Ryugu asteroid samples contain all DNA and RNA building blocks

(phys.org)

36 points by bookofjoe1 hour ago

7 comments

0x000xca0xfe1 hour ago
<pre><code> One longstanding theory is that life first began on Earth when asteroids carrying fundamental elements crashed into our planet long ago. </code></pre> 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 self-replicating mechanisms capable of evolution. I doubt an asteroid with a bit of organic dust is enough for that. If such small amounts suffice we should see the formation of new life forms from scratch, today, left and right I think?
- HarHarVeryFunny39 minutes ago
 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 environment to make more of what you're built of, is the point of complexification of chemistry that is best considered as the most primitive form of life. From there you can go on to things that are capable of encoding structure and more complex chemical factories.I suppose one signature of these earliest type of "emergent life" chemistries would be localized concentrations of things like these nucleobases that we know are the building blocks of life as we know it, but there may be other types of self-replicating chemistries that emerge too, that don't lead anywhere.
- _joel22 minutes ago
 <a href="https://en.wikipedia.org/wiki/Late_Heavy_Bombardment" rel="nofollow">https://en.wikipedia.org/wiki/Late_Heavy_Bombardment</a> - possibly?
- starburst1 hour ago
 Well the competition might be too fierce for any new life to develop
 - 0x000xca0xfe56 minutes ago
 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.
 - pixl9728 minutes ago
 The bigger the pool the harder to create it here on Earth without introducing problems. For example, take a prion. Hard as hell to actually get rid of, how do you know you've not actually introduced something like this to your sterile pool that's going to make it do things you don't expect.
 - HarHarVeryFunny14 minutes ago
 I don't think you'd want a single homogeneous "large pool", but rather a large variety of different types of micro-environment, including all those that have been suggested as possible environments for the emergence of life - the chemical and physical environments of hydrothermal vents, volcanic hot springs, shorelines, different types of rocks, clays, etc. You'd want to have environments that included all energy sources present on earth (solar, lightening, geothermal), all forms of mechanical agitation/mixing (hydrothermal, waves), etc, etc.
 - HarHarVeryFunny23 minutes ago
 Yeah, but it seems impossible to experiment on the scale that would have happened in nature where there would have been millions of localized "test tube experiments" ongoing for millions of years.Of course people can, and do, try to replicate early earth environments and self-assembling proto-cells, but I'm not sure how intellectually satisfying any self-replication success from these "designer experiments" would be, unless perhaps done on such large scale (simulation vs test tube?) that any conclusions could be made about what likely happened in nature - just how specific do the conditions need to be?
 - 0x000xca0xfe6 minutes ago
 My personal theory is that the conditions for life are plentiful in the universe but it probably took an unbelieavable number of random chemical/mechanical events to form the first proto-lifeform.<pre><code> The discovery comes after these building blocks of life were detected on another asteroid called Bennu, suggesting they are abundant throughout the solar system. </code></pre> Yet actual life remains to be discovered...
 - moralestapia4 minutes ago
 Does 'we' include 'you'?
- ToucanLoucan15 minutes ago
 Admittedly, am layman, have only heard numerous sciencey folks talk about it, but we've found all these basic components in space already, naturally occurring, and while we've never to my knowledge recreated actual, genuine abiogenesis, we have observed every process required for abiogenesis to be a reasonable explanation for the origin of life.As to your question on we should see the formation of new life everywhere, well, if we looked hard enough we might? The answer is competitive exclusion. Abiogenesis would've occurred on a remarkably clean earth: any life now emerging from the proverbial space dust is both almost certainly not preconfigured for this biosphere, and is instantly drowning in competing microorganisms that are. Anything that does form is likely quickly killed either by natural forces or competing organisms. Meanwhile, our life goes everywhere: We've found living bacteria on the outside of the ISS!
johnsmalles19 minutes ago
Fascinating that all five nucleobases were found in Ryugu samples. The fact that these formed abiotically in an asteroid environment strengthens the case that the building blocks of life are common throughout the solar system. The amino acid findings from the same samples were already compelling, but having the complete nucleobase set is a different level of evidence.
fusslo1 hour ago
I wonder how they prevent contamination of the containers used to collect and store samples.I assume they have to be ultra clean in every sense of the word 'clean' with the cavity pulled to a vacuum. And also the equipment that collects the sample and puts it into the canister has to be clean as well.The logistics aren't obvious to me at all
- ceejayoz59 minutes ago
 They seem pretty confident. There's been some conflicting reporting on contamination of the Ryugu samples over time.<a href="https://phys.org/news/2024-11-ryugu-asteroid-sample-rapidly-colonized.html" rel="nofollow">https://phys.org/news/2024-11-ryugu-asteroid-sample-rapidly-...</a>> Researchers from Imperial College London have discovered that a space-returned sample from asteroid Ryugu was rapidly colonized by terrestrial microorganisms, even under stringent contamination control measures.<a href="https://www.isas.jaxa.jp/en/topics/003899.html" rel="nofollow">https://www.isas.jaxa.jp/en/topics/003899.html</a>> As described in the discussion of the journal paper, all samples received from JAXA have undergone the initial description, storage, and sealing in dedicated containers under a nitrogen atmosphere. The samples are distributed to researchers without exposure to the Earth's atmosphere. The possibility of microbial contamination is therefore considered extremely low. In addition, organic and microbial contamination assessment of the environment at the curation facilities within JAXA (clean chamber) in which the Ryugu sample grains undergo the initial description are conducted 1 ~ 2 times a year. It has been confirmed and reported that the concentration of organic matter is at or below the same level as that of the OSIRIS-REx asteroid return sample glove box at the NASA Johnson Space Center, and that no microbial colonies have been detected in the microbial contamination assessment conducted with swabbing and culture medium (Yada et al., 2023). Based on these facts, we agree that the microbial contamination described in the paper did not occur during a process within JAXA, but under the laboratory environment of the allocated researchers.
