[HN Gopher] Ryugu asteroid samples contain all DNA and RNA build...
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Ryugu asteroid samples contain all DNA and RNA building blocks
Author : bookofjoe
Score : 158 points
Date : 2026-03-17 12:01 UTC (10 hours ago)
(HTM) web link (phys.org)
(TXT) w3m dump (phys.org)
| pfdietz wrote:
| 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.
| ceejayoz wrote:
| https://www.nasa.gov/missions/osiris-rex/sugars-gum-stardust...
|
| > 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.
| pfdietz wrote:
| Finding exponentially decreasing amounts of specific
| chemicals is about as informative as finding short words in
| strings of random letters.
| ceejayoz wrote:
| 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.
| pfdietz wrote:
| 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.
| ceejayoz wrote:
| > 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.
| pfdietz wrote:
| "Good"? Ok, if it makes you feel better. But
| scientifically, it doesn't do much.
| pixl97 wrote:
| 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.
| HarHarVeryFunny wrote:
| 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.
| kjkjadksj wrote:
| The nucleobases can self polymerize into nucleic acids
| hmokiguess wrote:
| How are samples collected? In space or as debris?
| sheikhnbake wrote:
| 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]
|
| https://en.wikipedia.org/wiki/Hayabusa2#Sampling
| mkl wrote:
| From near the start of the article: "In 2014, the Japanese
| spacecraft Hayabusa-2 blasted off on a 300-million-kilometer
| (185-million-mile) mission to land on Ryugu, a 900-meter-wide
| (2,950-feet-wide) asteroid. It successfully managed to collect
| two samples of rocks weighing 5.4 grams (under a fifth of an
| ounce) each and bring them back to Earth in 2020."
| 0x000xca0xfe wrote:
| One 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 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?
| starburst wrote:
| Well the competition might be too fierce for any new life to
| develop
| 0x000xca0xfe wrote:
| 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.
| pixl97 wrote:
| 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.
| HarHarVeryFunny wrote:
| 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 a 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?
| 0x000xca0xfe wrote:
| 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. The
| discovery comes after these building blocks of life were
| detected on another asteroid called Bennu, suggesting
| they are abundant throughout the solar system.
|
| Yet actual life remains to be discovered...
| HarHarVeryFunny wrote:
| > Yet actual life remains to be discovered...
|
| We've barely started to look, other than on Mars, and
| notably we are seeing possible signs there. There may
| even still be primitive life there.
|
| If we do find life of Mars, or say Europa, i.e. in the
| very first places we look for it, that that would be
| highly suggestive that it is extremely common (at least
| in primitive form).
| edgyquant wrote:
| Also it seems that finding a balance where an ecosystem
| doesn't kill itself with its own waste is probably harder
| than we assume. Earth life has totally changed the
| atmosphere of the planet, I would many it many cases even
| when life does for it kills itself early on
| HarHarVeryFunny wrote:
| 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.
| moralestapia wrote:
| Does 'we' include 'you'?
| make3 wrote:
| 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.
| 0x000xca0xfe wrote:
| 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.
| freedomben wrote:
| Surely in a minority, but I do see posts from people on
| HN that are scientists, researchers, even mechanics and
| such. We definitely get a lot of speculation, but I've
| learned never to underestimate the level of expertise of
| people in our community.
| sph wrote:
| The biology equivalent of "infinite monkeys at a
| typewriter"
| HarHarVeryFunny wrote:
| 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.
| make3 wrote:
| read up on the RNA world theory, it's so cool
| HarHarVeryFunny wrote:
| 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.
| adrian_b wrote:
| Parts of the RNA world theory are correct, but other parts
| are completely bogus and completely illogical.
|
| What is correct is that RNA must have existed a very long
| time before DNA, during which RNA was the only nucleic
| acid.
|
| Moreover, self-replicating RNA must have existed before
| ribosomes and proteins (where "protein" means a polypeptide
| that is synthesized using a RNA template).
|
| It should be obvious that neither ribosomes nor protein-
| encoding RNA-sequences may exist before the existence of
| self-replicating RNA, because the living being in which
| those would exist would immediately die without
| descendants, together with its content of ribosomes and
| proteins.
