Asteroid Contains Building Blocks of Life, Say Scientists (bbc.com) 53
Mr. Dollar Ton shares a report from the BBC: The chemical building blocks of life have been found, among many other complex chemical compounds, in the grainy dust of an asteroid called Bennu, an analysis reveals. Samples of the space rock, which were scooped up by a Nasa spacecraft and brought to Earth, contain a rich array of minerals and thousands of organic compounds. These include amino acids, which are the molecules that make up proteins, as well as nucleobases -- the fundamental components of DNA. The findings are published in two papers in the journal nature.
Where did they originate? (Score:3)
The minerals have probably been there since the asteroids were formed, but the organic compounds are practically weightless and have probably been blown up there from Earth. Further analysis should give an indication as to whether this is the case and roughly when they made it up there.
In a way that's a pity, if life on Earth was initiated from asteroidal seeding material, that would be an indication that life is more widely spread than just in our system. If life on Earth was initiated from up there, how did the asteroids avoid being heat-sterilised on their way down?
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In a way that's a pity, if life on Earth was initiated from asteroidal seeding material, that would be an indication that life is more widely spread than just in our system.
I don't... I ...
What?
Re: Where did they originate? (Score:1)
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There are those who believe that life here began out there⦠far across the universe, with tribes of humans who may have been the forefathers of the Egyptians or the Toltecs or the Mayans. Some believe that there may yet be brothers of man who even now fight to survive somewhere beyond the heavens. Fleeing from the Cylon Tyranny, the last Battlestar â" Galactica â" leads a rag-tag fugitive fleet on a lonely quest. A shining planet, known as Earth.
Muust Resist...No..NO! Agghh. Cannot resist!!
Might as well get it over with.
We all know that life began in Uranus!
There - I said it!
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And as soon as you dive into faster-than-light travel and the unavoidable complexities, visiting extraterrestrials are unlikely.
You first need a non-relativistic drive. Since our understanding of physics is greatly limited by relativity, we have no way to perceive such a thing. How we could generate the phenomena necessary to achieve this is beyond comprehension, I think. Even the Alcubierre drive is not merely theoretical but inadequate in many respects. Ignoring the energy requirements, the likely actual
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What are you talking about?
Everyone knows we achieved warp in the 21st century just after ww3. Zefram Cochrane did it out in the woods with scrap parts he gathered from the nearby junkyard. Every school kid knows this to be true.
It's not that hard.
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Actually, you're way ahead of the curve.
Time travel based on warp drive solves the relativistic issues. Think it through.
It breaks relativity, or enlarges it, depending on who you work for, or a variety of pharmacological factors, mostly non-prescription. No harm done.
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I'm pretty sure folding space in on itself does not create any sort of time travel bubble in and of itself, per se.
That requires creating a tachyon bubble with the deflector grid offset by the dilithium vibrational frequency at warp 8.21.
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Re:Where did they originate? (Score:5, Informative)
The chirality of the found compounds doesn't exhibit the preference typical (left) for life on Earth, so quite unlikely to be of Earth organic origin.
The real publications (in Nature) are free to read, and answer your other questions as well.
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Doesn't much matter. You'd have to demonstrate that, under astroid surface conditions, the lifetime of chirality amino acid molecules is at least comparable to the "churn" period for overturn of their soils by micrometeorite-churning (there is at least one person with training in soil science in this conversation ; I'm happy to consider them soils). For any asteroid in the "NEA" category, which can at least
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Re:Where did they originate? (Score:4, Interesting)
Actually no. We know that there are organic compounds in extra-terrestrial bodies since the 1970ies. If you analyze the spectra of comet tails, you find absorption lines from organic compounds like methane, ribose and lysine.
But not the complex organics found here; particularly a large variety of the amino acids that terrestrial life uses to build proteins, and all four of the molecular components that form DNA, adenine, guanine, cytosine and thymine.
