Hardy bacteria similar to that found in the most inhospitable places on Earth may be thriving on the red planet.
Experiments that mimicked conditions on Mars discovered that unusual salts in liquid water below the planet’s frozen surface prevent liquid water from freezing.
Microbes similar to those found within Arctic glaciers, at the bottom of the deepest oceans and even underneath volcanoes, may be able to flourish in this environment.
Hardy bacteria similar to that found in the most inhospitable places on Earth may be thriving on the red planet. Experiments that mimicked conditions on Mars found that unusual salts in liquid water below the planet’s frozen deserts prevents it from freezing
A research team led by the University of Leeds analysed what they refer to as ‘mimetic Martin water’, to better understand how liquid water could exist on the Martian surface.
Surface temperatures on Mars may reach a high of about 20°C (68°F) at the equator and as low as -153° C (-243°F) at the pole.
With an average surface temperature of -55°C (-67°F), water itself cannot exist as a liquid on Mars.
Martian soil samples gathered by the Phoenix Lander in 2009 found calcium and powerful oxidants, including magnesium perchlorate, which can survive these low temperatures.
This fuelled speculation that perchlorate brine flows might be the cause of river-like channels and other weathering observed on the planet’s surface.
By studying the structure of water in a magnesium perchlorate solution, the research team found the salts have an effect equivalent to pressurising pure water to two billion pascals or more, which would prevent it from freezing.
Dr Lorna Dougan, from the university’s school of physics and astronomy said: ‘The discovery of significant amounts of different perchlorate salts in Martian soil gives new insight into the Martian “riverbeds.”
‘If the structure of Martian water is highly pressurised, perhaps we might expect to find organisms adapted to high pressure life similar to piezophiles on Earth, such as deep sea bacteria and other organisms that thrive at high pressure.
‘This highlights the importance of studying life in extreme environments in both terrestrial and non-terrestrial environments so that we can fully understand the natural limits of life.’
Bacteria has been discovered in some of Earth’s unlikeliest places, from miles below the ocean’s surface to deep within glaciers.
Martian soil samples gathered by the Phoenix Lander in 2009 found calcium and powerful oxidants, including magnesium perchlorate. This graph shows the lab analysis of the ‘Mars water’ brine solution
Concentrated solutions of perchlorate could survive the low temperatures on Mars. This graphic shows the distributions of water and magnesium around a central perchlorate ion
It has even been found in a hole drilled more than 4,000 feet deep in volcanic rock on the island of Hawaii near Hilo, in an environment believed to be similar to conditions on Mars and other planets.
Liquid water is traditionally considered an essential ingredient for life as we know it, and organisms on Earth, halophiles, can survive in such salty environments.
Measurements from the Mars Curiosity rover taken at the Gale crater show during winter nights until just after sunrise, temperatures and humidity levels are just right for liquid brine to form.
When mixed with water, this brine can exist down to around -70°C (-94°F), and the salt also soaks up water vapour from the atmosphere.
The research team used both lab tests and computer modelling to refine and analyse the structure of their ‘Martian water’ brine substitute.
This graphic shows the spatial density of the brine solution, with pressure forcing the shell of the compound to collapse in on the central water molecule, preventing it from freezing
Observations showed charged hydrogen ions become partially segregated in the salty solution.
It is likely that this is what stops the water from freezing.
Dr Dougan added: ‘We found these observations quite intriguing.
‘It gives a different perspective of how salts dissolve in water.
‘The magnesium perchlorate is clearly a major contributing factor on the freezing point of this solution and paves the way for understanding how a fluid might exist under the sub-freezing conditions of Mars.’
The full findings of the study were published in the journal Nature Communications.
MARS: A WET PLANET
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 scientists previously 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 H2O 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.