One wonders where else in the solar system moss from Earth may have taken hold. Spores and such could be making the journey randomly from gravity well to gravity well.
Moss requires quite a bit of liquid water to actually reproduce, since (IIRC) their sperm need to swim around to mate. So we're left with, like, maybe Europa, if there's enough light and enough water gets into the surface via cracks? I doubt there's enough light under the surface, even if you found a moss species that can survive being totally submerged in whatever saltwater hellscape is under there. Basically there are still going to be huge problems for moss anywhere besides Earth. They already mostly stick to wet environments here.
>A Martian meteorite is a rock that formed on Mars, was ejected from the planet by an impact event, and traversed interplanetary space before landing on Earth as a meteorite.
Sphere's surface grows as radius squared, but volume grows as radius cubed. Hence a small terrarium will quickly freeze, and a huge terrarium will eventually fry. There is an optimal size for a terrarium, given its orbit, that keeps its internal temperature within the habitable range.
Also it would need many more plants than animals. I would rather go with an aquarium.
That's not how space or terrariums work. A terrarium does not spontaneously produce energy out of nothing, it gets energy from the sun. Heat input from the sun is proportional to cross sectional area, while heat loss to space is proportional to surface area, which scale the same for a sphere. A larger object will have more thermal mass which would make it take longer to change its temperature, but it will still have the same thermal equilibrium. Terrariums do not need to be spheres, so the volume does not necessarily scale as the radius cubed.
I imagine one like that in my kitchen which is currently moss, a succulent, and some weed that happened to germenate. All three are alive after two years so far. The bottom is rocks and soil. There's a clear water cycle too as water evaporates and collects on the surface of the glass and then drips down.
Heat isn't produced by the volume. Heat may be produced by something within the volume, but it's not the volume's existence that causes heat to be produced. There is no fundamental reason a bigger terrarium should produce more heat, nonetheless that heat production should be directly proportional to volume.
Yes, obviously it'd be the stuff in the terrarium rather than the space it occupies that produces heat, but the amount of stuff you can fit in it is determined by the occupiable space. And if that stuff is producing heat, such as by decay, there's going to be more heat with more stuff. Though even if it cooks itself for a while, it should eventually settle on a temperature determined mostly by orbital parameters and material properties rather than size, since the stuff can't be net exothermic forever. But greater atmospheric depth probably still increases equilibrium temperature by reducing heat transfer through that side of the terrarium.
> but the amount of stuff you can fit in it is determined by the occupiable space.
You can fit more into a larger terrarium, but that doesn't require a larger terrarium to contain more. Regardless of what is contained within the terrarium, it's heat production is limited by what it receives from the environment.
> But greater atmospheric depth probably still increases equilibrium temperature by reducing heat transfer through that side of the terrarium.
Greater atmospheric depth affects heat transfer by changing the density of the atmosphere, which is relevant for an atmosphere held to a body by gravity, but not for one contained in a pressurized vessel like a terrarium. A terrarium with a 1 atm internal pressure has an atmosphere depth equal to earth's atmosphere regardless of size (at least up until the point where the terrarium's gravity is comparable to a planet).
I am me and I approve this message. The habitats, the people, the robots, and a beautiful theme song by the great Joan Baez. Silent Running is a great film indeed.
The other side would radiate, losing the heat. Earth, being in a similar position, is neither incinerated nor refrigerated, though different sides of it can be hot or cold.
Depending on how rich in internal radioactive sources of heat it isn't scale free with mass. Larger masses of the same makeup will reach different thermal equilibrium since the surface area grows at a slower rate than the internal heat production from decay which scales with mass.
I don't know if it is significant, but tidal sources of heat might not scale the same either.
At least during emergence of life there was the faint young sun + higher proportions of radioactive elements, so could have made up 0.2% of outgoing thermal radiation or so on earth (ignoring outflow of residual heat from early collisions). I think 5-10 earth masses is the limit for terrestrial planets, and you can imagine having say 10x more radioactive elements and still hospitable to life, rather than being made of solid uranium. So maybe double digit percentage radiant heat outflow differences between very small and very large on those.
