text: The red planet might still have liquid water, suggests information collected by Nasa's Curiosity rover. Researchers have long known that there is water in the form of ice on Mars. Now, new information from the Mars rover Curiosity, published in the journal Nature, shows that it is possible that there is liquid water close to the surface of the red planet. The ‘Hidden Valley’ in Gale Crater on Mars. Very fine-grained sediments, which slowly fell down through the water, were deposited right at the bottom of the crater lake. The sediment plates at the bottom are level, so everything indicates that the entire Gale Crater may have been a large lake. New information from Nasa's Mars rover Curiosity, published in the journal Nature, shows that it is possible that there is liquid water close to the surface of the red planet. The explanation is that the substance perchlorate has been found in the soil, which lowers the freezing point so the water does not freeze into ice, but is liquid and present in very salty water. Curiosity detected salts called perchlorates, which can absorb water from the atmosphere and turn it into briny liquid. When night falls, some of the water vapour in the atmosphere condenses on the planet surface as frost, but calcium perchlorate is very absorbent and it forms a brine with the water, so the freezing point is lowered and the frost can turn into a liquid. Curiosity landed on Mars in 2012 in the large crater, Gale, located just south of the equator. The giant crater is 154 kilometres in diameter and the rim of the crater is almost five kilometres high. In the middle of the crater lies the mountain, Mount Sharp. Curiosity has travelled more than 10km from the landing site towards Mount Sharp and has carried out many studies along the way. Doctor Morten Bo Madsen, associate professor and head of the Mars Group at the Niels Bohr Institute at the University of Copenhagen in Denmark, said: 'We have discovered the substance calcium perchlorate in the soil and, under the right conditions, it absorbs water vapour from the atmosphere. 'Our measurements from the Curiosity rover's weather monitoring station show that these conditions exist at night and just after sunrise in the winter. 'Based on measurements of humidity and the temperature at a height of 1.6 metres and at the surface of the planet, we can estimate the amount of water that is absorbed. 'When night falls, some of the water vapour in the atmosphere condenses on the planet surface as frost, but calcium perchlorate is very absorbent and it forms a brine with the water, so the freezing point is lowered and the frost can turn into a liquid. Researchers say that Gale Crater was once a giant lake on the red planet . 'The soil is porous, so what we are seeing is that the water seeps down through the soil. 'Over time, other salts may also dissolve in the soil and now that they are liquid, they can move and precipitate elsewhere under the surface.' Observations by the Mars probe's stereo camera have previously shown areas characteristic of old riverbed with rounded pepples that clearly show that a long time ago there was flowing, running water with a depth of up to one metre. Now the new close-up images taken by the rover all the way en route to Mount Sharp show that there are expanses of sedimentary deposits, lying as 'plates' one above the other and leaning a bit toward Mount Sharp. Evidence of water on Mars dates back to the Mariner 9 mission, which arrived in 1971. It revealed clues of water erosion in river beds and canyons as well as weather fronts and fogs. Viking orbiters that followed caused a revolution in our ideas about water on Mars by showing how floods broke through dams and carved deep valleys. Mars is currently in the middle of an ice age, and before this study, scientists believed liquid water could not exist on its surface. In June 2013, Curiosity found powerful evidence that water good enough to drink once flowed on Mars. In September of the same year, the first scoop of soil analysed by Curiosity revealed that fine materials on the surface of the planet contain two per cent water by weight. Last month, scientists provided the best estimates for water on Mars, claiming it once had more liquid H2) than the Arctic Ocean - and the planet kept these oceans for more than 1.5 billion years. The findings suggest there was ample time and water for life on Mars to thrive, but over the last 3.7 billion years the red planet has lost 87 per cent of its water - leaving it barren and dry. Dr Madsen said: 'These kind of deposits are formed when large amounts of water flow down the slopes of the crater and these streams of water meet the stagnant water in the form of a lake.' However, he added that it is not likely that life will be found on Mars as it is too dry, too cold and the cosmic radiation is so powerful that it penetrates at least one metre into the surface and kills all life - at least life as we know it on Earth. The finding, however, could make it easier for humans to live on Mars in the future. He explains that about 4.5 billion years ago, Mars had 6.5 times as much water as it does now and a thicker atmosphere. But most of this water has disappeared out into space and the reason is that Mars no longer has global magnetic fields, which we have on Earth. Observations by the Mars probe's stereo camera have previously shown areas characteristic of old riverbed with rounded pepples that clearly show that a long time ago there was flowing, running water with a depth of up to one metre. Currents of liquid iron in the Earth’s interior generate the magnetic fields and they act as a shield that protects us from cosmic radiation. The magnetic field protects the Earth’s atmosphere against degradation from energy rich particles from the sun. But Mars no longer has a global magnetic field and this means that the atmosphere is not protected from radiation from the sun, so the solar particles (protons) simply ‘shoot’ the atmosphere out into space little by little.
target: Possible that there is liquid water close to the surface of the red planet .
  Substance perchlorate has been found in the soil, which lowers the freezing point so the water does not freeze into ice, but is liquid .
  Life as we know it is 'not likely' to exist due to planet's harsh conditions .
  Finding could make it easier for humans to live on Mars in the future.