Researchers Have Found A Giant Lake Of Liquid Water On Mars

For decades we've searched for water on Mars, and we have found very little, either in the form of trickles on the surface or frozen as ice. However, an incredible discovery might change everything.

As recently stated in the journal Science, researchers led by Dr. Roberto Orosei from the National Institute of Astrophysics (INAF) in Rome claim they've found a vast reservoir of water beneath the south pole of Mars. It is so vast that it looks similar to a something like a subglacial lake on the Earth – one where life could actually arise.

“This is potentially the first habitat we know of on Mars,” Dr. Orosei told IFLScience. “It’s the first place where microorganisms like those that exist today on Earth could survive.”

A radar instrument discovered the large reservoir of water, the Mars Advanced Radar for Subsurface as well as Ionosphere Sounding (MARSIS) instrument, on board ESA’s Mars Express spacecraft. The team also used data collected by the spacecraft from May 2012 to December 2015.

The data demonstrated that 1.5 kilometers (0.9 miles) below the surface, in an area called Planum Australe, there was a definite source of liquid water spanning about 20 kilometers (12 miles) across. The team doesn't know how deep this reservoir of water is. However, they note it's at least deeper than a few tens of centimeters, and perhaps more.

The lake was found using radar pulses from the Mars Express spacecraft. USGS/ASU/ESA/INAF/Davide Coero Borga

The radar signal detected by the spacecraft. The water is shown in blue. ESA/INAF/Davide Coero Bora

It was detected by sending 29 sets of radar pulses under the surface, with reflections demonstrating a radar signal practical identical to that from lakes of liquid water discovered beneath the ice of Antarctica and Greenland on Earth, heavily suggesting it's liquid water. Nevertheless, the exact nature of the water at the moment is unclear.

“It’s very difficult to say what we’re really looking at,” Dr. Anja Diez from the Norwegian Polar Institute in Tromsø, Norway, who wrote an accompanying perspective on the research, told IFLScience. “It could either be a thin layer of water, a large layer, or water in sediments.”

The team said that they considered some other possibilities for the signal, such as a layer of carbon dioxide ice or very low-temperature water ice. However, they suggest that these are unlikely as they wouldn't have caused as a strong a reflection as viewed in the data.

The characteristics of the suspected water are complicated by the conditions it is in. On Earth, subglacial lakes reach temperatures of approximately -60°C (-76°F). Nevertheless, the intense pressure of the ice above lowers the melting point of the water, to the point where it exists as a liquid in large freshwater lakes.

However, in this region on Mars, it is thought the temperatures drop to approximately -68°C (-90°F). For the water to remain liquid there, it is likely full of salts like magnesium, calcium, and sodium and thus briny, rather than like the freshwater lakes discovered under the ice on Earth. We do have some briny lakes on Earth, however.

A handful of subglacial lakes have been drilled into on Earth, including Lake Vostok in Antarctica. These projects aren't easy, and it can take years to dig below several kilometers of ice. However, the scientific payoff is enormous – and every time we drill down, we discover life.

Previously on Mars, we've discovered evidence for water trickling on the surface, known as recurring slope lineae (RSL). Those features are short-lived, though, with the water quickly evaporating in the low-pressure environment on the Martian surface.

It has long been theorized, however, that there might be more stable bodies of liquid beneath the surface, as evidenced in this research. And if this is the case, it provides an amazing new habitat for microorganisms of the past or present on Mars.

“It’s very important to know if this [reservoir] is a unique thing,” said Dr. Orosei. “If it’s regional, not local, then you can have a whole system of subglacial lakes similar to what you see on Earth. You would have ways for living organisms, if they existed, to have a much larger environment and perhaps move around.”

To answer this, the team hopes to use more data from Mars Express over the coming years. The spacecraft is aging, however, and it is running out of fuel, so time is of the essence.

RSL on Mars (seen lower left here on the Krupac Crater) is our best previous evidence of water. NASA/JPL-Caltech/Univ. of Arizona

Getting to these sources of liquid water in the future might also be difficult. Drilling operations on Earth require complicated machinery, something we do not have on Mars. The upcoming European ExoMars rover in 2020 will be able to drill about 2 meters (6.6 feet) below the surface, but that might not be enough to get close to subsurface reservoirs of water like this.

There are still unanswered questions concerning this liquid water discovery. It is not clear if it is a large body, or just water seeping in between rocks. What it does suggest, however, is that liquid water exists beneath the surface of Mars.

On Earth, liquid water almost always means life. Coupled with the recent discovery of the building blocks of life on Mars, and the possibility it once had a more habitable environment, the evidence is building that the Red Planet might not be so dead after all.

“It’s likely that this is what we would describe as a habitat,” said Dr. Orosei. “It has at least some of the conditions that terrestrial microorganisms would need to survive.”

Reference: IFLScience