The country may be swirling down the drain, but at least we’ve got some interesting news from outer space…even if Nature chose a really misleading title for their article, Asteroid fragments upend theory of how life on Earth bloomed. Scientists are analyzing the samples returned from a probe sent to the asteroid Bennu. They’ve found all 5 nucleic acid bases, and 14 of our familiar 20 amino acids, which is not surprising. We’ve found those in meteorites here on Earth.
Furthermore, the molecules are found in roughly equal numbers of right- vs. left-handed enantiomers, which is also not surprising. It’s biological synthesis that favors one handedness over the other; this is exactly what we’d expect of molecules built via inorganic synthesis in a lifeless rock. We might have to upend a few theories if these molecules were found to have been assembled by living organisms that had been living on an ancient space rock. But they weren’t, so nobody is rewriting any biology textbooks.
I did not expect this, though:
In an accompanying paper published in Nature today, other researchers report that the material from Bennu is also rich in salts created billions of years ago, probably when watery ponds on Bennu’s parent asteroid evaporated and left behind a crust of minerals. Although no signs of life were spotted on Bennu, those salty ponds would have been a good environment to foster the chemistry that could lead to it.
Salty ponds? On space rocks? I’d like to know more about that, although note that there’s no evidence that life evolved in puddles on asteroids. It’s still cool to imagine briny ponds on distant moons and planetoids.
Could Bennu have been ejected in a collision from some parent body large enough to have retained an atmosphere with high enough pressure for liquid water to exist?
Or is that scenario even plausible for a rubble pile?
So a hypothesis could be the conditions are appropriate for nucleotides as the end product of geochemistry and hydrochemistry. Cells just had to figure out how to do the steps on their own but by bit.
I’m still ignoring extraterrestrial water because that just comes out of the magmatic vents and volcanoes and… it’s the most common element (H) in the universe and a very reactive element that is the most common in the crust (O).
From the referenced paper:
“These include sodium-bearing phosphates and sodium-rich carbonates, sulfates, chlorides and fluorides formed during evaporation of a late-stage brine that existed early in the history of Bennu’s parent body. Discovery of diverse salts would not be possible without mission sample return and careful curation and storage, because these decompose with prolonged exposure to Earth’s atmosphere. Similar brines probably still occur in the interior of icy bodies Ceres and Enceladus, as indicated by spectra or measurement of sodium carbonate on the surface or in plumes.”
(Kinda big bodies, those)
—
Also, a stone soup reference? Heh.
(And, of course, essential salts)
No ribose was detected from what I have found. Just the bases.
I found this though.
https://www.nasa.gov/news-release/first-detection-of-sugars-in-meteorites-gives-clues-to-origin-of-life/
Now what were/are the conditions that select ribose as a stopping point?
My guess is the parent body was probably some hundreds of kilometers across and had substantial amounts of water mixed in the primordial rock material. Interior temperature and pressure were suitable for liquid water. As the body became differentiated, water was squeezed to the surface, forming a partially frozen ocean that evaporated after a while. Later on, some of the remnant salty groundwater might emerge as geysers, evaporating immediately.
I guess an RNA creature like a preribosome would consider environmental glycine as food. Glycine has no stereoisomers. Would the life have used the mixed isomers while learning to make a specific one with associated chemical and structural predictability?
I wodner how typical or otherwise Bennu is.
Call me greedy but would be wonderful to have samples froma lot mroe asterpoids to compare it with.
Of course, we don’t know “why” life uses only one chiral form, though one suggestion has been that there are magnetic properties to some chemicals, which could “skew” the odds in favor of one over the other, among others. But, yeah, starting with a 50/50 mix makes sense, its just, “Why did then one version take over, compared to the other.”
Network externalities. Once you start using one chirality, everything works better if you stick to it from then on. That in turn is a recipe for spontaneous symmetry breaking. Some early life form picked a chirality and stuck with it, and was lucky enough that everything extant now on Earth descended from that one. But the initial choice was as arbitrary as driving on the right.
@ ^ Bekenstein Bound : Some places drive on the other side of the road. We drive on the left hand side here in Oz. So applying that to that analogy seems no reason other lifeforms might have evolved having picked and stuck to the other chirality right? Or would that be pushing the analogy too far?
StevoR, “So applying that to that analogy seems no reason other lifeforms might have evolved having picked and stuck to the other chirality right?”
It kind of does. Think about it.
Chiral catalysts or templates can surely induce the formation of one enantiomer over another.
(At that point, the dice have been thrown)
—
Think Betamax vs VHS as an allegory. Convenience wins.
(Ref for you; not for just anyone, but i respect you: https://en.wikipedia.org/wiki/Videotape_format_war )
@ ^ John Morales : Thanks.
[meta]
StevoR, sorry, circumstances mean I’m a bit maudlin.
Anyway, I know of no more genuine commenter, no more well-meaning a person than you.
(I do not lie)
@ ^
lol.
Does this mean you’re taking back calling Stevo a “puppy”, or are you saying being genuine and well-meaning are characteristics of puppies?
Perhaps. But if the first replicator quickly spread, ate all the remaining yummy carbon molecule precursors to life, and then its descendants started eating other fast enough, a second independent one might not have had time to arise before its ingredients got snarfed up.
What we can be certain of is this: any such alt-handed paleolife seems to have gone extinct without making it to the present. This might be down to luck of the draw, with an our-handed LUCA living near some deep black smoker environment surviving the Late Heavy Bombardment down there while everything more exposed got culled.
