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Saturn's largest moon most likely uninhabitable

132 points by wglb 3y ago

renewiltord 3y ago
I see. The reason for this is that insufficient surface organic materials make it into the liquid water and the only kind of life we know requires those two to combine. Unlucky, I suppose. Would have been pretty cool!
- generic92034 3y ago
  Questions popping up in my mind: 1) Why are organic materials (probably any carbohydrates) only supposed to come from the surface? Would it not be plausible to assume that Titan's ocean ground contains significant amounts of carbon? 2) Why do they assume that there are only dilution processes in an ocean (surface or subsurface). There could be currents and suboceanic terrain features concentrating carbon-rich water (at least I do not know any reason against this).
  - RIMR 3y ago
    These are great points. It would be like if a race of flying / buoyant aliens studied Earth's upper atmosphere, and decided that it wasn't sufficient for life, while ignoring that life isn't really found until you get to the surface, and most of that life is found under the surface. There could be a habitable zone deep in Titan's oceans. I don't even know if "habitable" is the right word, because the concern seems greater to do with the genesis of life, not the sustainability of existing life that might have existed on Titan for millions of years already, from a time where perhaps conditions were very different from what they are today.
    - margalabargala 3y ago
      To be fair, the scientists that wrote the scientific article came to no such conclusion. The "most likely uninhabitable" thing is an invention of the popsci journalist whose article was linked, not something supported by the underlying journal article. The journal article asked the question "is the carbon transferred from Titan's surface to its ocean sufficient, on its own, to sustain a biosphere?" to which their answer is "probably not". It explicitly does not claim there are no other sources of carbon in the ocean, nor that Titan is "probably uninhabitable".
  - margalabargala 3y ago
    The actual study this article is about is addressing a very specific question. The article posted takes that specific conclusion and applies it more generally, especially when writing the headline. Titan has a methane atmosphere, due to prior outgassing from its surface. Methane is destroyed by sunlight; i.e. over time, the atmosphere is reacting with itself and sunlight to form more complex carbon molecules, which fall out of the atmosphere onto the surface. The study does not look at the carbon content of the ocean itself, it simply evaluates whether these complex carbon molecules, that we know are forming in Titan's atmosphere through well-understood processes, can also mix with the liquid ocean. As the ice sheet covering the ocean is at minimum 40km thick, and over 100km thick in places, it is difficult for surface molecules to penetrate. Whether or not other carbon sources, such as from within the planet, contribute carbon to Titan's oceans are beyond the scope of this study, and will remain beyond the scope of our knowledge until we manage to place equipment on Titan capable of drilling through tens of kilometers of ice. The actual paper concludes that carbon transfer from the surface to the ocean is not sufficient to support a biosphere if that is the sole source of carbon. It specifically calls out "unless biologically available compounds can be sourced from Titan’s interior" as something that would allow a biosphere. EDIT: link to article full text: https://www.researchgate.net/publication/377929149_Organic_Input_to_Titan%27s_Subsurface_Ocean_Through_Impact_Cratering https://www.researchgate.net/publication/377929149_Organic_I...
    - generic92034 3y ago
      Ah, I see. My bad for not drilling deeper and reading the underlying study. In my eyes neglecting the inner planet as source of carbon (only referring to the article here) is a rather large gap. I am all for shooting some equipment up to Titan. Although I am not sure we have the technology and the will to commit resources to analyze Titan's oceans in detail, yet.
      - margalabargala 3y ago
        No worries. I think it's reasonable to expect that people who write articles about journal articles would do a good job describing their conclusions. The whole point is that reading the underlying study shouldn't be necessary. I think this was an important study to be done, because if the conclusion came out the other way, that would have been very exciting. We would then be able to say "using only the aspects of Titan we know for certain to be true, we can model a plausible sustainable biosphere". A positive result would have been very promising, but this negative result should not be seen as discouraging.
  - thaumasiotes 3y ago
    > Why do they assume that there are only dilution processes in an ocean (surface or subsurface). Presumably for the same reason that mine operators assume that all minerals are evenly distributed throughout the earth's crust.
pavlov 3y ago
> ‘"One elephant per year of glycine into an ocean 12 times the volume of Earth's oceans is not sufficient to sustain life," said Neish. "In the past, people often assumed that water equals life, but they neglected the fact that life needs other elements, in particular carbon."’ Titan’s underground ocean is 12x larger than the Earth’s oceans? I had no idea. Wow. If this result holds, it’s a shame because the gas giant moons always seemed like the only chance of discovering some interesting extraterrestrial life within my lifetime (or the next few dozen generations — the stars are incomprehensibly distant and nearly impossible to visit).
- NoMoreNicksLeft 3y ago
  Can't we send two elephants per year? Do they even have to be elephants, or can we send plain glycine?
  - sph 3y ago
    How many elephants per olympic-sized swimming pool? Per (american) football field? I have never seen any of those things in real life, yet journalists making stupid comparisons. I guess the field must be full of people that were deathly afraid of maths and numbers.
    - ryukoposting 3y ago
      Wait, wouldn't a football field be a unit of area? How many elephants per cubic football field?
      - qsi 3y ago
        A football field is an area, so a cubic football field would be a six-dimensional volume.
        eru 3y ago
