Researchers from the Australian National University have determined that very large regions under the surface of the red planet may contain water and have sufficiently comfortable temperatures for Earth-based life -- albeit microbial life.
"We found that 3 percent of the volume of Mars is habitable in terms of having the right temperatures and pressures for liquid water and life," astrobiologist Charley Lineweaver told The Huffington Post by email. "The biggest surprise is that extensive regions of Mars could be habitable in terms of temperature, pressure and water."
Lineweaver is the leader of an ANU team that compared models of the similarities of pressure and temperature conditions between Earth and its nearest planetary neighbor, as pictured below.
"One can get a nice overview of where H20 is liquid, ice and vapor from a pressure-temperature phase diagram," he wrote. "That let us identify and distinguish between inhabited and uninhabited water on Earth, and we were surprised to find a lot of it on Earth."
After they practiced on our home planet, Lineweaver and his team applied the same technique to Mars. "In terms of pressure and temperature, Mars has a large habitable region."
But before we all start packing our bags and signing up for a relocation to Mars, Lineweaver says that this habitable region is most likely underground.
"The current atmospheric pressure on Mars is too low to allow liquid water. Ice just sublimates into vapor. It's hard to drink ice or vapor, and hard to mobilize nutrients in ice or vapor."
And it may be a bit premature to set up housekeeping on the red planet -- even underground -- because Lineweaver's findings don't necesssarily apply to humans.
"Our results are mainly relevant for microbes. However, for warmth, insulation and protection from cosmic rays, and to have enough pressure to keep water liquid, subterranean (or rather sub-Martian) human colonies with abundant water features may be the niche of choice for human colonization," he explained.
Lineweaver is co-author of a paper just published in the journal Astrobiology.
"If evidence for water is found in these environments, then they have a high potential of supporting terrestrial-like life," according to his team's eye-opening conclusions in the scientific journal.
And Lineweaver suggests all of this microbes-on-Mars news may help to solve the age-old question of where we all came from.
"By studying these potential life forms, we could learn fundamental things about life in general and about how we terrestrial life forms originated," he said. "There is also the possibility that we are all Martians in the sense that terrestrial life may have originated on Mars and been transported to Earth during the first half of our solar system a billion years ago."
The astrobiologist added that the bitter cold Martian surface temperature wouldn't be too brutal for humans.
"Think Antarctica," he offered. "Very cold but tolerable if appropriately dressed."
When NASA's next robot rover, Curiosity, lands on the red planet in August 2012, scientists hope it will transmit more positive data back to Earth on the possibilities of water and life on Mars.