Mars: New Clues to Life in ‘Lake Doughnut’

The evidence mounts for long-ago microbes in a vanished body of Martian water

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A mosaic of Mars made from a compilation of images captured by the Viking Orbiter 1.
USGS / NASA

A mosaic of Mars made from a compilation of images captured by the Viking Orbiter 1.

It’s easy to get excited about the prospect of finding life on Mars—so easy that scientists have been getting worked up again and again and again and again over the past century and more. But it’s also easy to get too excited. NASA, for one, has learned from experience that announcing evidence even for long-extinct life on the Red Planet is a risky business, since it’s so easy to be wrong.

That’s why the agency is being so careful about a suite of reports from the Mars Science Laboratory (MSL), better known as the Curiosity rover, which has been sniffing around the Red Planet since its August, 2012 landing. The six papers, just published in Science, make no claim that they’ve found even the slightest evidence of life.

But what they have found is hugely important nonetheless: convincing evidence of a lake that rippled on the Martian surface some 3.6 billion years ago and that would have provided a fertile habitat for bacterial life—assuming the bacteria were actually there. “This environment would have been almost earthlike,” says Caltech planetary scientist and MSL project scientist John Grotzinger, “in terms of geochemistry and in the presence of water.”

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The water wasn’t big news: evidence that Mars was once a very wet place has been coming in since the early 1970’s, when the Mariner 9 orbiter first spotted what looked uncannily like dry riverbeds. Subsequent orbiters and rovers, including Curiosity, have found increasingly persuasive clues that young Mars had abundant streams, rivers and lakes—and since water is the most basic requirement for life as we know it, the odds that Mars could have hosted some sort of biology have kept going up too.

But water gets you only so far: organisms need food as well, and that’s what Curiosity has now found—potentially, at least. By drilling into exposed sedimentary rock at a site nicknamed Yellowknife Bay, the rover has uncovered minerals containing hydrogen, oxygen, carbon, nitrogen and sulfur. That’s a virtual feast for bacteria known as chemolithoautotrophs, which thrive on Earth in sulfurous caves and around so-called hydrothermal vents on the sea floor.

The lake that sloshed within Curiosity’s landing site in Gale Crater all those billions of years ago would, says Grotzinger, have been “a few meters to tens of meters deep.” And it would have had an interesting shape. If you imagine a crater with circular walls and a mountain in the middle, the lake would be a doughnut-shaped body of water—a moat around the mountain. “Maybe it didn’t go all the way around,” Grotzinger says. “The most conservative interpretation is that you’d have one-third of a donut, filled with water to a relatively shallow depth.

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But that might have been enough. The water persisted, the scientists believe, for tens of thousands of years at least, and perhaps for hundreds of thousands. That was ample time for layered sediments to accumulate and eventually solidify, first into clay and then into mudstone, which preserved the clues that Curiosity studied a few billion years later. And it was perhaps ample time for life to get started.

The discovery of the ancient lake was, in a sense, incidental to the mission. Curiosity’s primary area of interest has always been Mount Sharp, the mountain in the middle. Just before the rover landed, however, what Grotzinger calls a “massive mapping exercise” revealed that Yellowknife Bay showed signs of ancient inundation, so instead of charging over to the mountain right away, Curiosity lingered in the Bay first.

The careful probing that followed with MSL’s cameras, mass spectrometers, X-ray diffractometers and other instruments culminated in the drilling of two boreholes into the solid rock, which in turn yielded proof of an environment hospitable to bacteria, if they existed. Not only were there plenty of delectable minerals available to snack on, but the water itself was evidently low in salt (“it was practically freshwater,” Grotzinger says), and neither especially alkaline nor especially acidic. “Ten years ago,” he says, “we found evidence for water, but the salinity was so high it would have had the texture of honey.”

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At first, the scientists worried that many of the minerals they found in the rock might have not have been present in the original lakebed itself, but might instead have been eroded from the crater walls and washed gradually into the lake. But the analysis revealed that the minerals showed few signs of weathering. They’d evidently been in the lake all along. “This lake is the original factory,” says Grotzinger, “where the clay was made.”

The absence of weathering does mean that while Mars was wet 3.6 billion years ago, it was also cold. “I like the analogy of the last glacial maximum on Earth,” says Grotzinger. At that time, about 25,000 years ago, much of the northern hemisphere was too cold for it ever to rain—something that weathers and erodes rocks relatively quickly—but water would still have pooled in low-lying areas. “Death Valley, the Las Vegas valley, those places would have been flooded,” he says. “I can imagine a scenario exactly like that.”