        They are talking about a (cubic football) field. Cubic football is played in three dimensional 'fields', not on flat patches of grass.
travisporter 3y ago
Props to Neish - negative results would jeopardize the nasa dragonfly mission (co-PI) but still got it published
- johngossman 3y ago
  Reading closer, they point out, "It is nearly impossible to determine the composition of Titan's organic-rich surface by viewing it with a telescope through its organic-rich atmosphere," said Neish. "We need to land there and sample the surface to determine its composition."
RIMR 3y ago
I don't disagree with the assumptions made here, but the conclusion is bad. Titan is likely unihabitable for life as we know it. There are plenty of extremophiles here on Earth that live in places we wouldn't expect life to exist, but we know that they can because we found them. If we make conclusions that we cannot find life on Titan, then we never will because we won't be looking. Life could be thriving on Titan, but we won't know unless we look for ourselves. Also, for all we know, Titan's oceans are loaded with organic compounds that are don't originate from the surface. We don't know what the actual internal structure of Titan looks like because we lack the data.
- mbauman 3y ago
  Yeah, that's not at all what the actual journal article claimed. It starts super simple: We know Titan has two things that seem so promising for life as we know it! Organic compounds on the outside, liquid water on the inside. And then it asks: Might those two promising things meet? Other work hasn't found the tectonics that would do it; could cratering do it? And that very particular answer is pretty definitively no.
- thriftwy 3y ago
  Titan is likely habitable for life as we know it. It's hard to imagine why Titan won't have life around hydrothermal vents and the like.
andrewstuart 3y ago
Is there anyone on Earth who thinks it might have been habitable, at -292 degrees Fahrenheit (-180 degrees Celsius). Its weird that there's any narrative at all around this.
- StanislavPetrov 3y ago
  There is a massive ocean of liquid water, which indicates that it is substantially warmer than that.
- dang 3y ago
  "Please don't post shallow dismissals, especially of other people's work. A good critical comment teaches us something." https://news.ycombinator.com/newsguidelines.html https://news.ycombinator.com/newsguidelines.html
- margalabargala 3y ago
  There's a theory that life on Earth began at extremely cold temperatures, yes; below -100F. https://www.discovermagazine.com/planet-earth/did-life-evolve-in-ice https://www.discovermagazine.com/planet-earth/did-life-evolv... It's only Titan's surface that is at -292F, anyway, The theory is that life, if it exists, would be present in the subsurface ocean, which would be significantly warmer.
  - mr_toad 3y ago
    Actually there is speculation that methane or ethane based life could exist on the surface.
    - margalabargala 3y ago
      Sure, there is "speculation" about pretty much anything and everything. There's speculation that quantum flux based life could exist on the surface of the sun. The speculation that is based on things we already know to be possible, speculates that life could be possible in the subsurface ocean.
dougmwne 3y ago
This doesn’t seem to be a very meaningful theory to draw conclusions about life. We have no idea how much carbon is already present in Titan’s ocean and if there’s need for a water cycle that connects to the surface. Also this study only considers impact craters, not surface tectonics. And there could be plenty of carbon sources from ocean floor interactions.
- margalabargala 3y ago
  The journal authors agree with you. The "most likely uninhabitable" conclusion is an invention of the popsci article's author. The actual article's conclusion is basically "for there to be life on Titan, there needs to be more carbon in the ocean than would be transferred solely by surface impactors". It absolutely does not rule out the existence of those carbon source.
  - thereddaikon 3y ago
    As usual, the reporting on science ends up distorting or even inventing conclusions out of thin air.
    - margalabargala 3y ago
      To quote the two concluding sentences of the journal article: > It is unlikely that the calculated ﬂuxes are sufﬁcient to maintain a detectable biosphere, unless the thickness of organics on Titan’s surface is greater than currently estimated, abundant biomolecules are available from Titan’s rocky core, or surface biomolecules can be delivered to the ocean by a process other than impact. Our calculations suggest that despite Titan being the most organic-rich ocean world in the Solar System, this does not automatically imply an organic-rich and habitable ocean.
    - shiroiushi 3y ago
      I feel like science reporting would actually be greatly improved if they simply had ChatGPT write the articles. The human "reporters" they have now are terrible.
JoeAltmaier 3y ago
Perhaps a historical impact could have been large enough to seed the ocean.
andrewflnr 3y ago
The abstract of the actual paper only claims: > Unless biologically available compounds can be sourced from Titan's interior, or be delivered from the surface by other mechanisms, our calculations suggest that even the most organic-rich ocean world in the Solar System may not be able to support a large biosphere. Which is much less sensationalist, to put it politely.
- arp242 3y ago
  Which is just a different way of saying "uninhabitable". The middle of the Sahara is uninhabitable. Unless you introduce sufficient water and plants that is.
  - andrewflnr 3y ago
    It is not "just a different way". There's no reason to assume impact melting from the surface is the only source of carbon in Titan's ocean. The authors of the study seem clear on this. I don't know why you feel the need to stand up for phys.org on this, or why you think the Sahara is relevant.
  - lucb1e 3y ago
    Except, if I understand them correctly: they don't know what the Sahara's core is made of and might supply for life, to keep the analogy Not that that makes it likely to be hospitable. I'm only surprised by the headline because I wouldn't have thought anyone had expected anything different, so a headline like "as uninhabitable as you might figure" would have made more sense, but nevertheless this doesn't rule it out to about the same extent as it wasn't deemed unlikely already in my perception (as a follower of space news)
  - BirAdam 3y ago