The molecular soup of water ice, carbon dioxide and lots of dirt, together with a bombardment by sunlight, solar wind and cosmic rays creates the conditions for those molecules to synthesize,
That's the hypothesis, yes. The details have been hard to pin down. But this shows that some of the complex organics may form outside the terrestrial environment.
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You know that the lysine I mentioned is an amino acid?
Yes. You know that the phrase "a large variety of" I mentioned means "more than one"?
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The outer part of a meteor will heat up and melt away, but the interior of whatever remains on impact stays cold.
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I think that's irrelevant, because I believe that this is from a sample-return mission. (Bemu is still out there.)
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Re: Where did they originate? (Score:2)
Nonmetallic asteroids/comets can be formed as basically semi-loose aggregation of dust and small rocks correct? Is it such a leap to think that the more complex (heavy) molecules could naturally gravitationally seperate and sink to the interior from the perturbations of flying through the solar system and getting hit by the occasional small rock? Then that mass eventually enters an atmosphere at a shallow angle, the outer layer peels away, and you get a big poof of still relatively cool interior matter with
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"Heavy" in this context means high molecular mass, not high density (mass per unit volume).
I agree that Bennu, judging from it's surface features and structure, is a "rubble pile" asteroid. As such it's most likely composition is O(10%) ("order-of 10%, m/m") nickel-iron (den
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I wouldn't be surprised if some pre-solar grains were found in CAIs (calcium-aluminium-rich inclusions) in chondrite fragments in the body which showed (say) pre-solar samarium-neodymium dates. I would be much more surprised if such old grains made up even 1% of the datable grains in the sample.
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The range of masses where cold material gets to the surface and stays cold for minutes to hours after landing is quite narrow.
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The minerals have probably been there since the asteroids were formed, but the organic compounds are practically weightless and have probably been blown up there from Earth.
Complex organic compounds of biological origin are chiral (left-handed or right-handed). The Nature paper says that these are racemic or nearly racemic (equal mix of left- and right- handed), which suggests that they are not of terrestrial origin.
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OR (to be fair) they are more than a couple of half-lives of a 100% chiral source with respect to decaying to a 100% racemic mixture.
The origin could be 100% terrestrial L- (or is if D- ? it doesn't matter) material, or it could be 100% alien D- form; you couldn't tell from a racemic mixture.
Those half-lives are strongly temperature dependent, and also moisture level dependent. Once you get below a surface of mineral dust, temperature and water-activi
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Where did they originate?
A 1st generation star went boom.
This released enormous numbers of all the elements starting as a very hot soup where all of these elements are still undergoing various fusions and fissions.
As this very hot soup expands, it cools rapidly, locking the proportions of the various elements down.
During cooling, these elements undergo chemical interactions, molecules forming and breaking apart, before it gets so cold that even chemical interactions no longer take place, locking down the proportions of molec
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if life on Earth was initiated from asteroidal seeding material, that would be an indication that life is more widely spread than just in our system
It is more or less a statistical certainty that life exists through the universe, that's not the question. The question is where did our life originate. It certainly could have originated elsewhere in our solar system than on our own bleak primordial rock. Though I personally would consider it more likely that, yes, that stuff on the asteroid originated right here, I do have to add the caveat that I know fucking nothing about the subject and am perfectly happy to defer to those who do.
Are the chemicals racemic or handed? (Score:2)
If they're racemic, they would struggle to be the source of life as we know it...
Re:Are the chemicals racemic or handed? (Score:4, Insightful)
Thanks (Score:2)
Helpful answer.
Fascinating papers (Score:5, Interesting)
Even just skimming the abstract and beginnings of the two papers is fascinating!
Racemic (even amounts of left- and right- chirality) means not current Earth. More a prehistoric or pre-biological snapshot it seems, since even if the asteroids are from an exploded planet with life on it, presumably that planet would have gone either full-blown left or right chirality, no?
