Liquid water on Mars
A study conducted by researchers at the Mars Group at the University of Copenhagen shows that water can exist in liquid near the Martian surface. The discovery has been obtained thanks to the discovery of perchlorate in the soil calcium, a substance which allows keeping the water in the liquid state, in the form of frost salt.
It is known for some time that Mars contains water in the form of ice. Today, however, new data obtained from the Curiosity rover NASA show that the water can exist in the liquid state in the vicinity of the surface of Mars. The explanation comes from the finding in the soil of perchlorate calcium, an inorganic compound and a strong oxidizing agent, which lowers the freezing point for which the water becomes ice but remains liquid and present in the form of frost, very salty. The results are published in Nature.
Credit: Javier Martin-Torres et al.
In August 2012, the rover Curiosity landed near the region of the great Lake Gale, located south of the equator of Mars. The crater has a diameter of 154 km and in its center stands a peak of 5 Km, known as Mount Sharp. During two and a half years, Curiosity has traveled to more than 10 Km heading towards Mount Sharp and conducting a series of studies of the Martian soil.
“We found traces of perchlorate in the soil of football, if there are the right weather conditions, is able to absorb vapor from the atmosphere,” says Morten Bo Madsen, head of the Mars Group at the Niels Bohr Institute, University of Copenhagen and co-author of the study. “Our measurements from weather station rover show that these favorable conditions you have at night and just after dawn in winter. Based on measurements of the gradient of temperature and humidity relative to a height of 1.6 meters above the surface of the planet, we are able to estimate the amount of water that is absorbed. When the night comes, part of the water vapor present in the atmosphere condenses on the surface of the planet Mars in the form of frost, but because the calcium perchlorate has a high degree of absorption it frost forms, therefore, the freezing point is lowered and the frost that had formed turns into liquid water.
Credit: NASA/JPL, MSSS
The soil is porous, so what we see is the water that seeps through the soil. In the course of time, may be dissolved in the ground other salts that being in the liquid state can flow somewhere else falling below the surface. ”
Initially, the images taken with the camera stereo Curiosity showed us areas characteristics of old river channels where there are rounded pebbles that represent clear evidence of the fact that long ago there had to be some real rivers with a depth up to about one meter. Now, the new close-up images taken by the rover along its journey towards Mount Sharp show that there are real expanses of sedimentary deposits that lie as the “plaques” one above the other, slightly sloping towards Mount Sharp.
“We believe that these sedimentary deposits were formed when huge flows of water have spread along the walls of the crater, flowing towards the stagnant water in the lake. When the current meets the surface, the solid material that is transported by water drops rolls and it is deposited on the shore of the lake. Gradually, it forms a slightly inclined slope just below the surface of the water where they were found traces of these deposits during the journey that carried the rover to Mount Sharp. In addition, other sediments much finer, which are precipitated slowly thanks to the currents of water, have accumulated exactly in the deepest part of the crater. Here the plates are sedimentary leveled so this suggests that the entire Gale Crater may have been at one time a very large lake, “says Morten Bo Madsen.
Another study by researchers at NASA has allowed us to realize a number of unique maps of the distribution of atmospheric water Martian, suggesting that about 4.5 billion years ago, Mars was to hold a quantity of water at least 6.5 times greater than the current one and a very thick. But most of the water has disappeared, evaporating in the space, because of the absence on the red planet a global magnetic field, which is present instead on Earth.
The currents due to the motions of the liquid iron distribution in the inner layers of the Earth’s core generate the magnetic field that acts as a sort of shield protecting the Earth from cosmic radiation. In addition, the Earth’s magnetic field protects the atmosphere of our planet from the energetic particles that make up the solar wind. Mars no longer has a magnetic field, so the atmosphere is not protected from solar radiation. In this way, the charged particles (typically protons) of the solar wind slowly dissolve the Martian atmosphere that ends in outer space.
In short, even if you have to find clear evidence of the presence of liquid water, it does not mean that you will find life forms on Mars Elementary. The red planet is too dry, too cold and cosmic radiation is so powerful that it penetrates at least up to about a meter inside the planet’s surface, thus destroying any possible form of life, at least as we know it here on Earth.