Methane spike detected on Mars


"The NASA Curiosity rover made a remarkable discovery this week that may hint at signs of life on Mars.

The surprising development, reported on by The New York Times, brings legitimacy to the long-held notion that aliens may actually be occupying the red planet.

According to a measurement taken on Wednesday by NASA's Curiosity rover, scientists unearthed high amounts of methane in the air on Mars — indicating microbes could survive on the planet. As The Times noted, methane is typically just produced by living things.

Business Insider has reached out to NASA for comment.

This isn't the first time that scientists have found methane on Mars: In 2004, scientists reported the discovery of methane in the air, following three year's of observations. "We are 99 percent confident," Dr. Michael Mumma, a senior scientist at NASA's Goddard Space Flight Center, told The Times following that news. "It surprised all of us, actually. We really are still scrambling to understand what it means."

However, in 2013, new measurements from the Curiosity rover found that the atmosphere contained very little or no methane, reducing the prospect of life on the planet. Study author Christopher Webster, director of the microdevices lab at NASA's Jet Propulsion Laboratory, described those results as "disappointing for many," in a 2013 interview with Business Insider.

According to an email obtained by the Times, Ashwin R. Vasavada, the project scientist for the mission, wrote to his team that "given this surprising result, we've reorganized the weekend to run a follow-up experiment," with the results of those observations expected on Monday."
There have been indications of methane on Mars before.  

They say that on Earth, methane is about 1,800 parts per billion by volume (ppbv). In 2004, the Mars Express orbiter detected methane on Mars at about 10 ppbv. Earth based telescopic observations have reported between 0 and 45 ppbv. NASA's Curiosity then charted a background level of methane in the Martian atmosphere of between 0.2 and 0.7 ppbv. But Curiosity has also noted occasional spikes in those numbers. At least one of those spikes detected by Curiosity was also observed by Mars Express. (So it wasn't just instrumental noise.)

Then Russia's Roscosmos sent a mission to Mars that arrived in 2016. A planned lander failed and crashed, but a satellite was put into orbit around Mars called the Trace Gas Orbiter. This has very sensitive instruments, some provided by the European Space Agency, for determining the chemical composition of the Martian atmosphere, particularly its rarer trace gases. And the Trace Gas Orbiter found very little methane. They got a value of .012 ppbv with an upper limit of .05 ppbv. Much lower than the Curiosity numbers.
So, if Curiosity is currently detecting methane, it might be experiencing one of those transient methane spikes that have been hypothesized to happen. I'd love to hear how much methane they are currently observing.

The thing with methane is that solar radiation breaks it down in the atmosphere. It doesn't last. So if methane is being observed, it has have been produced relatively recently. On Earth, about 95% of the observed methane is produced by life, by microbial metabolisms. But there are inorganic processes that can produce methane as well.

So, given the very small amount of methane observed on Mars and given the possibility that it's inorganic, this Curiosity methane find isn't a slam-dunk indication of life on Mars by any means.

Edit: This Teslerati story says that the level that Curiosity detected this week was 21 ppb. That looks like a pretty high value, but still lower than the all-time high of 45 ppb observed by the Earth-based Keck observatory in Hawaii (University of California, Cal Tech and NASA).

So it looks like the amount of methane in Mars' atmosphere might be variable, ranging from near zero to about 2% of the concentration in Earth's atmosphere. Considering that some 5% of Earth's methane seems to be inorganic, and Mars is smaller, 2% might be what we would expect if Mars is producing inorganic methane at about the same rate. (Which it very likely isn't.)

So I still think that it's unclear what's happening. But it isn't necessarily evidence of life, even if it's consistent with life.

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