What new has come from the recent methane findings on Mars?

Question

I was reading:

https://www.cnet.com/news/nasas-curiosity-rover-makes-surprising-methane-gas-discovery-on-mars/

And, yes, I realize that cnet is not a good source of information, however it's more the thought process that I'm questioning, not the credibility of the source.

It's a particularly riveting discovery because the methane levels discovered by the rover are about three times higher than previous detections, leading to some speculation the gas may be biological in origin.

Why would 3x the methane that we've detected previously be a red flag for potential life? Checking the NASA article, they seem to carefully step around using terms like "Extraterrestrial Life" or "Confirmed" and go as far to say "we don't have the technology to determine if it's biological in origin on Curiosity".

My question: Who is speculating that a 3x higher methane concentration could be due to life? Is it just cnet (who misspelled Earth as Eart) or are other people thinking this is more likely now that we've seen 3x high concentration too? Did this finding disprove any of the existing theories? I am using cnet as a reference to general media, a lot of articles are approximately this

Nasa article: https://www.nasa.gov/feature/jpl/curiosity-detects-unusually-high-methane-levels/

Answer 1

tl;dr: Except for the signal being 3x larger, at this point nothing new has been learned.

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The only thing new I can see is that the signal is 3x larger than the previous one recorded by Curiosity, removing any potential lingering doubt about the reality of signal, which at only 7 ppb was close to the error bars.

Source

Now at 21 ppb (3x larger than the 2013 whiff shown in the image above) it stands out clearly.

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So except for the signal being 3x larger, at this point nothing new has been learned.

NASA JPL News item from June 23, 2019 Curiosity's Mars Methane Mystery Continues says

The finding suggests last week's methane detection - the largest amount of the gas Curiosity has ever found - was one of the transient methane plumes that have been observed in the past. While scientists have observed the background levels rise and fall seasonally, they haven't found a pattern in the occurrence of these transient plumes.

"The methane mystery continues," said Ashwin Vasavada, Curiosity's project scientist at NASA's Jet Propulsion Laboratory in Pasadena, California. "We're more motivated than ever to keep measuring and put our brains together to figure out how methane behaves in the Martian atmosphere."

Curiosity doesn't have instruments that can definitively say whether the source of the methane is biological or geological. A clearer understanding of these plumes, combined with coordinated measurements from other missions, could help scientists determine where they're located on Mars. (emphasis added)

The first lines of the New York Times' With a Poof, Mars Methane Is Gone sums it up nicely as well:

Last week, NASA’s Curiosity rover detected a belch of natural gas on the red planet. The gas has since dissipated, leaving only a mystery.

Mars gave a good burp last week, but the gas has come and gone, leaving scientists no closer to knowing whether there is life on or beneath the red planet.

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There are still at least two completely different possible sources of atmospheric methane on Mars and the current data does not help to distinguish between them.

From Phys.org's A Martian methane belch melts away:

One leading theory is that the methane is being released from underground reservoirs created by long extinct life forms.

Though Mars has no active volcanoes like on Earth, it is also possible that methane is being produced by reactions of carbon from carbonate rocks or carbon dioxide, with hydrogen from liquid water. (emphasis added)

Answer 2

Since the readings were only taken a couple of days ago, it's too early.

From NASA's report:

Curiosity's scientists need time to analyze these clues and conduct many more methane observations. They also need time to collaborate with other science teams, including those with the European Space Agency's Trace Gas Orbiter, which has been in its science orbit for a little over a year without detecting any methane. Combining observations from the surface and from orbit could help scientists locate sources of the gas on the planet and understand how long it lasts in the Martian atmosphere. That might explain why the Trace Gas Orbiter's and Curiosity's methane observations have been so different.

There's a lot more research to be done before any meaningful interpretations of this (and future) data can be made.

Answer 3

This NASA article describes a recent experiment with Curiosity that show that methane levels rise and fall daily, which then explains the difference between the Curiosity and Trace Gas Orbiter measurements. (See also this answer).

However, it still does not explain the ultimate source of the methane.