And the second papers notes this is obviously from a *brine*. Which is what you see in the icy plumes, of outer solar system bodies where we think there could be life deep under the surface. Can you get a brine to form just in a comet or asteroid? Sounds iffy but maybe something like a tiny enceladus got knocked about and parts broke off? But far from the asteroid belt it seems.
Not sure what the asteroid's orbit was like but somehow there must be a place where the brine formed and a trajectory to get it to us. Wild!
Re:Fascinating papers (Score:4, Insightful)
Racemic implies a non-biological origin. You'd need radioactive dating to imply a pre-biological origin. I suppose that it's possible some alternative biology could generate only racemic mixes, but it looks quite unlikely (to me). Either a right-handed or a left-handed biology would probably be preferred by evolution. (Either one. I can't think of a reason to choose between them.)
The basic reason the biology would prefer chiral amino acids over racemic is because catalysts often depend on an exact shape match. And biology depends on LOTS of catalysts.
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You'ld need the context of the other materials it was embedded with. That's likely to mean that it can't be done at the moment, but unless you can come up with a better method of dating the stuff...
Even then, since we're talking at the level of molecules, there would probably need to be some fancy justifications. Or lucky embedding in crystals.
But not being able to answer the question doesn't justify jumping at a plausible answer.
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The "non-biological molecule" rests on (particulars depend on which molecule, and I'm no expert in the field) having reasonable non-biological synthetic pathways. Many of them clearly do, but for some I'm not certain. However, when one doesn't need to presuppose a biological origin, then making that supposition is an extra step, and should be avoided.
Now as for why racemic is an indication of non-biological origin, that's because biological reactions are, almost by definition, complex conglomerations of r
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no it doesn't.
If you have a bottle of pure L- (or pure D-) amino acid, and you leave it on a shelf in the chem lab store room for a few years, then measure it's optical activity, you'll see that a considerable amount would have converted spontaneously to the D- (or L-) form. The energy barrier between the two forms is fairly small. How big the energy gap is varies with which (of several hundred) amino acid (or other chiral molecul
Watson/Crick (Score:2)
I always found it interesting that Francis Crick (of "Watson & Crick" fame, discoverers of the double helix structure of DNA) was interested in the idea of directed panspermia. Decent article on the idea here https://retrospectjournal.com/... [retrospectjournal.com]
Personally, from a very limited look at all the extremophiles/bacteria/microbes we've got on our planet, I'd be very suprised if the entire universe isn't crawling with life.
Intelligent life on the other hand... Judging by the state of our planet I'd say that's goi
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I'm not sure about the "directed" part, but I do think panspermia is worth careful consideration. If life starts anywhere, some of it is likely to be spalled off into space via impacts. And this could be an amplification-via-recursion phenomenon. The only question is "How long could it survive in transit?", but cold is a great preservative. (OTOH, panspermia may be a bit too inclusive. But life might spread this way throughout a star cluster and into systems that pass nearby.)
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Which is a subject very amenable to experiment. A million or several years is feasible. A billion ... much harder.
Would it travel this way faster than the random production of life from non-life in a geological context? We know that our one actual example of life achieved that in around a billion years form "scratch", so you'd need to achieve a "transport" e
Andromeda Strain (Score:2)
but its the lifeforms from space that don't contain Amino Acids that you have to worry about.
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Which says nothing about what it uses for a "hereditary information" molecule. Precisely "nothing", not approximately "nothing."
As for the chemistry of it's cell walls - lots of plausible molecules; only a handful of which are anything like common in Earthly life.
Personally, every time I look at the phase diagram of water-CO2-NH3, I see several eutectics and think of the thermodynamic and biochem
Supreme Court just announced (Score:2)
Do over coming in 2032 (Score:2)
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Various gods on the other hand have highly trumpeted "second comings" most months, and not once have they come true.
At 60-some m diameter, it's capable of around 10 times the damage of the 2013 Chelyabinsk impactor
ho hum (Score:2)
There is nothing new about finding amino acids in asteroids or meteorites. Calling them "building blocks of life" is a stretch.
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