I don’t think that’s quite the right word for it. Maudlin is, like, sad and moping and stuff, often because you’re grieving someone or something (a certain dead 249-year-old republic would be an obvious suspect here). What you are is bellicose, belittling, and brusque, which is generally associated with anger, drunkenness, or just generally being a dick, but usually in turn is hiding deep insecurities or social fears, or else is a lashing out borne of frustration about something elsewhere.
“I don’t think that’s quite the right word for it.”
Ah well. I can live with that.
—
“What you are is bellicose, belittling, and brusque, which is generally associated with anger, drunkenness, or just generally being a dick, but usually in turn is hiding deep insecurities or social fears, or else is a lashing out borne of frustration about something elsewhere.”
Lovely.
Bekenstein Bound @15: Anyone, except perhaps a sociopath, can be rendered maudlin by circumstances. And your diagnosis is worth every penny that was paid for it.
Nature astronomy mentions amino acids and nucleotide bases…”along with ~10000 N-bearing chemical species”. It would be interesting to know if they’re actually a significant component, or if we are just singling out the things that life happens to use out of a sludge where pretty much every possible organic compound occurs.
I didn’t claim that he was incapable of ever being maudlin. I claimed, and I stand by that claim, that his observable behavior looks like something very different at this time.
[OT + personal]
BB, my younger sister is being treated for Stage3a small cell carcinoma of the cervix. Never smoked, never did drugs, never boozed much. Exercised. Was normal. One of the very few people to get a certificate from the Real Academia Española in Spanish.
Taught English in France, and in Saudi Arabia. Came home to look after my ailing mum and basically destroyed her career.
But she had not had a smear for a dozen years, so by the time the symptoms became evident, it was a bit late. Currently, has lost 12Kg (she is an ethical ovo-vegetarian, but only from chickens such as mine) and her hair is falling out and whatnot. And the rest of it.
My wife’s friend’s relative just perished from a stroke. She took the day off yesterday to drive her friend to the hospital for a final visit.
Other stuff. You know, so, yeah. That was my mood then.
(Now, I’m getting irritated by you)
And, may I say, it sure seems fucking nasty to me the way the commenter using the nym “Silentbob” pops in whenever I try to be nice to someone and spills some spite. I remember multiple occasions.
(Malice, I can see it plain as)
@ 3 Morales
Kinda not. Ceres is a quarter the size of the moon, Enceladus one seventh (diameter wise).
@ ^ Silentbob : Size is of course relative. Both Ceres and Enceladus are big enough to be gravitationally self-rounded and geologically differentiated and active. So “kinda big” indeed that term obvs being a subjective one. Big enough to have enough water and activity to be potential, possible homes for life.
(sigh)
https://science.nasa.gov/dwarf-planets/ceres/facts/
“Dwarf planet Ceres is the largest object in the asteroid belt between Mars and Jupiter, and it’s the only dwarf planet located in the inner solar system. It was the first member of the asteroid belt to be discovered when Giuseppe Piazzi spotted it in 1801. When NASA’s Dawn arrived in 2015, Ceres became the first dwarf planet to receive a visit from a spacecraft.
Called an asteroid for many years, Ceres is so much bigger and so different from its rocky neighbors that scientists classified it as a dwarf planet in 2006. Even though Ceres comprises 25% of the asteroid belt’s total mass, Pluto is still 14 times more massive.”
Not big, in your estimation, Silentbob.
https://en.wikipedia.org/wiki/Ceres_(dwarf_planet)
9.3839×10^20 kg
A phase diagram of water shows you would need at least 0.06 atmosphere of atmospheric pressure to have standing water in a pool on the surface of a body.
For comparison the surface pressure of the Moon is ~3 x 10^-15 atmosphere, or on Io (same size as the moon but volcanically active) 0.3 to 3 x 10^-9 atmosphere.
(for those unfamiliar with scientific notation, 10^-x means you move the decimal point x digits to the left; i.e. 3 x 10^-9 = 0.000000003)
Earth is the only body in our solar system capable of having standing pools of water on the surface. Saturn’s moon Titan has a thicker atmosphere and plenty of water but is far too cold for that water to be liquid. Enceladus is hypothesised to have a subsurface ocean because of tidal heating by its parent body Jupiter, but the surface is ice.
PS. I’m sure you are aware of the potential life and geysers and “tiger stripes” (Sulci) of Enceladus but when it comes to Ceres note :
Source : https://www.astronomy.com/science/ceres-an-ocean-world-in-the-asteroid-belt/
(1 atmosphere is, of course, the Earth surface atmospheric pressure we’re used to.)
@25.Silentbob : Earth is the only body in our solar system capable of having standing pools of water on the surface.
In their current orbits and at this moment in the history of our solar system yes.
Both Venus and Mars may have – indeed, very probably did have – oceans, lakes and rivers previously billions of years earlier in our solar systems history and if you shift some of the larger worlds both moons and ice dwarfs alike into the inner solar stystem it seems quite possible many even most of they could have standing water or even become water worlds now. It is quite likely that as our daytime star evolve and balloons out into a red giant these worlds will become water worlds albeit breifly too.
Correction: Enceladus is a moon of Saturn, not Jupiter. X-D
C’est dommage.
“Earth is the only body in our solar system capable of having standing pools of water on the surface.”
Dang! If only the authors of the featured paper had known that!
[c’est la vie]
@5. lumipuna
Seems quite likely to me although there’s another possibility if the idea noted here – Could Our Earth Be The Product Of A Planetary Demolition Derby? where our inner solar system planets are second generation planets having formed in a depleted region after the first inner solar system worlds including super-Earth’s that smashed together or fell into the sun as Jupiter migrated inwards then outwards again is correct. Maybe, just maybe, the material that now makes up Bennu was once part of a super-earth or other former first generation planet that formed at the very dawn of our solar system but was since destroyed? Speculative and probly not but still..