Presumably a spherical ball of air would be able to transfer heat more quickly (from the hot to the cold side) than the same volume spread out as a very thin hollow layer.
So... Now we have a way to commit an act of biological terrorism on the whole Milky Way? Just get a hundred of tons of moss spores to space and accelerate them in all direction to spread them all over Milky Way. It is somehow a very satisfying thought. Maybe I'm a born terrorist deep down, and just didn't get the chance to become one?
While spores seem hardened against the extremes of space, we haven’t shown that any of this hardy life is capable of colonizing a barren world. It seems like all life on Earth depends on some already functioning biosphere. In other words, even if we sent tardigrades to a world with oxygen and liquid water, what would they eat? Where would they get nutrients such as vitamin B? All the vitamin B we consume is created by bacteria, no animal produces it on its own. So we would have to send thousands of interdependent species. And I’m willing to bet the majority of them aren’t nearly as hardy.
Sending spores to a planet that already has life might work. But I can’t help but think whatever life we introduce would be at a disadvantage. Maybe life on that planet never incorporated certain proteins, vitamins, or amino acids and whatever we send just ends up getting scurvy and dies out.
Well, plants famously don't eat much more than sun light, water and carbon dioxide. Otherwise they just need phosphorus, nitrogen and some trace elements.
Moss has already adapted to barren environments. Its niche is growing where nothing else grows. Like, on top of rock. It's not having roots, not mingling with modern temptations in the soil. Most mosses actually aren't doing well in competitive, complex ecosystems full of nutrients and such.
While animals could never live by themselves, some autotrophic bacteria can.
A community of several different kinds of bacteria would have better chances than a single species, but for bacteria there is certainly no need for thousands of species.
Autotrophic bacteria would need only an environment providing less than 20 essential chemical elements (most of which belong to the most abundant elements, a notable exception being molybdenum) and either solar light for energy, neither too little nor too much, or a chemical source of energy, like dihydrogen + carbon dioxide, which can be provided by volcanic gases or by the reaction of water with volcanic rocks.
There would have been many places in the Solar System suitable for bacteria, except that where there is water, it is usually too cold, and where it is not too cold, there is no water.
For a photosynthesizer minerals water, sun and co2 should be enough I think? Maybe oxygen is needed too unless it's able to store oxygen for respiration. Now eventually it might start running out of some resource or building up toxic levels off something so you gotta hope that that happens slow enough that evolution is in time to fix those issues.
you missed something, in that it is impossible to get perfectly sterile living animals or plants, and all* of them are carrying a large vaiety of bacteria, viruses, spores, and other animals eggs, etc.
everything is an inoculant
* I am aware of various experiments that did attempt to raise animals in perfectly sterile environments, where they died, but the only way to sterilise and maintain sterility, are extream, and largely impossible while keeping any single lifeform, alive.ie: it is far from the default
The sheer number of civilizations, that it is normally believed there is in the Milky Way, pretty much guarantees that some of them, some of the time, do exactly this. For whatever alien reasons they might have. The Milky Way should be drizzling with moss spores already, or whatever exobiological life that can survive interstellar conditions.
My definition of terrorism was always more in the lines of destroying life, not spreading it. Life might be very rare, even possible that life only developed here .. then our job might be exactly this, find ways to spread life.
> My definition of terrorism was always more in the lines of destroying life, not spreading it
When you come to some place and change it drastically, is it a good thing or a bad thing? I don't think it is. There are some excuses that I can accept, but if you do it "just for fun" of it, I think it is an evil deed.
Places have their own history, their own shapes and forms, and then someone comes and wipes it off just because they can. It cannot be Good, can't it?
You talk about dead stones as if they have life. But they are dead. Spreading life is for fun in a way, that without life there is no fun at all. Just nothing, dead matter. (unless you believe in animism)
Spreading foreign life that kills local life (even if by just out-competing on resources) sounds a bit like terrorism though.
But I have hard time believing even hardened organisms like moss or tardigrades could survive millions of years of hard vacuum and extreme cosmic radiation. Maybe embedded in some properly protective envelope, 1 out of billion trillion might. And then that one has 1 out of billion billion trillion chance to land eventually on a place that could be called livable. Or add few extra zeroes.
