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.
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.
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.
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.
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
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.
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.
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.
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.
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/
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.
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.
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
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.
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."
and yet, it dies after 1 week when I bring it in as a houseplant
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.