New measurements of Martian climate and soil conditions suggest the soil is moist with liquid brine, which can stay liquid when temperatures drop below freezing. The result opposes theories that it’s too dry and cold for water on the Red Planet. The measurements, founded on a full year’s study of the planet’s temperature and moistness by NASA’s Curiosity rover, specify that surroundings at the Gale Crater are “promising for small quantities of brine to form.” The brine is formed when the salt perchlorate absorbs water vapor from the atmosphere and then depresses the freezing point of water. When mixed with calcium perchlorate, liquid water can exist down to around -70 Celsius. Report’s author, Javier Martin-Torres of the Spanish Research Council, said in a statement “Liquid water is a requirement for life as we know it, and a target for Mars exploration missions. Conditions near the surface of present-day Mars are hardly favorable for microbial life as we know it, but the possibility for liquid brines on Mars has wider implications for habitability and geological water-related processes.”
The new measurements propose that until just after dawn during winter nights, temperatures and humidity levels are just favorable for brine to form. Curiosity first identified the salt perchlorate in 2008 but the weather data readings assisted researchers understand that conditions would be high enough to form brine. NASA said that when relative humidity gets above a threshold level, salts can absorb plentiful water molecules to become dissolved in liquid. Marten Bo Madsen, a high-ranking Mars scientist at the University of Copenhagen, told the Guardian “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,” The weather data, issued under the heading “Transient liquid water and water activity at Gale Crater on Mars,” was issuedon Monday on Nature.com.
Co-author of the study, Alfred McEwen, principal investigator of High Resolution Imaging Science Experiment at the University of Arizona, Tucson, said in a statement “Gale Crater is one of the least likely places on Mars to have conditions for brines to form, compared to sites at higher latitudes or with more shading. So if brines can exist there, that strengthens the case they could form and persist even longer at many other locations,” said.
The Gale Crater is situated just south of Mars’ equator and is 154 kilometers in diameter, with the edge almost five meters high. In the middle of the crater is Mount Sharp, which Curiosity is mounting. Even with this finding, however, life on Mars is doubtful. Scientists say if life existed, it vanished about one billion years ago.
About four billion years ago, Mars lost the advantage of a dense atmosphere and a magnetic field, like on Earth, that sheltered the atmosphere from cosmic radiation from the Sun. Radiation now pierces one meter into the Martian surface and would kill even the healthiest microbes known on Earth.