It's pretty difficult to accelerate hundreds of tons (or even a lot less than that) of stuff out of the gravity well of the Sun. Let's start by terrorising things a bit closer to home (the moon, Mars)
Any idea that Earth-bound life need to migrate to outside of Earth, is a stupid sales talk, good for selling fiction stories. Any research work in this direction is purely to protect the jobs, work and funding.
Better source: https://www.theguardian.com/science/2025/nov/20/moss-spores-...
Link to the research article:
https://www.cell.com/iscience/fulltext/S2589-0042(25)02088-7
The link provided in The Guardian is broken.
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Finally we know how to expand into the universe - just send that moss out there!
I always thought this was peak exo-earth evolution though:
https://www.youtube.com/watch?v=4SK0cUNMnMM
Would be interesting to see what sorts of motile creatures could descend from mosses in a few hundred million years.
But how does it taste? Safe to assume in 1000 years we'll have moss farms thriving in orbit.
No one even knows complex societies are going to survive 2C of warming.
We should shoot life towards any planet in the solar system..
Earth is already exchanging material with other bodies constantly. So there is a chance that it is already happening.
Fulfilling our purpose as an rna based von Neumann machine.
probably not to mars, europa, ganymede, or enceladus though
One wonders where else in the solar system moss from Earth may have taken hold. Spores and such could be making the journey randomly from gravity well to gravity well.
Moss requires quite a bit of liquid water to actually reproduce, since (IIRC) their sperm need to swim around to mate. So we're left with, like, maybe Europa, if there's enough light and enough water gets into the surface via cracks? I doubt there's enough light under the surface, even if you found a moss species that can survive being totally submerged in whatever saltwater hellscape is under there. Basically there are still going to be huge problems for moss anywhere besides Earth. They already mostly stick to wet environments here.
A mechanism by which this could happen:
>A Martian meteorite is a rock that formed on Mars, was ejected from the planet by an impact event, and traversed interplanetary space before landing on Earth as a meteorite.
https://en.wikipedia.org/wiki/Martian_meteorite
Fred Hoyle with Chandra Wickramasinghe have posited mechanisms for such events in their model of Panspermia
I always wonder what would happen if you put a fully enclosed glass terrarium in space. How would it fair. Not big either. Grape fruit sized.
Sphere's surface grows as radius squared, but volume grows as radius cubed. Hence a small terrarium will quickly freeze, and a huge terrarium will eventually fry. There is an optimal size for a terrarium, given its orbit, that keeps its internal temperature within the habitable range.
Also it would need many more plants than animals. I would rather go with an aquarium.
That's not how space or terrariums work. A terrarium does not spontaneously produce energy out of nothing, it gets energy from the sun. Heat input from the sun is proportional to cross sectional area, while heat loss to space is proportional to surface area, which scale the same for a sphere. A larger object will have more thermal mass which would make it take longer to change its temperature, but it will still have the same thermal equilibrium. Terrariums do not need to be spheres, so the volume does not necessarily scale as the radius cubed.
I imagine one like that in my kitchen which is currently moss, a succulent, and some weed that happened to germenate. All three are alive after two years so far. The bottom is rocks and soil. There's a clear water cycle too as water evaporates and collects on the surface of the glass and then drips down.
What does volume have to do with energy balance?
Heat is transferred through the surface area and produced by the volume (assuming there's something going on in the system that's exothermic).
Heat isn't produced by the volume. Heat may be produced by something within the volume, but it's not the volume's existence that causes heat to be produced. There is no fundamental reason a bigger terrarium should produce more heat, nonetheless that heat production should be directly proportional to volume.
Yes, obviously it'd be the stuff in the terrarium rather than the space it occupies that produces heat, but the amount of stuff you can fit in it is determined by the occupiable space. And if that stuff is producing heat, such as by decay, there's going to be more heat with more stuff. Though even if it cooks itself for a while, it should eventually settle on a temperature determined mostly by orbital parameters and material properties rather than size, since the stuff can't be net exothermic forever. But greater atmospheric depth probably still increases equilibrium temperature by reducing heat transfer through that side of the terrarium.
