Several observations on Mars have suggested that the planet might currently harbor liquid water. The presence of liquid water on Mars is a big deal because water is required for life as we know it. A team of researchers has published a new paper that suggests any stable liquids on the surface of Mars today wouldn’t be suitable environments for known terrestrial organisms.
The scientists say that life on Earth, even in extreme forms, has certain environmental limits it can withstand. The researchers investigated the distribution and chemistry of stable liquids on Mars to understand if those environments would be suitable even to extreme Earth life. The scientists say that with the low temperatures and extremely dry conditions on Mars if a liquid water droplet was placed on its surface it would nearly instantaneously freeze, boil, or evaporate.
The only way the water could survive on the surface of the Red Planet would be if that droplet had dissolved salt in it. Saltwater, or brine, would have a lower freezing temperature and would evaporate at a slower rate than pure liquid water. Scientists say that salts are found across Mars and brines could form there. The team notes that there was evidence of brine droplets forming on the strut of the Phoenix lander.
Scientists note that some Martian salts can undergo a process called deliquescence. The processes when a salt is at the right temperature and relative humidity, it can take in water from the atmosphere to become a salty liquid. The team has been conducting experiments under simulated Martian conditions to study that type of reaction for many years. The team says it predicts what it has learned in the lab happens on the surface of Mars.
The highest temperature a stable brine will experience on Mars is -55-degrees Fahrenheit, which is well below the lowest temperature that we know life can tolerate. The team says that is has also shown on a planetary scale that the Martian surface and shallow substrate may not be suitable for terrestrial organisms because liquids only form at rare times and when they do form, only do so under harsh conditions. The team does note there could be undiscovered life on Earth that could tolerate those conditions.