    Well… the Sahara has life though. It isn’t abundant, but it’s certainly there.
    - andrewflnr 3y ago
      Indeed, there's quite a gulf between not having "a large biosphere" and having no biosphere at all.
pvaldes 3y ago
> One elephant per year of glycine into an ocean 12 times the volume of Earth's oceans is not sufficient to sustain life". This reasoning is too limited IMAO. Titan oceans may not have whales, but for sure could still afford a lot of animals. 1) It seems that Titan has been there since the early phases of solar system creation, so I'll assume that is older than 3 billions of years (to pick a conservative value). One elephant a year for 3 billions of years is still a lot. 2) Titan could have been bombed with much more matter on the early phases of solar system history. 3) Live on earth is perfectly able to cope with a poor nutrient aquatic environment. Most of the earth falls exactly on this category after all. 4) Some life forms need just a little bit of carbon to be functional. Earth has very big animals that are 99% water. 5) Cold water promotes slow metabolism. Life just adapts growing really slow, being carried by currents, and adopting a poiquiloterm life style.
- deleted 3y ago
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- nearbuy 3y ago
  Though it's not clear from the article, I think they aren't concerned about the physical material. This organic matter could be an energy source for life and they're saying that it's not enough energy. Even if a lot of stored energy had accumulated, it's not sustainable, and life exhibits exponential growth when food is plentiful.
  - pvaldes 3y ago
    If the water on Titan is liquid [1], by definition some source of energy is warming it over zero Celsius degrees. And if there are huge oceans of liquid water, the source of energy somewhere must be huge also. This is all that life needs to thrive. Entire ecosystems on Earth developed at high pressures, close to catastrophic scorching temperatures, without the need of any sunlight or photosynthesis, just using chemical energy from hydrothermal vents. This does not prove that Titan has life, but life has proven several times that can flourish in such circumstances. I'm not an astrobiologist and can miss essential details about the moon, but in my opinion being isolated under a several km layer of ice, with cold and absolute obscurity, does not prevent life on Titan at all, because it didn't prevented it on Earth. Bioluminiscence still ranks among the more common methods of communication on Earth. [1] (Having salt on the water could help a lot with that liquid state. I assume that we could find easily several layers of saltwater and also methane) But after some good replies above, it seems that the real question here is not "if the water is liquid" as much as "if the liquid is water". That changes the game totally.
vel0city 3y ago
This is talking about estimated average comet/asteroid impacts, right? If we're going by the average asteroid impacts on even million-year timescales causing radical changes to a heavenly body, we'd end up with no moon. I definitely get this is a limited research here, and I'm not faulting it for that. Its good to know it seems like this kind of cycle wouldn't be consistent in adding organic molecules to the subsurface oceans. But let's not necessarily see this as "there's no way organic molecules could have been pushed down in relevant amounts."
deadbabe 3y ago
Uninhabitable as in we couldn’t introduce basic life forms there even if we tried?
- animal531 3y ago
  I'm sure we could introduce some extremophiles. Here on Earth we have organisms living anywhere, including inside of rocks!
gweinberg 3y ago
The article seems to treat speculation with more confidence than it deserves, and also to report estimates with unjustified level of precision. For example, it claims the annual amount of glycine transferred to Titan is equal to the mass of "a male African elephant" rather than simply an elephant.
- fnordpiglet 3y ago
  I always find the metaphorical estimates in science reporting absurd. I don’t know why the mass of a male African elephant is in any way more visceral than 6000 kg (btw a quick google search gives a band of 1800 to 6300kg, which isn’t particularly precise). Given Titan is about 4.5 billion years old this could be an enormous amount of complex carbon transferred from the surface assuming it’s more or less a one way process.
ramesh31 3y ago
There's always Europa
- skirmish 3y ago
  “ALL THESE WORLDS ARE YOURS – EXCEPT EUROPA. ATTEMPT NO LANDING THERE.”
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aaroninsf 3y ago
Saw this lack week and frankly I don't know why it's getting attention. Alright, I suppose I do actually. Its right up there with Fermi paradox papers wrt the number of wide and wild assumptions required to justify a dramatic headline and clickbait-ha-ha measurement like "one elephant." It's a reasonable hypothesis, but despite the drama, this sort of thing has no predictive power in our actual universe. Only one where those assumptions all hold. Could be ours. Probably not though.
slater 3y ago
Europa it is, then! Were there any warnings about landing there?
- robertlagrant 3y ago
  I know it's not what you're referring to, but I just watched something even more on the nose![0] [0] https://www.imdb.com/title/tt2051879 https://www.imdb.com/title/tt2051879
perihelions 3y ago
- "These fluxes suggest an upper limit for biomass productivity of ∼10³ kgC/year from a glycine fermentation metabolism." This is really an upper bound on accessible energy (the "carbon" explanation in the press office release is hand-wavey). The idea is that solar photochemistry in Titan's atmosphere creates chemical energy gradients, in the form of energetic compounds like that glycine; and these energy gradients could migrate through the ice and support a biosphere in the subsurface ocean. The abstract* says that, actually, very little of that energy gradient can get through the ice shell. This situation is different from that of some of the other icy moons: they potentially have much larger geochemical energy sources, from chemical reactions between the water ocean and primordial rock. The problem with Titan is it (probably) has a weird ice shelf on the bottom of its underground ocean, which isolates it from rock. So rock-ocean weathering probably doesn't happen there. * (The paper's not on arXiv or SciHub if you were wondering)
- kurthr 3y ago
