'Building blocks' for life discovered on Mars

[ChasFink]

'Building blocks' for life discovered in 3-billion-year-old organic matter on Mars

https://www.usatoday.com/story/news/...ter/681597002/

The "building blocks" for life have been discovered in 3-billion-year-old organic matter on Mars, NASA scientists announced Thursday.

Researchers cannot yet say whether their discovery stems from life or a more mundane geological process. However, “we’re in a really good position to move forward looking for signs of life," said Jennifer Eigenbrode, a NASA biogeochemist and lead author of a study published Thursday in the peer-reviewed journal Science.

The findings were also remarkable, in that it showed that organic material can be preserved for billions of years on the harsh Martian surface.

[DrRocket]

The study also showed there are seasonal spikes in the amount of methane in the atmosphere, the amount almost tripling during these spikes.

I have to admit, this is ground-breaking stuff that has me pretty excited.

[thorny locust]

complex organic molecules that look strikingly similar to the goopy fossilized building blocks of oil and gas on Earth

Question for those who might know:

Would any organic molecules be essentially similar to the ones on Earth, just by the definition of the term; or would similarity in itself be an important thing to discover, as implying either a direct relation at some point (as in, organic molecules being seeded on both planets from space) or as telling us something about the likelihood that life elsewhere in the universe might be starting from similar points?

-- I hope that question makes sense; I'm not sure my level of knowledge is even good enough to phrase the question right.

(Of course, I don''t know what the authors mean by "strikingly similar", either.)

[ChasFink]

I'm no expert, but I'll give it a whirl.

I believe "organic molecules" technically only means there's carbon and some hydrogen in them. But those molecules are the stuff that "life as we know it" is based on.

My understanding is that the discovery shows that the chemicals that eventually led to life on Earth were also present on Mars in the past, and that the conditions were somewhat similar. Not proof of life by a long shot, but a lot closer to proof than we've been up to this point.

[iskinner]

And about as close as we can currently get with the technology on the rovers presently on the surface of Mars. This discovery/announcement is a strong impetuous for a planned future Mars mission that will have instrumentation specifically designed to detect signs of actual life.

[Richard W]

It's kind of hard to say from just that line. "Organic molecules" mean molecules based on carbon and hydrogen, with the carbon forming chains. If they say they're "strikingly similar" to those on earth then it may imply they've found something more specific, or it may not.

The only molecule that story mentions specifically is methane, which is the simplest organic molecule there is, and by definition it's the same as methane on earth - barring subtle differences in the isotopic ratios and things which are more physics than chemistry, and probably not relevant. They say its presence suggests biological sources when found on earth, but it certainly can arise just from chemical processes too.

The other thing they mention is "gas", which I assume means "gasoline" here. I think it will be the journalist who's used that comparison, though. Crude oil is distilled into various longer-chain hydrocarbons such as ethane, propane, butane and so on (distinguished by the number of carbons in the chain - methane = 1, ethane = 2, propane = 3 etc...). Again, these are pretty simple molecules that can arise from various processes, but on earth, crude oil is the fossilised and compressed remains of biological life. By definition if these are the molecules they've found they will be "strikingly similar" to the same molecules on earth, but again, the comparison with fossil fuels is misleading because they can come from other processes, and they're very simple molecules.

If they've found anything more complex than that, it's not evident from the article. On the other hand, just finding carbon chains is interesting in itself - they are the "building blocks of life" as it says, but finding the blocks doesn't imply they've actually been built into life in the past and then fallen apart again.

[thorny locust]

Thanks, all.

So if they have found something more complex, then information could be deduced from whether it's "strikingly similar" to terrestrial forms; but if they've just found basic molecules, then of course they're similar?

-- it is indeed difficult to tell from that article; but I suspect it's basic forms that they've found, because I would have expected it to be a very big deal, and therefore to be pointed out, if they'd found complex versions. Not that this isn't a big deal; but that would be a bigger one.

[iskinner]

An important distinction is that they do not know if they have found more or not. The uncertainty here is that we currently do not have a way to get a more complete answer from the technology available. The samples that have been investigated could have very well had more to tell, but we can't read it yet.

Planned future missions are being designed to do just that. To bring the technology to examine finds like this more closely for signs of life past or present.

But until we had the information announced this week and some earlier findings there was not enough evidence to justify expending the weight and cost of adding such implementation to earlier missions.

[Crius of CoH]

Reminds me of the original Viking lander results, immortalized (sort of) by a poem that appeared in the May 1977 issue of Analog magazine.

For the link-wary (or -weary):

What's in Store?
John A. Carroll

Once upon a planet dreary
Came a rocket engine cheery
On a flight to test a theory
On Mars's frigid desert floor!

Did life arise spontaneous
Or some alien's trash extraneous
Seed the globe that now contains us?
Quoth the Lander, "Either-or."

[ChasFink]

Thanks, Crius of CoH, I had all but forgotten that poem!

For those who are too young to remember, Viking was supposed to prove definitively if there was life on Mars. If the chemical test results went one way yes, the other way, no. There was a huge gap between the two so there would be no doubt. The results came up somewhere in the middle. After a long analysis most (not all) biochemists said that that it was freaky chemistry, but not life.

The current results, if I understand them, are less ambiguous. They point in the direction of life (at least in the past) but are not detailed enough to prove it.