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Odds Of Life On Mars Appear Low

Mars Curiousity

New findings from the Curiosity rover seem to indicate little evidence of life on Mars:

In findings that are as scientifically significant as they are crushing to the popular imagination, NASA reported Thursday that its Mars rover, Curiosity, has deflated hopes that life could be thriving on Mars today.

The conclusion, published in the journal Science, comes from the fact that Curiosity has been looking for methane, a gas that is considered a possible calling card of microbes, and has so far found none of it. While the absence of methane does not rule out the possibility of present-day life on Mars — there are plenty of microbes, on Earth at least, that do not produce methane — it does return the idea to the realm of pure speculation without any hopeful data to back it up.

The history of human fascination with the possibility of life on Mars is rich, encompassing myriad works of science fiction, Percival Lowell’s quixotic efforts to map what turned out to be imaginary canals, Orson Welles’s panic-inducing 1938 “War of the Worlds” radio play, and of course Bugs Bunny’s nemesis, Marvin the Martian.

But Marvin apparently did not emit enough methane for Curiosity’s sensitive instruments to find him.

“You don’t have direct evidence that there is microbial process going on,” said Sushil K. Atreya, a professor of atmospheric and space science at the University of Michigan and a member of the science team.

But NASA scientists are going strictly by their data, and they are leery about drawing broader implications to the question once posed by David Bowie, “Is there life on Mars?” John P. Grotzinger, the project scientist for the Curiosity mission, would go only so far as to say that the lack of this gas “does diminish” the possibility of methane-exhaling creatures going about their business on Mars.

“It would have been great if we got methane,” Dr. Atreya said. “It just isn’t there.”

Curiosity, which has been trundling across the planet for a little over a year, made measurements from Martian spring to late summer, coming up empty for methane.

Scientists have long thought that Mars, warm and wet in its early years, could have been hospitable for life, and the new findings do not mean that it was not. But that was about three and a half billion years ago. Methane molecules break apart over a few centuries — victims of the Sun’s ultraviolet light and of chemical reactions in the atmosphere — so any methane in the air from primordial times would have disappeared long ago.

That is why reports of huge plumes of methane rising over Mars in 2003 fueled fresh hopes for Martian microbes. Those findings, based on data from telescopes on Earth and a spacecraft orbiting Mars, set off a surge of speculation and scientific interest.

On Earth, most of the methane comes from micro-organisms known as methanogens, but the gas is also produced without living organisms, in hydrothermal vents. Either possibility would be a surprising result for Mars.

After the 2003 methane readings, “a lot people got excited and started working on it,” said Christopher R. Webster of NASA’s Jet Propulsion Laboratory in Pasadena, Calif., and the lead author of the paper in Science. “It was a very important result, because of the magnitude of methane.” The fresh data from Curiosity brings the earlier claims into question.

Not everyone is daunted. Robert Zubrin, president of the Mars Society, a nonprofit group dedicated to the planet’s exploration and settlement, said he was still convinced that Martian life was waiting to be discovered in underground aquifers.

“If it had found methane, that would have been killer,” Dr. Zubrin said, referring to Curiosity. “Yes, it’s disappointing in that we didn’t get a pony for Christmas. But it doesn’t mean there aren’t ponies out there.”

One of the scientists who found the methane plumes in 2003, Michael J. Mumma, of NASA’s Goddard Space Flight Center in Greenbelt, Md., said in an interview this week he was certain that his earlier measurements were still valid. He said he now believed that methane on Mars was episodic — released in large plumes and then quickly destroyed. He suggested, half-jokingly, that there could be huge colonies of methane-eating microbes on Mars that eliminated the gas from the air.

Dr. Mumma acknowledged that he could not identify any phenomena that would explain why methane plumes spurted out that year but not more recently, or how methane could be destroyed much more quickly on Mars than on Earth.

“Mars may not be operating the same way,” he said. “It’s a puzzle.”

One can hope, but for the moment Mars appears to be a barren world. The question now is whether that was always the case.

 

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About Doug Mataconis
Doug holds a B.A. in Political Science from Rutgers University and J.D. from George Mason University School of Law. He joined the staff of OTB in May, 2010 and also writes at Below The Beltway. Follow Doug on Twitter | Facebook

Comments

  1. Cleve Watson says:

    “While the absence of methane does not rule out the possibility of present-day life on Mars … it does return the idea to the realm of pure speculation without any hopeful data to back it up.”

    The amusing thing is that is was ALWAYS pure speculation. Wishful thinking has gotten WAY ahead of facts in the area of extraterrestrial life.

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  2. john personna says:

    @Cleve Watson:

    Unavoidably, because while we have one known example of a living planet, we cannot know the “envelope” of possible living worlds. We don’t know the boundary conditions, nor the kinds of things that live near them.

    Like or Dislike: Thumb up 3 Thumb down 0

  3. Tyrell says:

    Why not declassify the huge amount of information, photos, and videos that they are keeping secret ?

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  4. John Burgess says:

    And when, in a decade, they discover the presence of Martian methanovores…

    Like or Dislike: Thumb up 2 Thumb down 0

  5. al-Ameda says:

    I’m guessing that when scientists programmed the Rover they took into account Newt Gingrich’s plans to personally colonize Mars and petition for statehood?

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  6. Brett says:

    There could still be life deep underground, which is also honestly the only place you might still find any liquid water on Mars. But since we’re not about to go drilling more than a few inches into the Martian surface anytime soon, that doesn’t help us. For all intents and purposes, there’s probably no Martian life at or near the surface.

    It’s weird, though, that they didn’t pick up any methane. Both Earth-based telescopes and some of the orbiting satellites had picked up signs of methane over the past 15 years, but that must have just been a big mistake on all their parts, unless there’s some way that Martian methane is getting yanked out of the atmosphere faster than expected.

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  7. Brett says:

    @Cleve Watson

    The amusing thing is that is was ALWAYS pure speculation. Wishful thinking has gotten WAY ahead of facts in the area of extraterrestrial life.

    To be fair, they had been getting methane readings from telescopes and Mars Express for a couple of years, and that’s not something to dismiss (atmospheric methane is considered to be one of the big potential tells for whether or not there’s active life).

    I do agree that they tended to be rather . . . excitable about anything even remotely hinting that life might have once been possible on Mars, like with that water confirmation.

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  8. Dave D says:

    @Brett: I had heard but no longer remember the source that the presence of methane could have been indicative of one of two things either life in the form of methanogens or that the core of mars was still geothermally active. The later of which is still under debate.

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  9. anjin-san says:

    Why not declassify the huge amount of information, photos, and videos that they are keeping secret ?

    Secret videos from Mars? Dude, where are you getting this stuff?

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