  Of course one could say the same about oil, coal, and gas on the earth. We're burning a 100 million years of bio productivity. Any such bio productivity could have been occurring and being stored on Titan for 10^8 years as well. It might not be sustainable. I don't know.
BirAdam 3y ago
No matter the estimation, no matter the probability, the history of scientific inquiry has shown that reality is weirder than the wildest of human imaginings. Let’s just go and find out for sure, and maybe write less clickbait, yeah?
alberth 3y ago
TIL: that some moons have atmospheres. https://futurism.com/the-atmospheres-on-our-moons https://futurism.com/the-atmospheres-on-our-moons
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Freedomboy 3y ago
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matt3210 3y ago
Replace “life” with “life as we know it”
DoreenMichele 3y ago
Life as we know it here on Earth... Water, carbon, etc. I heard eons ago that Spock's green blood was inspired by the blue-green blood of horseshoe crabs which has a copper-based system instead of iron, among other oddities: A horseshoe crab's blood has a blue to blue-green color when exposed to the air. The blood is blue because it contains a copper-based respiratory pigment called hemocyanin. https://dnr.maryland.gov/ccs/Pages/horseshoecrab-medical.aspx https://dnr.maryland.gov/ccs/Pages/horseshoecrab-medical.asp... Though this piece contradicts that origin story: https://www.mentalfloss.com/article/578911/why-star-treks-mr-spock-has-green-blood https://www.mentalfloss.com/article/578911/why-star-treks-mr... I'm failing to come up with the right search terms to find what I recall about zooplankton and the oceanic food web. It differs from other food webs and this shows up starkly in certain kinds of charts/models. Zooplankton are tiny creatures found in relatively small amounts on the surface but breed like crazy and feed huge animals, including some types of whales. So where other food webs are kind of pyramidal and you have a huge amount of plants at the base of the web and a smaller amount of animals that eat those plants and a smaller mass of animals that eat those animals, the ocean's food web doesn't follow a similar pattern. It's not pyramidal. There is much more mass found in other layers of the food web than of zooplankton at any given time. (Included because of the claim that "One elephant per year of this substance can't sustain life..." How do we know that?) Furthermore, on Earth we have life sustained by undersea volcanoes which defies our usual patterns of life. I'm out of my depth on exactly how these lifeforms differ from the norm on Earth, so I won't try to give a nutshell version of how they differ, but here are some links: https://oceantoday.noaa.gov/underwatervolcanoes/ https://oceantoday.noaa.gov/underwatervolcanoes/ https://www.mpg.de/19982028/0309-mbio-life-in-the-smoke-of-underwater-volcanoes-154772-x https://www.mpg.de/19982028/0309-mbio-life-in-the-smoke-of-u... https://en.wikipedia.org/wiki/Sulfurimonas https://en.wikipedia.org/wiki/Sulfurimonas That's what I know as a former homeschooling mom and Earthbound human who reads. Surely we can do a little better than "It doesn't readily match the patterns of the dominant lifeforms of this planet, so we cannot imagine that some other planet with dramatically different chemical makeup and other details has lifeforms that are fundamentally different from that, and never mind that Earth has some oddities living on it." Cue the plot from the Star Trek episode where humans were being attacked by the guardian of the eggs that they were destroying willy-nilly without realizing they were eggs: https://en.wikipedia.org/wiki/The_Devil_in_the_Dark https://en.wikipedia.org/wiki/The_Devil_in_the_Dark
ssijak 3y ago
There are so many variables that I am not sure that they can conclude anything substantial like they are trying based on this calculation alone. Titan is old 4 billion years. That alone is enough to not be able to conclude that its oceans are poor in organics. So many things could have happened during the evolution of Titan during those 4 billion years that we just don't know about. Plus what about mixing from under the oceans. I vote for sending meaningful probes as soon as we have tech for it. I dream of an era where humanity will spend 1 trillion per year on exploratory space tech and not on war machinery.
- shiroiushi 3y ago
  >I vote for sending meaningful probes as soon as we have tech for it. I dream of an era where humanity will spend 1 trillion per year on exploratory space tech and not on war machinery. What if your peaceful probe starts an interplanetary war with the inhabitants of those oceans?
omneity 3y ago
I found the language in this article to be very strong and it seems to me this discovery only rules out a specific glycine exchange mechanism to power life reactions. The paper contrastingly is rather descriptive and much less assertive, and doesn’t jump to the same conclusions the article is pushing. You would expect this from a tabloid headline rather than Phys.org.
southernplaces7 3y ago
While we have no idea what kinds of landscapes and terribly esoteric environments life in some form could endure (since our only basis for comparison is the flora and fauna of our own evolutionary tree), I always though it was absurd to assume life on Titan just because it has water. The conditions out by the orbit of Saturn are hellish, even for a body of water protected by a vast surface shield of hard material.
- hoseja 3y ago
  Says the guy made of hydric acid, currently submerged in vast pool of molecular oxygen.
  - southernplaces7 3y ago
    touche! But more seriously, an interesting project would be to simulate the conditions of our solar system's "candidate" for life ecosystems in laboratory conditions as precisely as we can based on known information, and then subject some of the toughest microorganisms we have living on earth to them, to see if at least they could survive or even thrive. For example: recreate conditions of pressure, cold, radiation and chemical composition like those we think are the case in Titan's subterranean ocean, and then see how well a colony of water bears (tardigrades) endures. Seems a lot more practical then speculating. I'm curious if this has been done in a systematic way by any organization on Earth.
hoseja 3y ago
JFC, water-carbon chauvinism again.
matthewfelgate 3y ago
The NASA Dragonfly project to Titan looks very interesting.