Put together, the new studies paint a picture of a hospitable place in which bacteria of a type we know exists on Earth could have thrived. The caveat—a big one—is that they say nothing at all about whether those bacteria in fact existed, though they do make an all but indisputable that that was possible.

The next step: look for organic carbon, which Curiosity will continue to do as it moves toward Mt. Sharp, its original target for exploration. “NASA has done really well with its ‘follow the water’ strategy,” Grotzinger says “Now we’re moving on to ‘follow the carbon,’” the other key element that all Earthly life, at least, is based on. And after that, in coming years, Mars exploration will inevitably move on to looking for fossil evidence of ancient  life—and just possibly, of any life that has managed to survive to this day, deep below the Martian surface.

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1 comments
BabuG.Ranganathan
BabuG.Ranganathan

ANY LIFE ON MARS CAME FROM EARTH

In the Earth's past there was powerful volcanic activity which could have easily spewed dirt and rocks containing microbes into outer space which not only could have eventually reached Mars but also ended up traveling in orbit through space that we now know as meteors. A Newsweek article of September 21, 1998, p.12 mentions exactly this possibility. "We think there's about 7 million tons of earth soil sitting on Mars", says scientist and evolutionist Kenneth Nealson. "You have to consider the possibility that if we find life on Mars, it could have come from the Earth" [Weingarten, T., Newsweek, September 21, 1998, p.12].

HAVING THE RIGHT CONDITIONS AND RAW MATERIALS FOR LIFE doesn't mean that life can originate by chance.

Proteins can't come into existence unless there's life first! Miller, in his famous experiment in 1953, showed that individual amino acids (the building blocks of life) could come into existence by chance. But, it's not enough just to have amino acids. The various amino acids that make-up life must link together in a precise sequence, just like the letters in a sentence, to form functioning protein molecules. If they're not in the right sequence the protein molecules won't work. It has never been shown that various amino acids can bind together into a sequence by chance to form protein molecules. Even the simplest cell is made up of many millions of various protein molecules.

The probability of just an average size protein molecule arising by chance is 10 to the 65th power. Mathematicians have said any event in the universe with odds of 10 to 50th power or greater is impossible! The late great British scientist Sir Frederick Hoyle calculated that the odds of even the simplest cell coming into existence by chance is 10 to the 40,000th power! How large is this? Consider that the total number of atoms in our universe is 10 to the 23rd power.

Also, what many don't realize is that Miller had a laboratory apparatus that shielded and protected the individual amino acids the moment they were formed, otherwise the amino acids would have quickly disintegrated and been destroyed in the mix of random energy and forces involved in Miller's experiment.

There is no innate chemical tendency for the various amino acids to bond with one another in a sequence. Any one amino acid can just as easily bond with any other. The only reason at all for why the various amino acids bond with one another in a precise sequence in the cells of our bodies is because they're directed to do so by an already existing sequence of molecules found in our genetic code.

Of course, once you have a complete and living cell then the genetic code and
biological machinery exist to direct the formation of more cells, but how could life or the cell have naturally originated when no directing code and mechanisms existed in nature? Read my Internet article: HOW FORENSIC SCIENCE REFUTES ATHEISM.

A partially evolved cell would quickly disintegrate under the effects of random forces of the environment, especially without the protection of a complete and fully functioning cell membrane. A partially evolved cell cannot wait millions of years for chance to make it complete and living! In fact, it couldn't have even
reached the partially evolved state.

Please read my popular Internet articles listed below:

ANY LIFE ON MARS CAME FROM EARTH,
SCIENCE AND THE ORIGIN OF LIFE,
NATURAL LIMITS OF EVOLUTION,
HOW FORENSIC SCIENCE REFUTES ATHEISM,
WAR AMONG EVOLUTIONISTS (2nd Edition),
NO HALF-EVOLVED DINOSAURS,
HOW DID MY DNA MAKE ME?
DOES GOD PARTICLE EXPLAIN UNIVERSE'S ORIGIN?

Visit my newest Internet site: THE SCIENCE SUPPORTING CREATION

Sincerely,
Babu G. Ranganathan*
(B.A. theology/biology)

Author of popular Internet article, TRADITIONAL DOCTRINE OF HELL EVOLVED FROM GREEK ROOTS

* I have had the privilege of being recognized in the 24th edition of Marquis "Who's Who In The East" for my writings on religion and science, and I have given successful lectures (with question and answer time afterwards) defending creation from science before evolutionist science faculty and students at various colleges and universities.