‘Results are very exciting, because they increase the possibility that there is life alive on Mars today,’ expert says
WASHINGTON — Liquid water has been observed on the planet Mars, the US space agency NASA said Monday.
“Mars is not the dry, arid planet we thought of in the past,” Jim Green, NASA’s planetary science director, told a press conference. “Under certain circumstances, liquid water has been found on Mars.”
Scientists have long believed that water once flowed freely across the red planet and was responsible for forming its valleys and canyons.
Major climate change about three billion years ago is believed to have changed all that, Green said.
“Today we’re revolutionizing our understanding of this planet,” Green said. “Our rovers are finding there’s a lot more humidity in the air.”
The rovers searching the planet’s surface have also found that the soil is much more moist than anticipated.
Dark streaks running down slopes on the Martian surface were observed about four years ago. Scientists did not have proof, however, that these streaks — which would form in spring, grow by summer and then disappear by fall — were actually water.
But after careful study and analysis, they are ready to say that these streaks may be streaks of super-salty brine, a team said after discovering evidence of “hydrated” salt minerals.
These results “strongly support the hypothesis” of liquid water on Mars — though not H2O as we know it, concluded a research paper in the journal Nature Geoscience.
If anything, it was likely “wet soil, not free water sitting on the surface,” study co-author Alfred McEwen, from the University of Arizona, told AFP. Asked if the data was the final proof of liquid water on Mars, McEwen replied: “I would say almost.”
The hydrated salt minerals, called perchlorites, contain water molecules in their make-up, and their presence indicates that “water plays a vital role in the formation of these streaks,” according to Lujendra Ojha of the Georgia Institute of Technology in Atlanta.
It is widely accepted that the Red Planet once hosted plentiful water in liquid form, and still has water today, albeit frozen in ice underground.
Earlier this year, NASA said almost half of Mars’ northern hemisphere had once been an ocean, reaching depths greater than 1.6 kilometers (one mile).
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Astrobiologist Lewis Dartnell of the University of Leicester Space Research Centre said the study, which he did not take part in, presented “very strong evidence that what we believe to be signs of liquid water trickling down the Martian surface is in fact that.”
This, in turn, raised the intriguing prospect of life, he told AFP.
“If there is liquid water trickling beneath the surface, maybe that’s an environment where bacteria and microbial life can survive… The results we’ve had this afternoon are very exciting because they increase the possibility that there is life alive on Mars today.”
Scientists have long hypothesized that the seasonal features, dubbed “recurring slope lineae” (RSL), may be formed by brine flows.
But spacecraft images have been unable to reveal detail of what exactly is in the lines — the pixel resolution is coarser than the width of the streaks themselves.
Up to a few hundred meters in length and typically under five meters (16 feet) wide, they appear on slopes during warm seasons, lengthen, then fade as they cool.
For the new study, a team from the United States and France devised a method to extract more data from individual pixels in images from the CRISM spectrometer instrument on NASA‘s Orbiter.
They found details “consistent with the presence of hydrated salt minerals that precipitate from water,” according to a Nature press release. Precipitation is the process of separating a solid material from a liquid solution.
“The findings strongly suggest a link between the transient streaks on Martian slopes and the flow of liquid brines,” it added.
This was not the first time perchlorites were found on Mars.
In April this year, a different team wrote in the same journal that perchlorate salts were “widespread” on the surface of our neighboring planet, and humidity and temperature conditions were just right for salty brines to exist.
Perchlorate is highly absorbent and lowers the freezing point of water so that it remains liquid at colder temperatures.
As reported by The Times of Israel