|
| So far so good, but some of the supporters of the RNA World
| theory claim that before the existence of protein-based
| enzymes, all chemical reactions inside a living being must
| have been catalyzed by RNA molecules.
|
| This is an illogical claim, which is false beyond any
| reasonable doubt. Some RNA-based catalysts may have existed
| quite early, and some still exist today. However, any RNA-
| based catalyst could have appeared only at a later time
| after the establishment of RNA self-replication. The
| argument is the same as for protein-based catalysts, any
| living being with a RNA catalyst, but without RNA
| replication would die and the RNA catalyst would disappear
| without descendants.
|
| So there is no doubt that the first feature of RNA that has
| appeared was self-replication, and at that time RNA could
| not have any other role inside a living being, because any
| such role would not have been inherited.
|
| In other words, the first self-replicating RNA molecules
| were a kind of RNA virus, which multiplied inside the
| existing living beings, consuming energy and substances,
| without providing benefits. Only later, when eventually RNA
| templates have become the main method for synthesizing the
| useful components of a living being, something akin to a
| symbiosis between RNA and the rest of the living being was
| achieved, arriving to the structure of life that is known
| today.
|
| For the first self-replicating RNA molecule to appear, the
| living beings must have contained abundant ATP and the
| other nucleotides. So the original role of the nucleobases
| in living beings was not the storage of information, but
| the storage of the energy required for synthesizing organic
| polymers. The self-polimerization of the nucleotides, which
| forms RNA, was an unwanted side reaction. In other words,
| before the RNA world, there already was an ATP world, which
| was the first user of nucleobases.
|
| If RNA could not have been the material for making enzymes
| before the proteins, such enzymes must have been made from
| peptides (i.e. polymers of amino-acids), exactly like the
| enzymes of today, but those peptides must have not been
| synthesized using ribosomes, like the proteins. Such
| peptides still exist today and they remain widespread in
| all living beings, and they are named non-ribosomal
| peptides. Their mechanisms of synthesis are much less
| understood than the mechanisms of RNA-based protein
| synthesis. It is likely that more research into non-
| ribosomal peptides might provide a better understanding of
| how a living being without RNA could function.
|
| In order to have a self-replicating living being you do not
| need a self-replicating molecule able to store arbitrary
| information, like RNA. It is enough to have a chain of
| synthesis reactions that closes a positive-feedback cycle,
| i.e. the products of one reaction are reactants for the
| next reaction and the products of the last reaction are the
| reactants for the first. If the chain of reactions produces
| all the components of a living being, growth and self-
| replication can be achieved.
|
| The defect of such a living being is that evolution is
| extremely difficult. any mutation in one of the catalysts
| used in the chain of reactions is more likely to break the
| positive feedback and lead to death, instead of producing
| an improved living being. After the appearance of memory
| molecules, i.e. RNA and later DNA, which can store the
| recipe for making an arbitrary polymer molecule, it became
| possible to explore by mutations a much greater space of
| solutions, leading to a greatly accelerated evolution of
| the living beings.
| gus_massa wrote:
| I read a few times your comment and I went from " _Nah_ "
| to " _It makes a lot of sense_ ". I'm adding the " _ATP
| word_ " to my list of interesting ideas.
|
| Some related stuff:
|
| * https://www.science.org/doi/10.1126/science.adt2760
| They made RNA that copies itself, but it use as a
| starting point activated triplets of bases. i.e, if ATP
| is AR-PPP, they use a mix of something compounds like AR-
| P-AR-P-AR-PPP that stil have the triphosphate to store
| energy and be easy to link, but already have tree linked
| bases. This is even more difficult that a soup of ATP and
| friends.
|
| * https://en.wikipedia.org/wiki/PAH_world_hypothesis The
| idea is that before the RNA word, there was something
| simpler, like this. Is it possible to use ATP to build
| more PAH? I also remember about a version of RNA that
| instead of ribose it used something smaller (glicerol?),
| but I can't find it.
| majkinetor wrote:
| > 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
|
| Once there are forms that harvest and self-replicate,
| however, its expectable that there will be forms that
| delegate those features to others, like viruses. Cellular
| machinery that is required to implement those feature is not
| free, so parasitic forms would have survival advantage.
| _joel wrote:
| https://en.wikipedia.org/wiki/Late_Heavy_Bombardment -
| possibly?
