Washington: Using a radar instrument on an orbiting spacecraft, scientists have spotted what they said on Wednesday appears to be a sizeable salt-laden lake under ice on the southern polar plain of Mars. They went on to call the body of water a possible habitat for microbial life.
The reservoir they detected – roughly 12 miles (20 km) in diameter, shaped like a rounded triangle and located about a mile (1.5 km) beneath the ice surface – represents the first stable body of liquid water ever found on Mars.
Whether any place other than Earth has harboured life is one of the supreme questions in science and the new findings offer tantalising evidence, though no proof, given that water is considered a fundamental ingredient for life.
The researchers said it could take years to verify whether something is actually living in this body of water that resembles a subglacial lake on Earth. A probe could perhaps be undertaken through a future mission drilling through the ice to sample the water below.
“This is the place on Mars where you have something that most resembles a habitat, a place where life could subsist,” said planetary scientist Roberto Orosei of Istituto Nazionale di Astrofisica in Italy, who led the research published in the journal Science.
“This kind of environment is not exactly your ideal vacation, or a place where fish would swim,” added Orosei. “But there are terrestrial organisms that can survive and thrive, in fact, in similar environments. There are micro-organisms on Earth that are capable of surviving even in ice.”
The detection was made using data collected between May 2012 and December 2015 by an instrument aboard the European Space Agency’s Mars Express spacecraft that transmits radar pulses which penetrate the Martian surface and ice caps.
“It took us long years of data analysis and struggles to find a good method to be sure that what we were observing was unambiguously liquid water,” said study co-author Enrico Flamini, chief scientist at the Italian Space Agency, during the research.
The location’s radar profile resembled that of subglacial lakes found beneath Earth’s Antarctic and Greenland ice sheets.
Mars long ago was warmer and wetter, possessing significant bodies of water, as evidenced by dry lake beds and river valleys on its surface. There had currently been some signs of liquid water on Mars, including disputed evidence of water activity on Martian slopes, but no stable bodies of water.
Orosei said the water in the Martian lake was below the normal freezing point but remained liquid thanks, in large part, to high levels of salts. Orosei estimated the water temperature at somewhere between 14 degrees fahrenheit (minus 10 degrees celsius) and minus 94 degrees fahrenheit (minus 70 degrees celsius).
It remains to be seen if more subsurface reservoirs of water will be found or whether the newly discovered one is some sort of quirk, said Orosei.
If others are detected and a network of subglacial lakes exists on Mars like on Earth, it could indicate that liquid water has persisted for millions of years or even dating back to three and a half billion years ago when Mars was a more hospitable planet, he said.
The question would be, Orosei added, whether any life forms that could have evolved on Mars long ago have found a way to survive until now.
“Nobody dares to propose that there could be any more complex life forms,” said Orosei.
(Reuters)