[HN Gopher] NASA's Asteroid Bennu Sample Reveals Mix of Life's I...
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NASA's Asteroid Bennu Sample Reveals Mix of Life's Ingredients
Author : zrkrlc
Score : 104 points
Date : 2025-01-31 13:19 UTC (3 days ago)
(HTM) web link (www.nasa.gov)
(TXT) w3m dump (www.nasa.gov)
| bruce511 wrote:
| While it's unlikely this really moves the needle in terms of
| other life in the solar system (which seems like a pretty hard
| "no" to me as a lay person), it perhaps does have an impact on
| "rest if the galaxy".
|
| Of course the ingredients are "necessary but not sufficient ".
| However being "abundant" increases the chance of them being
| present when the other necessary conditions are met.
| gyomu wrote:
| > other life in the solar system (which seems like a pretty
| hard "no" to me as a lay person),
|
| There's so much we don't know about the solar system, little
| bacteria crawling around deep under the crust of a moon or
| swirling about in a gassy giant doesn't seem too far fetched.
|
| Wormy fishy creatures (or even more complex than that) under
| the ice of Europa is a bit more of a stretch, but even then I
| don't think we're aware of anything that would outright refute
| that possibility as of now.
| ceejayoz wrote:
| Yeah, ruling anything out when we're still finding new
| muscles (https://thehill.com/changing-america/well-
| being/medical-adva...) and weird structures
| (https://www.science.org/content/blog-post/what-s-obelisk-
| any...) in humans - to which we have plenty of access - seems
| deeply premature.
| mrguyorama wrote:
| The traditional way to demonstrate this is how little we
| know about the ocean floor _and the types, styles, and
| varieties of life therein_.
|
| Every time we look we find a textbook's worth of new types
| of creatures, and usually break at least one minor "rule"
| of how life works, for example, "dark oxygen".
| lm28469 wrote:
| And people tend to forget about time. There might have been
| bacterias somewhere 1b years ago or in 1b years.
|
| Space is big as fuck but when you add time in the mix it's as
| close to infinite as you can get.
| someothherguyy wrote:
| At least wait for https://en.wikipedia.org/wiki/Europa_Clipper
| raverbashing wrote:
| Yeah
|
| I'm thinking this definitely pushes the start of life in the
| bigger universe some billion years before the start of life on
| Earth. Possibly a lot of billion years.
|
| (though you still need a couple of generations of stars to get
| carbon, nitrogen and phosphorus)
| baq wrote:
| Let's wait for the Europa lander and nuclear submarine to make
| sure. Chances are slim but not zero.
| itishappy wrote:
| We have no plans for anything like that. Few proposals, but
| nothing concrete. Europa Clipper is what we've got for now.
| baq wrote:
| > We have no plans for anything like that.
|
| That's kinda my point... I'm pretty sure I won't live long
| enough to see it happen, but I hope we plan and launch a
| mission like that!
| Symmetry wrote:
| Life arose on Earth shockingly quickly on Earth as best as we
| can tell from the fossil record. Especially compared to
| apparently much more difficult innovations like photosynthesis,
| mitochondria, or multi-cellularity. I wouldn't at all be
| surprised if bodies in the solar system with liquid water and
| active enough geologies to produce consumable chemicals have
| primitive life.
| mapt wrote:
| One of the inputs to this that has shifted recently is that
| scientists are finding it difficult to locate a core sample
| of solid rock, anywhere, that is completely sterile. It seems
| like ecology percolates through almost anything in the crust
| with pore spaces and a temperature under or at 100C or so.
|
| That shift from "Opportunities for life" being measured based
| on surface area to volume is dramatic.
| hirokio123 wrote:
| The theory of physicochemist Arrhenius strongly suggests that we
| are the descendants of life that arrived on Earth carried by
| spores from space.
| adrian_b wrote:
| By the time when Arrhenius proposed this theory he did not
| really have any argument supporting it.
|
| Now, there exists only one argument supporting it.
|
| The last common ancestor of all cellular living beings that
| exist on Earth was already a quite complex bacterium.
|
| There is no doubt that it was the product of an already very
| long evolution process. For instance the genetic code that is
| used, with very small variations, by all living beings on Earth
| must have succeeded a long sequence of simpler genetic codes,
| with an increase of each step of the complexity of the code and
| of the number of amino-acids that could be encoded.
|
| The oldest versions of the genetic code are likely to have
| encoded only between 4 and 6 amino-acids instead of 20 to 22,
| like today.
|
| Based on the probable bacterial fossils that are quite old, it
| seems like the time from the apparition of life on Earth might
| have been too short to explain the complexity of the last
| common ancestor of the present living beings.
|
| So this supports the idea that life could have appeared
| elsewhere, but then some bacteria and viruses have reached
| Earth and then they have evolved further.
|
| Even in the unlikely case when this supposition were true, this
| changes nothing about the appearance of life, it just pushes it
| to another place that must have had a pretty much identical
| environment with the primitive Earth, in order to make possible
| the apparition of life.
|
| Life cannot appear without a continuous source of energy for
| it. There exists only one known source of energy that can be
| used by the simplest possible forms of life, and this source of
| energy is the internal heat of a relatively big planet or of a
| very large satellite, like Titan or the big satellites of
| Jupiter.
|
| The internal planetary heat can provide the energy for
| sustaining life indirectly, through volcans or hydrothermal
| vents. When volcanic rocks are ejected from the hotter inside
| of a planet, they consist of chemical substances that are no
| longer in chemical equilibrium at the lower temperature of the
| planet surface. This causes chemical reactions that result in
| substances like free dihydrogen, which, in the presence of
| catalysts, make possible the continuous synthesis of the
| complex organic molecules required for life.