| pfdietz wrote:
| There is some skepticism now that the LHB was real.
|
| https://www.youtube.com/watch?v=IZfzbEtKF9o
| ToucanLoucan wrote:
| 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!
| BinaryAsteroid wrote:
| 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 (on a bare
| Earth -- no oceans, no volcanoes)..
| https://en.wikipedia.org/wiki/Nice_model
| lazide wrote:
| Huh? Those smaller rocks would be even more irradiated, as
| they have no atmosphere?
|
| They'd also have to contend with re-entry.
| BinaryAsteroid wrote:
| 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.
| naasking wrote:
| > 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.
| adrian_b wrote:
| Atmospheric entry is completely relevant because some
| people have made the illogical claim that meteorites
| falling on Earth could have contributed with such complex
| organic substances, like the nucleobases, to the
| appearance of life on Earth.
|
| The icy bodies from the outer Solar System that contain
| such organic substances are very easily vaporized during
| entry in the atmosphere of the Earth, so only a
| negligible fraction, if any, of the organic substances
| originally present in such a body would reach the surface
| of the Earth.
| soco wrote:
| So we get organic vapors in the atmosphere right.
| Shouldn't that matter?
| adrian_b wrote:
| One theory is that the primitive Earth contained much
| smaller quantities of the volatile chemical H, C, N, O
| and S, which are the main constituents of water and of
| organic substances.
|
| Then Earth collided with a great number of small bodies
| formed in the outer Solar System, which were rich in
| water and organic substances. This has modified the
| composition of the Earth towards the current composition.
| (Later Earth has lost a part of its hydrogen; because
| hydrogen is very light, it is lost continuously from the
| upper atmosphere, after water is dissociated by
| ultraviolet light; thus now the Earth has less water than
| around the appearance of life.)
|
| This theory is likely to be true, so meteorites probably
| have brought a good part of the chemical elements most
| needed by living beings.
|
| However, most of the pre-existing organic substances from
| meteorites must have decomposed and whatever has been
| preserved of them could not have had any significant role
| in the appearance of life here, because any living being
| would have needed a continuous supply with any molecules
| that it needed, otherwise it would have died immediately.
| Such a continuous supply could have been ensured only for
| molecules that were synthesized continuously in the local
| environment here, not for molecules arriving sporadically
| in meteorites and which would have been diluted
| afterwards over enormous areas, down to negligible
| concentrations.
| foxglacier wrote:
| Wouldn't a big enough asteroid have an inner part which
| survives entry? You seem to be saying that it's
| impossible for any meteorite that might have these
| chemicals to not be completely vaporized which seems
| doubtful. Have you got a source?
| lazide wrote:
| The earths poles?
| kmaitreys wrote:
| 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.
| Sharlin wrote:
| It would've been specifically asteroids from beyond the
| "frost line", where it's cold enough for volatile
| substances to coalesce and stay solid.
| jvanderbot wrote:
| "volatile substances" is doing a lot of work. This means
| water and organics. Literal cold-storage seeds of life.
| general_reveal wrote:
| Exactly. The attempt to try to explain creation through
| science is often more absurd than the simple truth.
| blacksmith_tb wrote:
| "The simple truth" being Genesis, for which there can be
| no evidence possible?
| xandrius wrote:
| One thing I do agree with you: answering that an
| invisible dude did everything we don't get is much
| simpler indeed. Calling that a truth though.
| vpribish wrote:
| pray tell, where do we learn this simple truth?
| GetTheFacts wrote:
| >pray tell, where do we learn this simple truth?
|
| Praying[0] is a good start! That, coupled with large
| amounts of suspension of disbelief[1] helps too.
|
| I suggest drinking (or whatever your preferred brain-
| fogger might be) heavily. That helps you ignore the
| details -- because the "devil is in the details" and we
| mustn't have that, right?
|
| [0] Also known as "begging an _imaginary_ sky daddy for
| help "
|
| [1] https://en.wikipedia.org/wiki/Suspension_of_disbelief
| jmyeet wrote:
| 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?
|
| [1]: https://en.wikipedia.org/wiki/Panspermia
| edgyquant wrote:
| Paints the picture of an early solar system that was a fairly
| connected system. Perhaps life didn't form anywhere but
| Porto-life formed everywhere and earth is the only place that
| hasn't died yet
| 8bitsrule wrote:
| The major flaw in Panspermia is that it _all had to start
| somewhere_ without Panspermia. If it did that there, why not
| here?
