Are these building blocks not evaporated on impact?
Only the outer surface of asteroids gets hot. Atmospheric entry isn’t long enough to thoroughly cook a rock.
Ryugu asteroid samples contain all DNA and RNA building blocks
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Re: Ryugu asteroid samples contain all DNA and RNA building blocks
#42One longstanding theory is that life first began on Earth when asteroids carrying fundamental elements crashed into our planet long ago. I'm no expert but this sounds strange. Surely those fundamental elements would also form in vast quantities on their own on an entire planet with volcanoes and oceans? Wouldn't a couple asteroids be the literal drop in the ocean in comparison? The missing part is how do they form se…
This theory is called panspermia [1] and it has several alternatives. One of the most extreme is that in the very early Universe, these building blocks could spread easily because the ambient temperature of the Universe was significantly higher than it is now. This isn't the most popular version.
The most popular is that asteroids and other interstellar bodies spread the building blocks, be it anywhere from amino acids to more complex building blocks. As evidence of this, there are hundreds of surviving asteroids on Earth that have been positively identified as having coming from Mars, which is pretty crazy because that basically takes a violent impact throwing debris into space and it making it to us many times over.
Part of the evidence for all this is how soon after the Earth formed that life appeared. We have positive evidence that this only took a few hundred million years. That's kinda crazy if you think about it. Also consider that the oceans likely came after the EArth formed.
Our galaxy is over 10 billion years old. The Sun is less than 5 billion years old. So that's 5+ billion years for stars and Solar Systems to form, evolve and die before the first fusion reaction in the Sun. Some of this needed to happen just to form heavy elements that are relatively abundant. Even that's kind of crazy. Heavy elements like lead, uranium and gold take relatively rare and violent events to eject material into space and make it to us. So what else made it to us?
Re: Ryugu asteroid samples contain all DNA and RNA building blocks
#43Earlier quoted context omitted.
I guess it depends on how you define life, and whether we'd even recognize it when we see it, assuming we're looking in the right places. I'd also imagine that any type of chemistry that harvests energy from the environment is liable to find itself as a food source at the bottom of the food chain now that earth is teeming with life. I think that self-replication, and ability to harvest chemicals and energy from the e…
read up on the RNA world theory, it's so cool
Have you seen this MLST interview of Blaise Aguera ?
https://www.youtube.com/watch?v=rMSEqJ_4EBk
He's an interesting person overall - the long interview is well worth watching if you haven't already seen it - but the relevance here are his experiments with the emergence of self-replicating computer programs out of random components.
His starting point is entire "programs" (random sequences of 64 characters, of which only ~7 have any meaning - the program "statements" of the BF language), so perhaps more suggestive of this RNA world stage, but perhaps also of what came before it when there may have been collectively self-replicating soups consisting of discrete components rather then entire structural encodings.
Re: Ryugu asteroid samples contain all DNA and RNA building blocks
#44Re: Ryugu asteroid samples contain all DNA and RNA building blocks
#45One longstanding theory is that life first began on Earth when asteroids carrying fundamental elements crashed into our planet long ago. I'm no expert but this sounds strange. Surely those fundamental elements would also form in vast quantities on their own on an entire planet with volcanoes and oceans? Wouldn't a couple asteroids be the literal drop in the ocean in comparison? The missing part is how do they form se…
The major flaw in Panspermia is that it all had to start somewhere without Panspermia. If it did that there, why not here?
Re: Ryugu asteroid samples contain all DNA and RNA building blocks
#46Earlier quoted context omitted.
We could artificially create a sterile, large pool of the ingredients and see what happens. I've read about experiments like this but only at lab beaker scale.
It's funny talking about non software stuff on HN. I'm sure there's hundreds of papers on simulations and expert analysis of this.
Then please link the best ones? Or write some of your high-level thoughts about it.
You don't need to be an expert to be curious. Many here would surely like to know more. That's why non-IT stories are upvoted in the first place.
Re: Ryugu asteroid samples contain all DNA and RNA building blocks
#47Earlier quoted context omitted.
Huh? Those smaller rocks would be even more irradiated, as they have no atmosphere? They’d also have to contend with re-entry.
The smaller rocks are composed of those materials in solid state (e.g., ice not water). They are less irradiated as they are further away from the Sun (think the asteroid belt and beyond). Atmospheric entry (if that's what you mean) is irrelevant. What matters here is the transport of materials from a place where they could have formed, to a place where they couldn't.
> Atmospheric entry (if that's what you mean) is irrelevant.
I think the OP meant that Earths magnetic field and atmosphere shields any terrestrial matter far more than than a bare asteroid that has no such protections, so it seems implausible at first glance that these things would develop or survive in open space rather than here.
Re: Ryugu asteroid samples contain all DNA and RNA building blocks
#48Earlier quoted context omitted.
The timing of the delivery is what's important here. These building blocks, organic matter, and water would have been depleted in the proto-Earth due to Solar irradiation. There needs to be some mechanism that delivers these ingredients from the outer Solar System. Bombardment by smaller rocks makes the most sense, and was likely triggered by the migration of Giant Planets, leading to a period of heavy bombardment (o…
Huh? Those smaller rocks would be even more irradiated, as they have no atmosphere? They’d also have to contend with re-entry.
Those smaller rocks are in the outer solar system, where the solar irradiation is lower. But the way they are composed is lots of ices (volatile molecules in solid form) being built on the silicate/graphite refractory core. The ices remain preserved in the environment provided by the outer solar system.
Re: Ryugu asteroid samples contain all DNA and RNA building blocks
#49Earlier quoted context omitted.
The timing of the delivery is what's important here. These building blocks, organic matter, and water would have been depleted in the proto-Earth due to Solar irradiation. There needs to be some mechanism that delivers these ingredients from the outer Solar System. Bombardment by smaller rocks makes the most sense, and was likely triggered by the migration of Giant Planets, leading to a period of heavy bombardment (o…
Huh? Those smaller rocks would be even more irradiated, as they have no atmosphere? They’d also have to contend with re-entry.
It would’ve been specifically asteroids from beyond the "frost line", where it’s cold enough for volatile substances to coalesce and stay solid.
Re: Ryugu asteroid samples contain all DNA and RNA building blocks
#50One longstanding theory is that life first began on Earth when asteroids carrying fundamental elements crashed into our planet long ago. I'm no expert but this sounds strange. Surely those fundamental elements would also form in vast quantities on their own on an entire planet with volcanoes and oceans? Wouldn't a couple asteroids be the literal drop in the ocean in comparison? The missing part is how do they form se…
Why are you assuming couple of asteroids? Life first appeared 3.5 billion years ago. The frequency of an asteroid impact on Earth is ~500,000 years.