> but the amount of stuff you can fit in it is determined by the occupiable space.
You can fit more into a larger terrarium, but that doesn't require a larger terrarium to contain more. Regardless of what is contained within the terrarium, it's heat production is limited by what it receives from the environment.
> But greater atmospheric depth probably still increases equilibrium temperature by reducing heat transfer through that side of the terrarium.
Greater atmospheric depth affects heat transfer by changing the density of the atmosphere, which is relevant for an atmosphere held to a body by gravity, but not for one contained in a pressurized vessel like a terrarium. A terrarium with a 1 atm internal pressure has an atmosphere depth equal to earth's atmosphere regardless of size (at least up until the point where the terrarium's gravity is comparable to a planet).
Is there a 'just right' size that neither freezes nor fries?
About Earth sized, I think. A bit bigger if the soil is low on hot isotopes.
Giant terrariums in space was the premise of one of the great science fiction films of the early 1970s: Silent Running
https://cult-scifi.com/silent-running-1972-movie/
I am me and I approve this message. The habitats, the people, the robots, and a beautiful theme song by the great Joan Baez. Silent Running is a great film indeed.
If it was in the sun it would be incinerated and in the shade it would freeze right?
The other side would radiate, losing the heat. Earth, being in a similar position, is neither incinerated nor refrigerated, though different sides of it can be hot or cold.
Earth has the benefit of a thermal mass that's at least a couple times larger than your average terrarium.
Everything exposed to the sun will heat up until the energy it emits balances out the incoming energy.
Being a larger mass just means an object will take longer to heat up.
Depending on how rich in internal radioactive sources of heat it isn't scale free with mass. Larger masses of the same makeup will reach different thermal equilibrium since the surface area grows at a slower rate than the internal heat production from decay which scales with mass.
I don't know if it is significant, but tidal sources of heat might not scale the same either.
I think we can safely say the planet made of uranium is an edge case.
The Earth's internal radioactivity is a miniscule energy source compared to the sun.
Yes it's small, but:
At least during emergence of life there was the faint young sun + higher proportions of radioactive elements, so could have made up 0.2% of outgoing thermal radiation or so on earth (ignoring outflow of residual heat from early collisions). I think 5-10 earth masses is the limit for terrestrial planets, and you can imagine having say 10x more radioactive elements and still hospitable to life, rather than being made of solid uranium. So maybe double digit percentage radiant heat outflow differences between very small and very large on those.
Presumably a spherical ball of air would be able to transfer heat more quickly (from the hot to the cold side) than the same volume spread out as a very thin hollow layer.
Interesting point.
So... Now we have a way to commit an act of biological terrorism on the whole Milky Way? Just get a hundred of tons of moss spores to space and accelerate them in all direction to spread them all over Milky Way. It is somehow a very satisfying thought. Maybe I'm a born terrorist deep down, and just didn't get the chance to become one?
While spores seem hardened against the extremes of space, we haven’t shown that any of this hardy life is capable of colonizing a barren world. It seems like all life on Earth depends on some already functioning biosphere. In other words, even if we sent tardigrades to a world with oxygen and liquid water, what would they eat? Where would they get nutrients such as vitamin B? All the vitamin B we consume is created by bacteria, no animal produces it on its own. So we would have to send thousands of interdependent species. And I’m willing to bet the majority of them aren’t nearly as hardy.
Sending spores to a planet that already has life might work. But I can’t help but think whatever life we introduce would be at a disadvantage. Maybe life on that planet never incorporated certain proteins, vitamins, or amino acids and whatever we send just ends up getting scurvy and dies out.
Well, plants famously don't eat much more than sun light, water and carbon dioxide. Otherwise they just need phosphorus, nitrogen and some trace elements.
Moss has already adapted to barren environments. Its niche is growing where nothing else grows. Like, on top of rock. It's not having roots, not mingling with modern temptations in the soil. Most mosses actually aren't doing well in competitive, complex ecosystems full of nutrients and such.