| kmaitreys wrote:
| It had to start somewhere which is favourable to preserve the
| necessary molecules. Early Earth was not such place.
| michaelsbradley wrote:
| One way to think about that is time required:
|
| If earth is about 4 billion years old, but it takes say 400
| trillion years for natural processes to produce this
| chemistry, then it happened out there not here.
|
| This was a key reason why Hoyle preferred a steady state
| model of the universe -- the part of the universe we inhabit
| needs to be very, very old for this stuff to work out,
| according to his thinking. A minority opinion, for sure, his
| rejection of the Big Bang model and timelines lost him a lot
| of respect among his peers. And his ideas could be wrong, I'm
| just pointing out that historically panspermia proponents
| have taken this position as to "why not here".
| marcosdumay wrote:
| We know 2 things that are apparently incoherent:
|
| 1 - Abiogenesis is incredibly rare. We don't know how much
| exactly, but it's a lot.
|
| 2 - Abiogenesis happened on Earth about as soon as it became
| possible. Where "as soon as" means within half a billion
| years, but it's still way quicker than its rarity implies.
|
| A lot of people think panspermia is what made those two
| happen. Life had about a full billion years to appear in
| meteors before they could appear here.
|
| There are some problems, e.g. that each meteor only stayed
| chemically active for less than that half-a-billion years
| Earth had. Or that all the meteors that fell on Earth had
| only a fraction of the material that was later available
| here. But IMO, the largest issue is that just doubling the
| time is absolutely unsatisfying.
| adrian_b wrote:
| Life cannot appear in any of the small bodies that become
| meteors, because there is no source of energy for it.
|
| Life can appear only on big planets or on big satellites,
| like the big satellites of Jupiter and Saturn, if they have
| a hot interior and volcanism.
|
| Volcanism brings at the surface substances that are in
| chemical equilibrium at the high temperatures of the
| interior, but which are no longer at chemical equilibrium
| at the low temperatures of the surface, providing chemical
| energy that can be used to synthesize macromolecules.
|
| Solar energy cannot be used for the appearance of life.
| Capturing light requires very complex structures that can
| be developed only after a very long evolution and which
| cannot form spontaneously in the absence of already
| existing living beings.
|
| The only theory of panspermia that is somewhat plausible is
| that life could have appeared on Mars, which had habitable
| conditions earlier than Earth. Then, some impacts on Mars
| have ejected fragments that have fallen as meteorites on
| Earth and some remote ancestors of bacteria have survived
| this interplanetary trip.
|
| There are many meteorites on Earth that have their origin
| in impacts from Mars, so at least this part is known as
| being possible.
| nomel wrote:
| > because there is no source of energy for it.
|
| Couldn't it have started in the accretion disk?
| kmaitreys wrote:
| 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.
| HarHarVeryFunny wrote:
| > Wouldn't a couple asteroids be the literal drop in the ocean
| in comparison?
|
| Actually most water on earth probably came from asteroids, so
| they are the entire ocean! They would also have brought a lot
| of frozen methane and ammonia, so most of the chemicals
| necessary for terrestial life.
|
| When the solar system was forming, the protoplanetary ring of
| cosmic dust would have consisted of heavy elements (some
| essential for life, such as phosphorus) closer to the sun and
| frozen lighter elements further away. The heavy elements would
| have combined into the early rocky earth, and as the other
| planets formed and orbits stabilized the icy asteroids from
| further out would have been flung around and impacted the
| planets.
| dan_hawkins wrote:
| My layman guess would be that shortly after formation Earth was
| just a ball of lava that destroyed every organic component so
| when the surface solidified it was sterile.
| adrian_b wrote:
| There are 2 distinct kinds of claims made about the role of
| meteorites fallen on Earth whose origin is in such bodies like
| the Ryugu asteroid.
|
| One claim, which is likely to be true, is that in the beginning
| the Earth had a lower content of volatile elements, e.g.
| hydrogen, nitrogen, carbon, oxygen and sulfur, than today. The
| reason is that Earth has condensed at a high temperature, being
| close to the Sun, and those elements would not have condensed.
