do interstellar travel, and even if we did our species will live a million years due to evolution. If it is just leaving a heritage we can as well do it here, and if other language capable species will later evolve (say, our immediate descendants) they can have it.

The place is a dry and dead [unnecessary obliging of violence]

Irrelevant and irrelevant, if the premise is to learn more about Mars and possible extant or extinct life there.

Mar 02, 2019
Woo Hoo! rodkeh,babydoll! Since the Science is fakery?
That logical conclusion is that Based on fake Science, the technology must also be fake!

& as long as we are following you down the looneytoon trail?
Which brand of Ouija Board are you using to communicate with the rest of us?
Does it have one of those super-duper Aetherplasmatroid EU-SSU Model chips from the Crypto Jeebus & Bunco Conglomeoverrated?

WhyGy, I just gotta insert my two pfennings.
Science is Fun!
Go ahead laugh,
I can see your lips quivering as you try to keep a straight face.
I'll keep poking healthy-humor at your funny-bone until you guffaw.

torbjorn, my take from this article? Before looking up the original research reports.

A whole lot of conjectures.
Probabilities based on assumptions about an ancient Mars Hydrosphere.
At least the researchers were smart enough to hedge their bets considering the difficulty of getting accurate data at such a distance.

Mar 03, 2019
Excellent news! There is a high probability that there exists groundwater in considerable quantity in some regions. A low-frequency soil moisture mission would definitely help.

Mar 03, 2019
guptm, you might want to read the orinating research paapers before celebrating water on Mars, today.

My reading leads me to the conclusion that this research was determining where, long, very long ago, water may have surfaced on Mars.

Then speculating a vague possibility that there maybe today, mineral formations containing water.

That would need major industrial with expensive energy requirements to process the minerals into potable water.

I still suggest for potential Luna & Mars explorers.
Collect a few orbiting icebergs. Send those ahead to orbit your chosen destination.
When you arrive & analyze all the data from preceding swarms of robot prospectors?

Once you have determined an optimal landing site back down into yet another confining gravity well?

Drop a few of the icebergs right where those could actually be useful immediately producing potable water at minimal effort & expense.

Mar 04, 2019
Probabilities based on assumptions about an ancient Mars Hydrosphere.
At least the researchers were smart enough to hedge their bets considering the difficulty of getting accurate data at such a distance.

Mar 16, 2019
The water is still there. It is now ice, covered with eons of blown dust. Water is just like another mineral except it supports LIFE. That water will support US too if we go there.

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