|
| As far as we know, Earth had ideal conditions for the
| appearance of life right here. It did not need to be colonized
| by bacterial spores coming for elsewhere.
|
| The only reason why there is a very small chance for Arrhenius
| to have been right, is that the bigger Earth has remained very
| hot for a longer time than smaller planets like Mars, delaying
| the apparition of life here.
|
| So it might have been possible for a place like Mars to have
| conditions suitable for the appearance of life before Earth.
| Life could have been appeared there and it could have been
| transported by one of the many meteorites that are known to
| have come from Mars to Earth as a consequence of big impacts.
|
| Then Mars has lost most of its atmosphere and it became very
| cold, so if it ever had life, that could have disappeared.
|
| For now this scenario that would match the theory of Arrhenius
| cannot be considered as 100% excluded, but in any case it is
| far-fetched and it does not change anything about the evolution
| of the living beings known on Earth, even if the initial part
| of that evolution could have taken place elsewhere, but in
| conditions not really different from those of the primitive
| Earth.
| exe34 wrote:
| my favourite hypothesis for the first life is the idea that
| the entire universe might have been habitable for a while:
| https://arxiv.org/abs/1312.0613
|
| of course, it's very unlikely, but it's such a cool idea!
| adrian_b wrote:
| It is indeed a cool idea, but it is likely completely
| wrong.
|
| For life, it is not enough for the ambient temperature at
| the surface of a planet to be acceptable.
|
| For life to appear, it is necessary that the interior of
| the planet is much hotter than the surface, so that this
| thermal non-equilibrium will be converted into chemical
| non-equilibrium by volcanism.
|
| When the universe had cooled to a habitable temperature
| after the Big Bang, if any celestial bodies existed they
| were in thermal equilibrium, so they could not provide any
| energy for the appearance of life.
|
| The internal heat of a planet normally has 2 sources, the
| radioactive decay of heavy elements that have been produced
| only in catastrophic events that have happened late in the
| history of Universe, e.g. supernova explosions or neutron
| star impacts, and the residual heat produced from
| collisions with other planets.
|
| For satellites close to big planets or for planets close to
| stars there may be also heat produced by tidal
| deformations.
|
| Such sources of heat are unlikely to have existed in the
| early Universe, and even supposing that collisions could
| have existed, in that case the environment with a life-
| enabling temperature would not have been correlated with
| the epoch when the entire Universe had a temperature that
| now is suitable for life.
|
| Moreover life cannot appear without chemical elements up to
| the iron-cobalt-nickel group, which are the chemical
| catalysts on which life depends as much as on the
| structural elements HCNOS.
|
| The iron group elements are generated only late in the
| lifetime of a star, so life can appear only in celestial
| bodies that recycle matter from explosions of the first
| generation stars, billions of years after the Big Bang and
| long after the Universe had cooled.
| netcraft wrote:
| Given that the Ryugu sample was contaminated, how confident are
| we that these samples werent also contaminated?
|
| https://phys.org/news/2024-11-ryugu-asteroid-sample-rapidly-...
| ceejayoz wrote:
| https://www.rochester.edu/newscenter/nasa-bennu-asteroid-spa...
|
| > Key to the curation process was the use of so-called "witness
| plates"--flat plates made of aluminum and sapphire--that were
| exposed to all the same conditions as the sample from Bennu,
| creating a detailed record of potential contaminants.
|
| > If a compound found in the Bennu sample wasn't on the witness
| plate, scientists could confidently identify it as originating
| from Bennu. This is critical when dealing with organic
| compounds, where contamination can make it hard to distinguish
| what is truly extraterrestrial.
| gus_massa wrote:
| > _Many amino acids can be created in two mirror-image
| versions, like a pair of left and right hands. Life on Earth
| almost exclusively produces the left-handed variety, but the
| Bennu samples contain an equal mixture of both._
|
| This is a very strong indication that the amino acids in the
| sample where made by an inorganic process.
| AnimalMuppet wrote:
| Is it? Or is it a very strong indication that the amino acids
| in the sample were _not contamination by life on Earth_?
|
| That is, while life on Earth is left-handed, I don't know of
| any reason to assume that life elsewhere must be either left-
| or right-handed.
|
| I don't actually believe in panspermia. I just think that
| it's important to not infer more than the evidence actually
| gives.
| Out_of_Characte wrote:
| Life uses the exact same chemistry as any inorganic process
| exept life is far more competent than random reaction
| products. This is why the expected origin is inorganic as
| left handed and right handed are equally likely to occur in
| an inorganic process. So occams razor suggests that either
| 1) life must specifically balance their left-right handed
| molecules 2) Other processes that favor any handedness must
| not be present.
|
| or the process is inorganic which we know couldn't favor
| left or righthandedness in the first place.
| gus_massa wrote:
| I agree. My version:
|
| I would not be surprised if we find life in other
| planet/moon that use "only" [1] right handed amino acids.
| But it looks like it's easier to produce "only" one type
| of them: "only" left handed or "only" right handed.
|
| To produce both in a 50%-50% ratio they would need to
| duplicate most of the enzymes, or have a specialized
| enzyme that transform one into the other. It's not
| impossible, but it seams to be wasteful.
|
| Nobody is sure, but our current best guess is that life
| in other planets/moons will choose left or right instead
| of a 50%-50% mix.
|
| [1] Life on Earth use a small amount of right handed
| amino acids, so I expect a "mirror" life to use a small
| amount of left handed amino acids.
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