|
| Later, the Earth has been bombarded by a great number of
| asteroids formed far from the Sun, which were much richer in H,
| C, N, O and S, and this bombardment has provided a major part
| of the chemical elements required for water and for organic
| substances.
|
| A second, different claim, which is almost certainly false, is
| that this bombardment of the Earth has provided not only the
| raw chemical elements, but also pre-synthesized organic
| substances, like amino-acids and nucleobases, which have taken
| part directly in the origin of life.
|
| This second claim does not make sense. The meteorites rich in
| water and organic substances are extremely easily vaporized
| during atmospheric entry or during the impact with the surface
| and their content of organic substances would decompose.
|
| Even if we suppose that some falling bodies were so big that
| parts of them survived until the surface, any organic
| substances thus brought on Earth could not help in any way the
| appearance of life.
|
| Any form of life would need a continuous supply of such
| substances, otherwise immediately after consuming the few
| molecules adjacent to it the life form would die without
| descendants.
|
| Life can appear only in a place where there is a continuous
| supply of energy and it can use only chemical substances that
| are continuously synthesized in abiotic conditions. It cannot
| appear based on sporadic events, like the fall of a meteorite,
| which would also destroy anything at its place of impact.
|
| Such places where energy is available continuously and there
| are also the substances from which complex organic substances
| can be synthesized through catalysis by various minerals,
| mostly metallic sulfides, exist both on Earth and in other
| places in the Solar System. These are the places where either
| volcanic gases are released or similar gases are produced by
| the reaction of water with volcanic rocks, in hydrothermal
| vents. As far as we know, those are the places where life must
| have appeared, because all the necessary ingredients exist. The
| only mysterious part is how it has happened that a correct
| combination of the mineral catalysts required to synthesize all
| the needed organic molecules happened to be located in close
| proximity and in the right sequence.
|
| Today, even if such places still exist on Earth, life could not
| appear again. First, the oxygen from air would destroy any
| substances thus formed, and even where oxygen is missing the
| ubiquitous bacteria would consume any organic substances that
| could form abiotically, preventing their accumulation and the
| formation of any kind of structure from them.
| pfdietz wrote:
| > This second claim does not make sense. The meteorites rich
| in water and organic substances are extremely easily
| vaporized during atmospheric entry or during the impact with
| the surface and their content of organic substances would
| decompose.
|
| Such meteorites fall to Earth even today. Their interiors are
| often ice cold.
| kjkjadksj wrote:
| The missing part has been conducted in other experiments. I
| don't have time to give you some papers, but nucleic acids can
| self assemble into long chains under the right condutions. No
| polymerase enzyme is needed.
| pfdietz wrote:
| The conditions, while not requiring enzymes, are still highly
| artificial.
| shevy-java wrote:
| Yep, you are 100% correct. In fact, it is much more likely they
| were originating on Earth itself than a random hobo asteroid.
|
| > The missing part is how do they form self-replicating
| mechanisms capable of evolution.
|
| Well, there are some missing parts, yes, but RNA can self-
| replicate already; at the least some RNA can. Ribosomes also
| contain RNA so its is a ribozyme.
| pfdietz wrote:
| RNA can replicate in highly artificial conditions that would
| seem to already require life to occur.
| Vrondi wrote:
| Comets is where many astronomers have long thought the ocean
| came from. Comets are literal drops in our ocean. LOTS of
| comets. The atmosphere and the Earth at large would have been
| very different, and being bombarded by many giant space
| snowballs (along with asteroids) would have contributed
| materials. The missing part is, um, missing. We still do not
| know. However, these samples contained building blocks, not
| actual self-replicating RNA. That might seem like nothing, but
| before this discovery, we thought they only contained one
| ingredient.
| bartread wrote:
| > I'm no expert but this sounds strange.
|
| A cynic might suggest the theory might exist because nobody
| could figure out how life got started on its own on earth.
|
| The thing is I've never found the asteroid theory particularly
| satisfying either because it simply inserts another abstraction
| layer, explaining the problem away rather than explaining it.
|
| That's not to say it's wrong but, in its current incarnation,
| it's just a bit meh.
|
| I suppose perhaps that's part and parcel of it being a very
| hard problem to solve.
| mulmen wrote:
| > Wouldn't a couple asteroids be the literal drop in the ocean
| in comparison?
