NASA data shows that the surface is too cold to support liquid water. However, Curiosity’s Curiosity Rover has collected enough data to prove this. Scientists have revealed that salts found in Martian soil lower the freezing point of water, which allows briny films to form. NASA scientists explain in Nature Geoscience how thin water films are created when salts (perchlorates) absorb water vapour. They stated that these super-cold liquid films (about -70degC) are unlikely to support life as it is now. Onboard Marsrover Curiosity is the meteorological station REMS. Image: NASA/JPL–Caltech. The Martian soil’s top 15cm layer contains brines. These brines are exposed to high levels of cosmic radiation. This further decreases the possibility of any living microbial organisms. Conditions might be more favorable for life below the surface. NASA scientists collected data using Curiosity’s scientific instruments to determine Mars’ water cycle. REMS, the weather station of Curiosity, measured relative humidity and temperature at Gale Crater, which was once home to a lake. See picture below. The team could estimate the concentrations of water below Mars’ surface using data from DAN (Dynamicalbedo of Neutrons), a scientific instrument. The team discovered that water on Mars was bound to perchlorates. SAM (Sample Analysis of Mars) provided information on the atmospheric water levels. Scientists concluded that the conditions for brine formation at Red Planet’s Equator in winter night were perfect. However, they would quickly evaporate once the Sun rose in the morning. The lead author of the discovery, Professor Javier Martin Torres from Lulea University of Technology, Sweden. He is also part of Curiosity’s science team, as well as the Spanish Research Council. The illustration shows a partially filled Gale Crater with water. Scientists think it once had water. Image: NASA. Prof. Martin-Torres stated that what they see is the environment for brine formation on the surface. This is similar to the time when exoplanets were discovered. Although they weren’t able to observe the planets themselves, they could see their gravitational effects. They absorb water vapour in the atmosphere to make brines. It is important to observe a daily water cycle. The brine helps maintain this cycle. The exchange of water between ground and atmosphere is possible on Earth. This is not the case on Mars. Mars has a lower temperature where brines can form. These brines were found near the Equator. Scientists believe that they form in colder temperatures. They are likely to be more common at higher latitudes, farther away from the Equator. Higher latitudes are where humidity and temperature are higher. Alfred McEwen (University of Arizona), Tucson Principal Investigator for HiRISE, was co-author. He said that Gale Crater has the lowest likelihood of brines forming in Mars than sites with higher latitudes and more shade. Professor Martin-Torres believes that brines could exist at high latitudes. This could explain why brines could persist at other places. Ashwin Vasavada (Curiosity Project Scientist), who is based at NASA’s Jet Propulsion Laboratory in Pasadena in California said that while we haven’t detected brines in Gale Crater, it has been suggested by co-author. “The value of REMS’s round-the-clock, year-round measurement can be seen in Mars’ relative humidity. It ranges between 100% on winter nights and about 5% in summer afternoons. Reference: F. Javier Martin-Torres, David Vaniman, Maria-Paz Zorzano, Patricia Valentin-Serrano, Pamela Conrad, Ari-Matti Harri, Maria Genzer, Dawn Sumner, Osku Kemppinen, Edgard G. Rivera-Valentin, Ashwin R. Vasavada, Insoo Jun, James Wray, Morten Bo Madsen, Walter Goetz, Gilles Berger, Alfred S. McEwen, Charles Cockell, Craig Hardgrove, Tim McConnochie, Nilton Renno, Vincent F. Chevrier, Jesus Martinez-Frias, Michael Mischna, and Rafael Navarro-Gonzalez. Nature Geoscience. Published. Publication 13 April 2015. DOI: 10. 1038/ngeo2412.