132 points by wglb 3y ago

I see. The reason for this is that insufficient surface organic materials make it into the liquid water and the only kind of life we know requires those two to combine. Unlucky, I suppose. Would have been pretty cool!

generic92034 3y ago
Questions popping up in my mind: 1) Why are organic materials (probably any carbohydrates) only supposed to come from the surface? Would it not be plausible to assume that Titan's ocean ground contains significant amounts of carbon? 2) Why do they assume that there are only dilution processes in an ocean (surface or subsurface). There could be currents and suboceanic terrain features concentrating carbon-rich water (at least I do not know any reason against this).
- RIMR 3y ago
  These are great points. It would be like if a race of flying / buoyant aliens studied Earth's upper atmosphere, and decided that it wasn't sufficient for life, while ignoring that life isn't really found until you get to the surface, and most of that life is found under the surface. There could be a habitable zone deep in Titan's oceans. I don't even know if "habitable" is the right word, because the concern seems greater to do with the genesis of life, not the sustainability of existing life that might have existed on Titan for millions of years already, from a time where perhaps conditions were very different from what they are today.
  - margalabargala 3y ago
    To be fair, the scientists that wrote the scientific article came to no such conclusion. The "most likely uninhabitable" thing is an invention of the popsci journalist whose article was linked, not something supported by the underlying journal article. The journal article asked the question "is the carbon transferred from Titan's surface to its ocean sufficient, on its own, to sustain a biosphere?" to which their answer is "probably not". It explicitly does not claim there are no other sources of carbon in the ocean, nor that Titan is "probably uninhabitable".
- margalabargala 3y ago
  The actual study this article is about is addressing a very specific question. The article posted takes that specific conclusion and applies it more generally, especially when writing the headline. Titan has a methane atmosphere, due to prior outgassing from its surface. Methane is destroyed by sunlight; i.e. over time, the atmosphere is reacting with itself and sunlight to form more complex carbon molecules, which fall out of the atmosphere onto the surface. The study does not look at the carbon content of the ocean itself, it simply evaluates whether these complex carbon molecules, that we know are forming in Titan's atmosphere through well-understood processes, can also mix with the liquid ocean. As the ice sheet covering the ocean is at minimum 40km thick, and over 100km thick in places, it is difficult for surface molecules to penetrate. Whether or not other carbon sources, such as from within the planet, contribute carbon to Titan's oceans are beyond the scope of this study, and will remain beyond the scope of our knowledge until we manage to place equipment on Titan capable of drilling through tens of kilometers of ice. The actual paper concludes that carbon transfer from the surface to the ocean is not sufficient to support a biosphere if that is the sole source of carbon. It specifically calls out "unless biologically available compounds can be sourced from Titan’s interior" as something that would allow a biosphere. EDIT: link to article full text: https://www.researchgate.net/publication/377929149_Organic_Input_to_Titan%27s_Subsurface_Ocean_Through_Impact_Cratering https://www.researchgate.net/publication/377929149_Organic_I...
  - generic92034 3y ago
    Ah, I see. My bad for not drilling deeper and reading the underlying study. In my eyes neglecting the inner planet as source of carbon (only referring to the article here) is a rather large gap. I am all for shooting some equipment up to Titan. Although I am not sure we have the technology and the will to commit resources to analyze Titan's oceans in detail, yet.
    - margalabargala 3y ago
      No worries. I think it's reasonable to expect that people who write articles about journal articles would do a good job describing their conclusions. The whole point is that reading the underlying study shouldn't be necessary. I think this was an important study to be done, because if the conclusion came out the other way, that would have been very exciting. We would then be able to say "using only the aspects of Titan we know for certain to be true, we can model a plausible sustainable biosphere". A positive result would have been very promising, but this negative result should not be seen as discouraging.
- thaumasiotes 3y ago
  > Why do they assume that there are only dilution processes in an ocean (surface or subsurface). Presumably for the same reason that mine operators assume that all minerals are evenly distributed throughout the earth's crust.

pavlov 3y ago

> ‘"One elephant per year of glycine into an ocean 12 times the volume of Earth's oceans is not sufficient to sustain life," said Neish. "In the past, people often assumed that water equals life, but they neglected the fact that life needs other elements, in particular carbon."’ Titan’s underground ocean is 12x larger than the Earth’s oceans? I had no idea. Wow. If this result holds, it’s a shame because the gas giant moons always seemed like the only chance of discovering some interesting extraterrestrial life within my lifetime (or the next few dozen generations — the stars are incomprehensibly distant and nearly impossible to visit).

NoMoreNicksLeft 3y ago
Can't we send two elephants per year? Do they even have to be elephants, or can we send plain glycine?
- sph 3y ago
  How many elephants per olympic-sized swimming pool? Per (american) football field? I have never seen any of those things in real life, yet journalists making stupid comparisons. I guess the field must be full of people that were deathly afraid of maths and numbers.
  - ryukoposting 3y ago
    Wait, wouldn't a football field be a unit of area? How many elephants per cubic football field?
    - qsi 3y ago
      A football field is an area, so a cubic football field would be a six-dimensional volume.
      - eru 3y ago
        They are talking about a (cubic football) field. Cubic football is played in three dimensional 'fields', not on flat patches of grass.

travisporter 3y ago

Props to Neish - negative results would jeopardize the nasa dragonfly mission (co-PI) but still got it published

johngossman 3y ago
Reading closer, they point out, "It is nearly impossible to determine the composition of Titan's organic-rich surface by viewing it with a telescope through its organic-rich atmosphere," said Neish. "We need to land there and sample the surface to determine its composition."