 - fusslo28 minutes ago
 ty ty! I usually just give a quick chatgpt buy my work blocked every ai but copilot
- bookofjoe57 minutes ago
 <a href="https://science.gsfc.nasa.gov/sed/content/uploadFiles/publication_files/Naraoka%202023.pdf" rel="nofollow">https://science.gsfc.nasa.gov/sed/content/uploadFiles/public...</a>
 - fusslo29 minutes ago
 you're the reason why I love HN.
pfdietz1 hour ago
It contains nucleobases. But does it contain ribose, or ribose linked to the nucleobases, or to phosphates? And more generally, does it also contain a grab bag of related chemicals that are not building blocks? The existence of such blocks as minor constituents of a soup of random chemicals doesn't mean much, especially as the concentration of any such constituent declines exponentially with its complexity.
- ceejayoz1 hour ago
 <a href="https://www.nasa.gov/missions/osiris-rex/sugars-gum-stardust-found-in-nasas-asteroid-bennu-samples/" rel="nofollow">https://www.nasa.gov/missions/osiris-rex/sugars-gum-stardust...</a>> The five-carbon sugar ribose and, for the first time in an extraterrestrial sample, six-carbon glucose were found.The soup does matter, as does finding that the ingredients are everywhere.
 - pfdietz1 hour ago
 Finding exponentially decreasing amounts of specific chemicals is about as informative as finding short words in strings of random letters.
 - ceejayoz58 minutes ago
 Finding short words in strings of random letters at least establishes the existence of letters and words.It doesn't demonstrate the existence of Shakespeare's works, but it's a building block that's good to know exists.
 - pfdietz54 minutes ago
 All it means is you can say "if life is rare, it's not because these specific small chemicals can't be produced". Which is a rather weak thing to say. It doesn't imply life isn't rare, or that further advancement the existence of these small building blocks is easy or inevitable.
 pixl9724 minutes ago
 Finding strong things here is going to be difficult. Sometimes you have to take a bunch of weak things to figure out where they lie for guidance.
 ceejayoz49 minutes ago
 > All it means is you can say "if life is rare, it's not because these specific small chemicals can't be produced".This is absolutely a good finding to have in your pocket.
- HarHarVeryFunny57 minutes ago
 It's a sample of one, but I think the takeaway is just that if the nucleobases are present on a random asteroid then they probably commonly occur. Of course as you note it takes a lot more than that to form these into nucleic acids.I would guess there is a more primitive stage in the emergence of life where self-replicating soups (Kaufmann: metabolisms), including things like nucleobases and amino acids, capable of collective replication/expansion exist, before we get anything as sophisticated as nucleic acids and structural encoding.
_ink_37 minutes ago
Are these building blocks not evaporated on impact?
hmokiguess1 hour ago
How are samples collected? In space or as debris?
- sheikhnbake1 hour ago
 Surface sample: Hayabusa2's sampling device is based on Hayabusa's. The first surface sample retrieval was conducted on 21 February 2019, which began with the spacecraft's descent, approaching the surface of the asteroid. When the sampler horn attached to Hayabusa2's underside touched the surface, a 5 g (0.18 oz) tantalum projectile (bullet) was fired at 300 m/s (980 ft/s) into the surface.[72] The resulting ejected materials were collected by a "catcher" at the top of the horn, which the ejecta reached under their own momentum under microgravity conditions.Sub-Surface Sample: The sub-surface sample collection required an impactor to create a crater in order to retrieve material under the surface, not subjected to space weathering. This required removing a large volume of surface material with a powerful impactor. For this purpose, Hayabusa2 deployed on 5 April 2019 a free-flying gun with one "bullet", called the Small Carry-on Impactor (SCI); the system contained a 2.5 kg (5.5 lb) copper projectile, shot onto the surface with an explosive propellant charge. Following SCI deployment, Hayabusa2 also left behind a deployable camera (DCAM3)[Note 1] to observe and map the precise location of the SCI impact, while the orbiter maneuvered to the far side of the asteroid to avoid being hit by debris from the impact.It was expected that the SCI deployment would induce seismic shaking of the asteroid, a process considered important in the resurfacing of small airless bodies. However, post-impact images from the spacecraft revealed that little shaking had occurred, indicating the asteroid was significantly less cohesive than was expected.[76]Duration: 36 seconds.0:36 The touchdown on and sampling of Ryugu on 11 July Approximately 40 minutes after separation, when the spacecraft was at a safe distance, the impactor was fired into the asteroid surface by detonating a 4.5 kg (9.9 lb) shaped charge of plasticized HMX for acceleration.[56][77] The copper impactor was shot onto the surface from an altitude of about 500 m (1,600 ft) and it excavated a crater of about 10 m (33 ft) in diameter, exposing pristine material.[15][32] The next step was the deployment on 4 June 2019 of a reflective target marker in the area near the crater to assist with navigation and descent.[33] The touchdown and sampling took place on 11 July 2019.[34]<a href="https://en.wikipedia.org/wiki/Hayabusa2#Sampling" rel="nofollow">https://en.wikipedia.org/wiki/Hayabusa2#Sampling</a>
zenon_paradox1 hour ago
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