Mars once had water on it that was warm enough to support life, evidence found on meteorites from the Red Planet has shown.
Researchers at the University of Leicester and The Open University found that hydrothermal fractures around Martian impact craters could have provided a habitable environment for microbial life.
Dr John Bridges, lead author and reader in planetary science at the University of Leicester Space Research Centre, said: "While the orbiters and rovers are studying the minerals on Mars, we also have meteorites from Mars here on Earth. They come in three different groups, the shergottites, the nakhlites and the chassignites. Of most interest for the question of water on Mars are the nakhlites, because this group of Martian meteorites contains small veins, which are filled with minerals formed by the action of water near the surface of Mars."
The study found that water temperatures on Mars ranged from 50 - 150 degrees Celsius. Microbes on Earth are able to survive in similar waters, such as in the volcanic thermal springs in Yellowstone Park.
One of the meteorites studies, named Lafayette, has the most complete succession of newly formed minerals in its veins.
Analysis of the minerals showed that the first mineral to grow along its veins was iron carbonate, which would have been formed by carbon dioxide-rich water of around 150°C. When the water cooled to 50°C, it then would have formed clay minerals present.
Bridges said the force heating the water could have been an impact into the surface of Mars.
"The mineralogical details we see tell us that there had been high carbon dioxide pressure in the veins to form the carbonates," Bridges said.
"Conditions then changed to less carbon dioxide in the fluid and clay minerals formed. We have a good understanding of the conditions minerals form in, but to get to the details, chemical models are needed."
Using data from both the University of Leicester and The Open University, the researchers were able to predict the water conditions on Mars.
Dr Susanne Schwenzer, from The Open University, said: "Before we had the detailed study of the nakhlite meteorites, we did not know that carbonates are forming first, followed by the clays. Therefore I was very excited to see the details of the new mineralogical study."
This follows other research suggesting Mars once had an environment that could support life. In September, the Mars Curiosity found ancient rivers on the Red Planet that could have provided a habitable environment for life.
Following this, scientists from National Autonomous University of Mexico found that Mars has similar rocks to those found in the Cuatro Ciénegas, where life is sustained despite difficult conditions.