RIMR 3y ago

I don't disagree with the assumptions made here, but the conclusion is bad. Titan is likely unihabitable for life as we know it. There are plenty of extremophiles here on Earth that live in places we wouldn't expect life to exist, but we know that they can because we found them. If we make conclusions that we cannot find life on Titan, then we never will because we won't be looking. Life could be thriving on Titan, but we won't know unless we look for ourselves. Also, for all we know, Titan's oceans are loaded with organic compounds that are don't originate from the surface. We don't know what the actual internal structure of Titan looks like because we lack the data.

mbauman 3y ago
Yeah, that's not at all what the actual journal article claimed. It starts super simple: We know Titan has two things that seem so promising for life as we know it! Organic compounds on the outside, liquid water on the inside. And then it asks: Might those two promising things meet? Other work hasn't found the tectonics that would do it; could cratering do it? And that very particular answer is pretty definitively no.
thriftwy 3y ago
Titan is likely habitable for life as we know it. It's hard to imagine why Titan won't have life around hydrothermal vents and the like.

andrewstuart 3y ago

Is there anyone on Earth who thinks it might have been habitable, at -292 degrees Fahrenheit (-180 degrees Celsius). Its weird that there's any narrative at all around this.

StanislavPetrov 3y ago
There is a massive ocean of liquid water, which indicates that it is substantially warmer than that.
dang 3y ago
"Please don't post shallow dismissals, especially of other people's work. A good critical comment teaches us something." https://news.ycombinator.com/newsguidelines.html https://news.ycombinator.com/newsguidelines.html
margalabargala 3y ago
There's a theory that life on Earth began at extremely cold temperatures, yes; below -100F. https://www.discovermagazine.com/planet-earth/did-life-evolve-in-ice https://www.discovermagazine.com/planet-earth/did-life-evolv... It's only Titan's surface that is at -292F, anyway, The theory is that life, if it exists, would be present in the subsurface ocean, which would be significantly warmer.
- mr_toad 3y ago
  Actually there is speculation that methane or ethane based life could exist on the surface.
  - margalabargala 3y ago
    Sure, there is "speculation" about pretty much anything and everything. There's speculation that quantum flux based life could exist on the surface of the sun. The speculation that is based on things we already know to be possible, speculates that life could be possible in the subsurface ocean.

dougmwne 3y ago

This doesn’t seem to be a very meaningful theory to draw conclusions about life. We have no idea how much carbon is already present in Titan’s ocean and if there’s need for a water cycle that connects to the surface. Also this study only considers impact craters, not surface tectonics. And there could be plenty of carbon sources from ocean floor interactions.

margalabargala 3y ago
The journal authors agree with you. The "most likely uninhabitable" conclusion is an invention of the popsci article's author. The actual article's conclusion is basically "for there to be life on Titan, there needs to be more carbon in the ocean than would be transferred solely by surface impactors". It absolutely does not rule out the existence of those carbon source.
- thereddaikon 3y ago
  As usual, the reporting on science ends up distorting or even inventing conclusions out of thin air.
  - margalabargala 3y ago
    To quote the two concluding sentences of the journal article: > It is unlikely that the calculated ﬂuxes are sufﬁcient to maintain a detectable biosphere, unless the thickness of organics on Titan’s surface is greater than currently estimated, abundant biomolecules are available from Titan’s rocky core, or surface biomolecules can be delivered to the ocean by a process other than impact. Our calculations suggest that despite Titan being the most organic-rich ocean world in the Solar System, this does not automatically imply an organic-rich and habitable ocean.
  - shiroiushi 3y ago
    I feel like science reporting would actually be greatly improved if they simply had ChatGPT write the articles. The human "reporters" they have now are terrible.

JoeAltmaier 3y ago

Perhaps a historical impact could have been large enough to seed the ocean.

andrewflnr 3y ago

The abstract of the actual paper only claims: > Unless biologically available compounds can be sourced from Titan's interior, or be delivered from the surface by other mechanisms, our calculations suggest that even the most organic-rich ocean world in the Solar System may not be able to support a large biosphere. Which is much less sensationalist, to put it politely.

arp242 3y ago
Which is just a different way of saying "uninhabitable". The middle of the Sahara is uninhabitable. Unless you introduce sufficient water and plants that is.
- andrewflnr 3y ago
  It is not "just a different way". There's no reason to assume impact melting from the surface is the only source of carbon in Titan's ocean. The authors of the study seem clear on this. I don't know why you feel the need to stand up for phys.org on this, or why you think the Sahara is relevant.
- lucb1e 3y ago
  Except, if I understand them correctly: they don't know what the Sahara's core is made of and might supply for life, to keep the analogy Not that that makes it likely to be hospitable. I'm only surprised by the headline because I wouldn't have thought anyone had expected anything different, so a headline like "as uninhabitable as you might figure" would have made more sense, but nevertheless this doesn't rule it out to about the same extent as it wasn't deemed unlikely already in my perception (as a follower of space news)
- BirAdam 3y ago
  Well… the Sahara has life though. It isn’t abundant, but it’s certainly there.
  - andrewflnr 3y ago
    Indeed, there's quite a gulf between not having "a large biosphere" and having no biosphere at all.

