Back in 2018, researchers announced an amazing discovery - they found a lake on Mars! And not some modest reservoir, but a 20-kilometer lake of liquid water, hidden at a depth of 1.5 km under the south polar cap.
Of course, this is amazing news. But how did this lake manage to maintain a fluid state? Initially it was believed that it contained special impurities of salt and the influence of pressure from the glacier, which allows the water not to freeze, although its temperature should still be subzero.
Scientists have considered many other options. However, the latest study points to the role of the volcanic activity of the Red Planet. It is believed that only the presence under the surface of the pool with magma will allow to create enough heat to keep the lake liquid under the ice massif.
The artistic vision of the Mars Express spacecraft in orbit with radar data on the left. The blue spot marks the presence of subsurface liquid water.
Why option with impurities (salt) is not suitable? The fact is that the solutions will not be able to answer for the liquid of the lake, since the temperature under the ice layer is too cold and is -68 ° C. One of the new models showed a curious scenario.
If somewhere 300,000 years ago, volcanic activity released magma into a cavity with a width of at least 5 km, located 10 km below the lake's location, then this magma could generate the necessary heat to melt the ice to melt. If the lake does not have salt impurities, then the igneous chamber should be closer to the surface. It turns out that the scheme looks like this: a glacier - a lake (1.5 km below) - a pool with magma (10 km below the lake).
The artistic image of the Mars Express spacecraft over the territory of the Southern Plateau with data from the field of study superimposed on the surface of the Red Planet.
The idea of having a magma chamber has important implications for Mars exploration. It turns out that the Red Planet became geologically active much later than previously thought. Recent findings indicated activity millions of years ago.
This model also adversely affects the possible inhabitants of the lake. Scientists hoped to find life in liquid salt water. But if the lake was formed several hundred thousand years ago, then life would not have time to appear.
For now, these are all guesses and assumptions that can be verified on the spot with the help of future robotic missions or human studies.