|
| Yes but the oceans are of extraterrestrial origin as well.
|
| https://en.wikipedia.org/wiki/Origin_of_water_on_Earth
| fusslo wrote:
| 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
| ceejayoz wrote:
| They seem pretty confident. There's been some conflicting
| reporting on contamination of the Ryugu samples over time.
|
| https://phys.org/news/2024-11-ryugu-asteroid-sample-rapidly-...
|
| > 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.
|
| https://www.isas.jaxa.jp/en/topics/003899.html
|
| > 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.
| fusslo wrote:
| ty ty! I usually just give a quick chatgpt buy my work
| blocked every ai but copilot
| Refreeze5224 wrote:
| Please don't just post slop anyone else could have gotten
| from AI. It undermines the entire purpose of this site, and
| reduces the quality of discourse drastically.
| bookofjoe wrote:
| https://science.gsfc.nasa.gov/sed/content/uploadFiles/public...
| fusslo wrote:
| you're the reason why I love HN.
| bookofjoe wrote:
| Thank you. Very kind of you to take the time and trouble...
| _ink_ wrote:
| Are these building blocks not evaporated on impact?
| stouset wrote:
| Only the outer surface of asteroids gets hot. Atmospheric entry
| isn't long enough to thoroughly cook a rock.
| drob518 wrote:
| What about the immense energy that is released when it slams
| into the earth at supersonic speeds?
| Symmetry wrote:
| A asteroid has to be absolutely huge to make it all the way
| down to the surface without slowing down to terminal
| velocity. Your typical 1kg asteroid will have slowed to
| terminal velocity dozens of km above the surface. The
| smaller an object the lower the ratio of its mass to
| surface area and the more easily it slows down.
| johnsmalles wrote:
| 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.
| qsera wrote:
| Doesn't multi-world interpretation pretty much answer how life
| originated?
|
| I mean, even if the starting state require to bootstrap life have
| impossibly low chance to happen random, multi-world
| interpretation implies that there will be some worlds where it
| happened, and observation of life is only possible in such
| worlds..
| kmaitreys wrote:
| Multi-worlds is not really relevant here. You are just asking
| the question how the building blocks of life form in the
| Universe and how can they reach a planet like ours.
| shevy-java wrote:
| That's not really new. It seems as if some people try to project
| "there is life outside of planet Earth". Well, the thing is ...
| is this question important? You already have life here. Synthetic
| biology will also progress. So why is it important if life is
| anywhere else? I don't understand it.
|
| There is nothing magic in RNA or DNA. Granted, right now we can
| not easily explain how life gets "bootstrapped", but recently
| there was a paper of self-propagating RNA even of a kind of semi-
| random sequence; this RNA can just amplify itself. I am sure you
| can find many more similar examples eventually as well as
| biochemical reaction processes that can be "bootstrapped" - and I
| am also sure none of these work on an asteroid. So why is there
| this strange focus on "life outside of planet Earth"? Some people
| want research money, that is clear now.
| stevenjgarner wrote:
| Ummm ... the "Victoria University of Wellington in Australia"?
| Please. Victoria University is located in Wellington, New Zealand
| [1]. Nothing to do with Australia. Dr. Morgan Cable is a Senior
| Lecturer in Space Science at Te Herenga Waka, Victoria University
| of Wellington in New Zealand [2]. Can't believe that phys.org
| would publish such an error.
|
| [1] https://www.wgtn.ac.nz/
|
| [2] https://www.psi.edu/staff/profile/morgan-cable/
| Amorymeltzer wrote:
| I'm in the middle of reading Peter Brannen's _The Story of CO2 Is
| the Story of Everything_ --it's excellent and goes deep into the
| (bio)geochemistry of Earth--and he presents a good case for a
| metabolism-first development of life, taking advantage of "a
| disequilibrium that needed to be relieved at the vents, an
| unending stream d free energy to dissipate," rather than the RNA
| information-first theories.
|
| It fits his overall narrative but it was an interesting way to
| think about life "as a thermodynamically necessary mechanism to
| relieve the continuous production of free geochemical energy on
| Earth... more efficiently than abiotic processes could." (Brannen
| quoting complex-systems scientist Anne-Marie Grisogono) I highly
| recommend the book.
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