pvaldes 3y ago

> One elephant per year of glycine into an ocean 12 times the volume of Earth's oceans is not sufficient to sustain life". This reasoning is too limited IMAO. Titan oceans may not have whales, but for sure could still afford a lot of animals. 1) It seems that Titan has been there since the early phases of solar system creation, so I'll assume that is older than 3 billions of years (to pick a conservative value). One elephant a year for 3 billions of years is still a lot. 2) Titan could have been bombed with much more matter on the early phases of solar system history. 3) Live on earth is perfectly able to cope with a poor nutrient aquatic environment. Most of the earth falls exactly on this category after all. 4) Some life forms need just a little bit of carbon to be functional. Earth has very big animals that are 99% water. 5) Cold water promotes slow metabolism. Life just adapts growing really slow, being carried by currents, and adopting a poiquiloterm life style.

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nearbuy 3y ago
Though it's not clear from the article, I think they aren't concerned about the physical material. This organic matter could be an energy source for life and they're saying that it's not enough energy. Even if a lot of stored energy had accumulated, it's not sustainable, and life exhibits exponential growth when food is plentiful.
- pvaldes 3y ago
  If the water on Titan is liquid [1], by definition some source of energy is warming it over zero Celsius degrees. And if there are huge oceans of liquid water, the source of energy somewhere must be huge also. This is all that life needs to thrive. Entire ecosystems on Earth developed at high pressures, close to catastrophic scorching temperatures, without the need of any sunlight or photosynthesis, just using chemical energy from hydrothermal vents. This does not prove that Titan has life, but life has proven several times that can flourish in such circumstances. I'm not an astrobiologist and can miss essential details about the moon, but in my opinion being isolated under a several km layer of ice, with cold and absolute obscurity, does not prevent life on Titan at all, because it didn't prevented it on Earth. Bioluminiscence still ranks among the more common methods of communication on Earth. [1] (Having salt on the water could help a lot with that liquid state. I assume that we could find easily several layers of saltwater and also methane) But after some good replies above, it seems that the real question here is not "if the water is liquid" as much as "if the liquid is water". That changes the game totally.

vel0city 3y ago

This is talking about estimated average comet/asteroid impacts, right? If we're going by the average asteroid impacts on even million-year timescales causing radical changes to a heavenly body, we'd end up with no moon. I definitely get this is a limited research here, and I'm not faulting it for that. Its good to know it seems like this kind of cycle wouldn't be consistent in adding organic molecules to the subsurface oceans. But let's not necessarily see this as "there's no way organic molecules could have been pushed down in relevant amounts."

deadbabe 3y ago

Uninhabitable as in we couldn’t introduce basic life forms there even if we tried?

animal531 3y ago
I'm sure we could introduce some extremophiles. Here on Earth we have organisms living anywhere, including inside of rocks!

gweinberg 3y ago

The article seems to treat speculation with more confidence than it deserves, and also to report estimates with unjustified level of precision. For example, it claims the annual amount of glycine transferred to Titan is equal to the mass of "a male African elephant" rather than simply an elephant.

fnordpiglet 3y ago
I always find the metaphorical estimates in science reporting absurd. I don’t know why the mass of a male African elephant is in any way more visceral than 6000 kg (btw a quick google search gives a band of 1800 to 6300kg, which isn’t particularly precise). Given Titan is about 4.5 billion years old this could be an enormous amount of complex carbon transferred from the surface assuming it’s more or less a one way process.

ramesh31 3y ago

There's always Europa

skirmish 3y ago
“ALL THESE WORLDS ARE YOURS – EXCEPT EUROPA. ATTEMPT NO LANDING THERE.”

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aaroninsf 3y ago

Saw this lack week and frankly I don't know why it's getting attention. Alright, I suppose I do actually. Its right up there with Fermi paradox papers wrt the number of wide and wild assumptions required to justify a dramatic headline and clickbait-ha-ha measurement like "one elephant." It's a reasonable hypothesis, but despite the drama, this sort of thing has no predictive power in our actual universe. Only one where those assumptions all hold. Could be ours. Probably not though.

slater 3y ago

Europa it is, then! Were there any warnings about landing there?

robertlagrant 3y ago
I know it's not what you're referring to, but I just watched something even more on the nose![0] [0] https://www.imdb.com/title/tt2051879 https://www.imdb.com/title/tt2051879

perihelions 3y ago

- "These fluxes suggest an upper limit for biomass productivity of ∼10³ kgC/year from a glycine fermentation metabolism." This is really an upper bound on accessible energy (the "carbon" explanation in the press office release is hand-wavey). The idea is that solar photochemistry in Titan's atmosphere creates chemical energy gradients, in the form of energetic compounds like that glycine; and these energy gradients could migrate through the ice and support a biosphere in the subsurface ocean. The abstract* says that, actually, very little of that energy gradient can get through the ice shell. This situation is different from that of some of the other icy moons: they potentially have much larger geochemical energy sources, from chemical reactions between the water ocean and primordial rock. The problem with Titan is it (probably) has a weird ice shelf on the bottom of its underground ocean, which isolates it from rock. So rock-ocean weathering probably doesn't happen there. * (The paper's not on arXiv or SciHub if you were wondering)

kurthr 3y ago
Of course one could say the same about oil, coal, and gas on the earth. We're burning a 100 million years of bio productivity. Any such bio productivity could have been occurring and being stored on Titan for 10^8 years as well. It might not be sustainable. I don't know.

