Just when the world is abuzz about the possibility that the Mars Phoenix Lander will find evidence of liquid water and life-enabling conditions in the prehistoric Martian past, a new report throws a bucket of salty water on that enthusiasm.
Researchers studied geochemical findings from the Mars rover Opportunity, and now say that even if liquid water did exist on Mars in a warmer era in the planet’s history, it was probably too salty to support life — or at least, life as we know it.
Martian waters were 10 to 100 times saltier than the Earth’s typical seawater, according to the report in Science [subscription required], a salinity level which would kill all organisms that humans know of.
Here on Earth, life seems to have permeated every nook and cranny, from temperate oceans to million-year-old permafrost. But not every environment is hospitable. Curiously enough, it is the food industry that has explored these most extreme conditions. Cram the maximum amount of salt or sugar into a water solution–as in salting meat or making strawberry preserves–and microbes are hard-pressed to survive, much less grow. That’s because the ions of dissolved salt hold on to so many water molecules that few are left to support microbial life [ScienceNow Daily News].
While scientists are continually surprised by the harsh conditions that so-called “extremophiles” can withstand, the paper’s authors were not optimistic about the prospect of finding evidence of tough little bugs on Mars. “If there was any life on Mars, it would have needed to start off at high acidity and high salinity,” said Nicholas Tosca, the paper’s lead author and a postdoctoral researcher at Harvard. “[Life on Mars] would require biology that was completely different from any we know on Earth.”
…Some microorganisms, known as halophiles (Latin translation: salt lovers), can live in water with [salinity levels as high] as those Tosca believes existed on Mars, but he drew a major distinction between what life could tolerate and what life could begin in. Halophiles on Earth have evolved from less salt-loving ancestors over millions of years, and they didn’t originate in such harsh conditions [Wired News].
But some researchers wonder if the patches of dirt sampled by the Mars rover can be representative of the whole planet, and bring a more positive attitude to NASA‘s continuing quest to “follow the water.” Ben Clark, a Mars expert at Lockheed Martin Corporation who was not involved in the study, said the area at the Martian equator sampled by the rovers for this work is already known to be unusual. The region, called Meridiani Planum, was chosen partly for its high content of hematite—an iron oxide mineral—which makes it chemically unique to begin with. Regardless, he said, no single place should be seen as a global representative of Mars’s mineral composition.
“It is very difficult to simulate actual Martian conditions,” he said. “Whether organisms could evolve to survive or propagate under near-saturated conditions of [salts] is difficult to fully evaluate” [National Geographic News].
Mars may be the main focus for mankind’s extraterrestrial longings, but DISCOVER has reported that plenty of other researchers are directing their searches towards life-sustaining planets in other solar systems. The truth is out there — somewhere.
Images: NASA/JPL/Cornell/US Geological Survey
July 1st, 2008 at 4:25 pm
Is the salt in such high concentrations that any past ‘ocean’ boiled off and left behind too much salt? IE a supersaturate?
From this article it’s not clear. How is it determined that the water of the past was so salty? Could this one area have been a Dead Sea?
July 3rd, 2008 at 4:30 pm
You can be fairly sure that, in the early times of Martian development, when there was a great deal more water on Mars than there is now, salinity of the water was considerably less.
While the salt levels pose some inconvenience, I suspect that they also helped Mars to retain much of the water it has been able to hold.
I am interested in finding out more about which salts there are, and the proportions. It would also be nice to hear more about the speculations and debates about the data in real time.
I am not suggesting that those involved go off half-cocked, drawing conclusions before they are fully warranted. But NASA has been on the wrong persuasion road for a long time, and I see few signs that they realize it.
To get the political support and funding is not just a matter of convincing our representatives. You won’t budge them an inch if their constituency is not on board.
But decades of taxation without prospects of an extremely visible return, particularly with the intractable terrestrial problems we are facing now, competing for sharply reduced revenues, cannot continue to be the sole source of funding.
Venture capital, the private sector, needs to play a much larger role. And NASA
needs to welcome the participation of private enterprise instead of thinking of it as competition.
March 19th, 2009 at 9:38 pm
What I find stupid is that if life does or did exist on mars, it probably wouldn’t be any life humans know of, now would it? Whatever creature may or may not have survived there may have thrived in the salt.
August 13th, 2011 at 5:37 am
I really enjoyed your blog thumbs up!