While animals could never live by themselves, some autotrophic bacteria can.
A community of several different kinds of bacteria would have better chances than a single species, but for bacteria there is certainly no need for thousands of species.
Autotrophic bacteria would need only an environment providing less than 20 essential chemical elements (most of which belong to the most abundant elements, a notable exception being molybdenum) and either solar light for energy, neither too little nor too much, or a chemical source of energy, like dihydrogen + carbon dioxide, which can be provided by volcanic gases or by the reaction of water with volcanic rocks.
There would have been many places in the Solar System suitable for bacteria, except that where there is water, it is usually too cold, and where it is not too cold, there is no water.
For a photosynthesizer minerals water, sun and co2 should be enough I think? Maybe oxygen is needed too unless it's able to store oxygen for respiration. Now eventually it might start running out of some resource or building up toxic levels off something so you gotta hope that that happens slow enough that evolution is in time to fix those issues.
Think fewer cells. Like one.
you missed something, in that it is impossible to get perfectly sterile living animals or plants, and all* of them are carrying a large vaiety of bacteria, viruses, spores, and other animals eggs, etc. everything is an inoculant
* I am aware of various experiments that did attempt to raise animals in perfectly sterile environments, where they died, but the only way to sterilise and maintain sterility, are extream, and largely impossible while keeping any single lifeform, alive.ie: it is far from the default
Is it 100% certain that's not how they got here in the first place?
Goldilocks theory is pretty interesting
The sheer number of civilizations, that it is normally believed there is in the Milky Way, pretty much guarantees that some of them, some of the time, do exactly this. For whatever alien reasons they might have. The Milky Way should be drizzling with moss spores already, or whatever exobiological life that can survive interstellar conditions.
My definition of terrorism was always more in the lines of destroying life, not spreading it. Life might be very rare, even possible that life only developed here .. then our job might be exactly this, find ways to spread life.
> My definition of terrorism was always more in the lines of destroying life, not spreading it
When you come to some place and change it drastically, is it a good thing or a bad thing? I don't think it is. There are some excuses that I can accept, but if you do it "just for fun" of it, I think it is an evil deed.
Places have their own history, their own shapes and forms, and then someone comes and wipes it off just because they can. It cannot be Good, can't it?
You talk about dead stones as if they have life. But they are dead. Spreading life is for fun in a way, that without life there is no fun at all. Just nothing, dead matter. (unless you believe in animism)
You're wrong for many reasons, and I have no sense of humor.
The latter is your problem I guess, but I am interested in the reasons why you think I am wrong.
I don't, at all. I thought it was a funny response to state the obvious: that terrorism is about killing, not spreading life.
Sure, but some forms of it - like weaponized anthrax - do both.
(And terrorism is often more about causing fear than raw death counts.)
Spreading foreign life that kills local life (even if by just out-competing on resources) sounds a bit like terrorism though.
But I have hard time believing even hardened organisms like moss or tardigrades could survive millions of years of hard vacuum and extreme cosmic radiation. Maybe embedded in some properly protective envelope, 1 out of billion trillion might. And then that one has 1 out of billion billion trillion chance to land eventually on a place that could be called livable. Or add few extra zeroes.
To kill local life, it first must exist, which is not confirmed at all. And if it exists, it is likely way better adopted to the local conditions.
In genetal, nature works with small chances, look how many seeds a plant gives and how few of them will be a new plant.
(Or how many sperms are created for 1 human)
But sure, chances here are way, way lower.
It's pretty difficult to accelerate hundreds of tons (or even a lot less than that) of stuff out of the gravity well of the Sun. Let's start by terrorising things a bit closer to home (the moon, Mars)
A bootstrap station that can turn asteroids or space dust into probes sounds like a solution for that.
"Life on our planet was a delight, until the day the moss came."
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Let’s put this on mars asap
and yet, it dies after 1 week when I bring it in as a houseplant
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Any idea that Earth-bound life need to migrate to outside of Earth, is a stupid sales talk, good for selling fiction stories. Any research work in this direction is purely to protect the jobs, work and funding.