BirAdam 3y ago

No matter the estimation, no matter the probability, the history of scientific inquiry has shown that reality is weirder than the wildest of human imaginings. Let’s just go and find out for sure, and maybe write less clickbait, yeah?

alberth 3y ago

TIL: that some moons have atmospheres. https://futurism.com/the-atmospheres-on-our-moons https://futurism.com/the-atmospheres-on-our-moons

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Freedomboy 3y ago

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matt3210 3y ago

Replace “life” with “life as we know it”

DoreenMichele 3y ago

Life as we know it here on Earth... Water, carbon, etc. I heard eons ago that Spock's green blood was inspired by the blue-green blood of horseshoe crabs which has a copper-based system instead of iron, among other oddities: A horseshoe crab's blood has a blue to blue-green color when exposed to the air. The blood is blue because it contains a copper-based respiratory pigment called hemocyanin. https://dnr.maryland.gov/ccs/Pages/horseshoecrab-medical.aspx https://dnr.maryland.gov/ccs/Pages/horseshoecrab-medical.asp... Though this piece contradicts that origin story: https://www.mentalfloss.com/article/578911/why-star-treks-mr-spock-has-green-blood https://www.mentalfloss.com/article/578911/why-star-treks-mr... I'm failing to come up with the right search terms to find what I recall about zooplankton and the oceanic food web. It differs from other food webs and this shows up starkly in certain kinds of charts/models. Zooplankton are tiny creatures found in relatively small amounts on the surface but breed like crazy and feed huge animals, including some types of whales. So where other food webs are kind of pyramidal and you have a huge amount of plants at the base of the web and a smaller amount of animals that eat those plants and a smaller mass of animals that eat those animals, the ocean's food web doesn't follow a similar pattern. It's not pyramidal. There is much more mass found in other layers of the food web than of zooplankton at any given time. (Included because of the claim that "One elephant per year of this substance can't sustain life..." How do we know that?) Furthermore, on Earth we have life sustained by undersea volcanoes which defies our usual patterns of life. I'm out of my depth on exactly how these lifeforms differ from the norm on Earth, so I won't try to give a nutshell version of how they differ, but here are some links: https://oceantoday.noaa.gov/underwatervolcanoes/ https://oceantoday.noaa.gov/underwatervolcanoes/ https://www.mpg.de/19982028/0309-mbio-life-in-the-smoke-of-underwater-volcanoes-154772-x https://www.mpg.de/19982028/0309-mbio-life-in-the-smoke-of-u... https://en.wikipedia.org/wiki/Sulfurimonas https://en.wikipedia.org/wiki/Sulfurimonas That's what I know as a former homeschooling mom and Earthbound human who reads. Surely we can do a little better than "It doesn't readily match the patterns of the dominant lifeforms of this planet, so we cannot imagine that some other planet with dramatically different chemical makeup and other details has lifeforms that are fundamentally different from that, and never mind that Earth has some oddities living on it." Cue the plot from the Star Trek episode where humans were being attacked by the guardian of the eggs that they were destroying willy-nilly without realizing they were eggs: https://en.wikipedia.org/wiki/The_Devil_in_the_Dark https://en.wikipedia.org/wiki/The_Devil_in_the_Dark

ssijak 3y ago

There are so many variables that I am not sure that they can conclude anything substantial like they are trying based on this calculation alone. Titan is old 4 billion years. That alone is enough to not be able to conclude that its oceans are poor in organics. So many things could have happened during the evolution of Titan during those 4 billion years that we just don't know about. Plus what about mixing from under the oceans. I vote for sending meaningful probes as soon as we have tech for it. I dream of an era where humanity will spend 1 trillion per year on exploratory space tech and not on war machinery.

shiroiushi 3y ago
>I vote for sending meaningful probes as soon as we have tech for it. I dream of an era where humanity will spend 1 trillion per year on exploratory space tech and not on war machinery. What if your peaceful probe starts an interplanetary war with the inhabitants of those oceans?

omneity 3y ago

I found the language in this article to be very strong and it seems to me this discovery only rules out a specific glycine exchange mechanism to power life reactions. The paper contrastingly is rather descriptive and much less assertive, and doesn’t jump to the same conclusions the article is pushing. You would expect this from a tabloid headline rather than Phys.org.

southernplaces7 3y ago

While we have no idea what kinds of landscapes and terribly esoteric environments life in some form could endure (since our only basis for comparison is the flora and fauna of our own evolutionary tree), I always though it was absurd to assume life on Titan just because it has water. The conditions out by the orbit of Saturn are hellish, even for a body of water protected by a vast surface shield of hard material.

hoseja 3y ago
Says the guy made of hydric acid, currently submerged in vast pool of molecular oxygen.
- southernplaces7 3y ago
  touche! But more seriously, an interesting project would be to simulate the conditions of our solar system's "candidate" for life ecosystems in laboratory conditions as precisely as we can based on known information, and then subject some of the toughest microorganisms we have living on earth to them, to see if at least they could survive or even thrive. For example: recreate conditions of pressure, cold, radiation and chemical composition like those we think are the case in Titan's subterranean ocean, and then see how well a colony of water bears (tardigrades) endures. Seems a lot more practical then speculating. I'm curious if this has been done in a systematic way by any organization on Earth.

hoseja 3y ago

JFC, water-carbon chauvinism again.

matthewfelgate 3y ago

The NASA Dragonfly project to Titan looks very interesting.