Theoretical origin of life; possibly on Mars (Introduction)

by David Turell , Friday, June 08, 2018, 00:44 (2360 days ago) @ David Turell

There is new organic compound evidence from Mars:

http://blogs.discovermagazine.com/d-brief/2018/06/07/curiosity-rover-finds-organics-hid...

"In a much-hyped press conference held on Thursday, NASA announced its Curiosity rover had uncovered new evidence of methane — a potential sign of life — as well as signs of organic compounds buried in ancient mudstone.

"The space agency did not say it had found evidence of alien life. However, these new results are still tantalizing.

***

"In the first paper, a team analyzed three Mars years worth (55 Earth months) of atmospheric data from Curiosity. In that time, the rover caught methane levels spiking as the seasons changed, growing several times stronger at the height of summer in the northern hemisphere.

"Based on the chemical make-up, the scientists suspect this methane was heated up and released from sub-surface reservoirs where it was likely trapped in permafrost. They suspect large amount of the gas may be frozen in such underground reservoirs. But its exact origin remains a mystery.

"The other study, led by NASA biogeochemist Jennifer Eigenbrode, examined drill samples of three-billion year old mudstones that Curiosity collected from two different sites in Gale Crater. The rover dropped these samples into an onboard laboratory and cooked them in order to analyze the gasses they threw out.

"According to Eigenbrode’s team, the rocks released organic molecules much like those found in organic-rich rocks on Earth. And intriguingly, these molecules seem to have broken off of bigger and more complex molecules — the kinds found in coal and shale on Earth.

"This is far from the first time Mars researchers have claimed to find methane. Curiosity itself made headlines in recent years after seeing faint methane signals. But scientists have been chasing this gas for decades.

***

"All this means that, on Earth, methane is a sign of life. That’s given astronomers good reason to see methane as a potential signal of microbes on Mars.

Like Earth, it also has methane-destroying conditions. The Red Planet’s atmosphere is almost completely made of carbon dioxide. And even the ultraviolet light that penetrates Mars’ weak atmosphere could destroy it.

"So, any methane we do see must have been released into the atmosphere very recently.
But life isn’t the only process that makes methane. We know that because it’s abundant on Uranus and Neptune. And there’s enough of the stuff to create bizarre landscapes on the surfaces of Pluto and Titan. And even on Earth, a small amount of methane is made in specific sorts of volcanic reactions, even if it doesn’t stick around long.

"But Mars has no active volcanoes. And it doesn’t have ways of replenishing methane like those outer solar system worlds."

Comment: In an earlier time Mars could have had life. But did Mars have a floating crust with plate tectonics which is a requirement? Exciting, but?