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New ones arrive confirmations the presence of liquid water on Mars. The first discovery of liquid water on the red planet dates back to July 2018when a team of Italian researchers identified the presence of a lake of water under the south polar cap Martian. The existence of this basin has been questioned by some studies published last year, but a recent study published in Nature Astronomy showed new data united with computer simulations in support of the initial hypothesis. And there’s more: it seems to be under the ice of the Martian South Pole not a single lake, but four different lakes.
Let’s see the history of this extraordinary discovery together.
The initial discovery
Mars is a cold, desert and completely uninhabitable planet. But that wasn’t always the case: approx three billion years ago it was a hospitable world, with comfortable temperatures, a dense atmosphere and, above all, liquid water in abundance.
We don’t know exactly what the planet made it unsuitable for life we know today, but we know for sure that at some point in its history its oceans, seas, lakes and rivers are completely evaporatedno longer leaving a drop of water on its surface.
However, this does not mean that the red planet is completely dry. In the underground Martian water may have been preserved for all this time. In 2018, the European probe Mars Express he discovered for the first time, thanks to his radar MARSIS (Mars Advanced Radar for Subsurface and Ionosphere Sounding) made in Italya liquid water deposit a 1.5 km deep under the ice sheet that occupies the south pole of Mars.
MARSIS is able to measure the reflectivity of the materials, from which theirs can be traced density. Thus liquid water can be distinguished from solid water. It is precisely in this way that basins of liquid water were discovered under the Earth’s polar caps. After discarding all other hypotheses, the team – all Italian – of MARSIS had concluded that there were at least 10 billion liters of water at a temperature of approx –68 ° C.
How does water be liquid at those temperatures? Well, we all know the salt lowers the freezing temperature of the water. The only way to have liquid water at –68 ° C is to have one dissolved in that water large amount of salts.
The new evidence of the presence of liquid water
To resolve this, the original discovery team looked at the laser altimeter data GRINDSTONE mounted on the probe Mars Global Surveyor (no longer operational) to measure the topography of the south polar cap in the area (about 20 km wide) where the lake is believed to exist. Well, the data clearly shows some elevation anomalies: the area has some undulations quite similar to those found in the ice that dominates the terrestrial subglacial lakes.
The data from MOLA and those from MARSIS were then compared with the forecasts of sophisticated computerized models developed atCambridge University that simulate the behavior of a subglacial lake under Martian conditions. The model also took into account a variable flow of geothermal heat coming from within the planet.
The results of the simulations match the observational data very well. Explaining what MARSIS and MOLA found without invoking the presence of liquid water is now much more difficult.
The possible consequences for Martian geology
The study indicates the possible presence of three other deposits from liquid water in the immediate vicinity of the lake discovered in 2018. This means that the presence of subglacial liquid water may not be a very rare and unlikely situation, but on the contrary it could be a widespread phenomenon. And this is where geothermal heat comes into play.
According to the simulations, the age of altimetric anomalies on Martian ice depends significantly on the flow of geothermal heat coming from the Martian subsoil: 0.5-1.5 million years if the flow is high, 2-5 million years otherwise. In other words, such heat could come from a ‘magmatic activity recently occurred in the Martian past! All of this of course could have a significant impact in our knowledge of Martian geology and will certainly be investigated in more detail in the future.
Is there life there?
The first thing you think about when it comes to liquid water on another planet is possible presence of life. Here, however, two aspects that are far from negligible must be taken into account:
- The water we are talking about has one very low temperaturelower than even the most cold-weather-equipped organisms here on Earth can handle.
- To remain liquid, this water has extremely high salinity levelsprobably more than is tolerable for a terrestrial organism.
It means that the chances of something alive swimming down there, even a single-celled microorganism, are incredibly low, unless you want to imagine some kind of incredibly resilient extremophile organism. Unfortunately, we won’t be able to recover that water, at least until we learn how to drill 1.5km on another planet. Which certainly won’t happen for a long time to come.
