The habitable epoch, when "the cosmic microwave background (CMB) had a temperature of 273–373 K (0–100 °C), allowing early rocky planets (if any existed) to have liquid water chemistry on their surface and be habitable, irrespective of their distance from a star," has always fascinated me [1]. Space itself was room temperature.
Our universe would seem to them like the universe on the verge of heat death does to us. To my knowledge, I don't know of any fiction that explores this setting--it's on my bucket list to write.
Not strictly an answer to your question regarding the math, but the video I linked above does mention an estimate for how long the period might have been.
Why does an asteroid have to hit the earth? Life is constantly being shed from the upper atmosphere into space right now. As we travel through space we leave a plume of life behind us. Certainly almost none of it survives, but almost isn’t none, and a lot of life spreads as hardened spores that can withstand extreme conditions until more favorable conditions present and they “wake up.”
> Life is constantly being shed from the upper atmosphere into space right now. As we travel through space we leave a plume of life behind us.
Can you point to any source for that? I've never heard of such a thing and can't find anything from a quick online search supporting that idea. Everything I read is that gravity will pull back any bacteria that get to the outer edges of the atmosphere, which makes sense because they'd need to have some force stronger than gravity to escape.
What information can you point to that supports the idea that we leave a "plume of life behind us"?
I think the idea behind an asteroid is that only something with that level of force could eject bacteria that could overcome the Earth's gravity to escape.
Edit: atmospheric escape [1] is a well-known phenomenon, but that's exclusively about gases, at the molecular level. It doesn't mention anything about bacteria, which are of course massive in comparison -- the factors that can cause a single atom or molecule to gain enough energy to escape gravity don't apply to things the size of bacteria.
The chance of a particle escaping depends on its mass.
That's why helium escapes pretty fast. The other gas molecules still escape, but far far slower. The Maxwell Boltzmann distribution applies.
Something like a virus is far far heavier again, so the rate of escape would be miniscule. Not sure if it's small enough to have never happened across the surface of earth though.
One of the main ideas explained in this video is that the very early universe (i.e. the universe “right after the Big Bang” in cosmic timescales) might have been habitable for a short period of time. During this time window, the right temperature to support life wouldn’t have been restricted to the proximity of stars, but would have instead taken place absolutely everywhere in space due to the intrinsic temperature of the universe itself.
> The second one is an observation about the rate at which the different genomes on Earth have changed over evolutionary history. When extrapolated back into the past, this evolution rate of genomes suggests that the current lineage of life on Earth might be at least 10 billion years old,
I wonder to what extent the scientists who study these evolutionary clocks are able to factor in increasingly (or decreasingly) capable DNA replication and repair mechanisms. More faithful DNA replication and repair would artificially show a slower rate of genome evolution.
We often think about life arising in one location and then spreading across the galaxy or universe. Quite interesting to consider instead life arising everywhere and then being reduced to only a few (maybe one) remaining pockets across the entire universe, or not at all.
Of course that likely doesn’t apply to life as we know it, assuming our estimates of the age of the sun and the universe are correct.
My understanding is the time when the universe was at life supporting temperatures, was long before the formation of the first stars and fusion of heavier atoms than hydrogen.
It is hard to imagine life without a large variety of atoms.
> the time when the universe was at life supporting temperatures, was long before the formation of the first stars and fusion of heavier atoms than hydrogen
Stars with rocky planets during the habitable epoch "lie ∼8.5 standard deviations (σ) away on the exponential tail of the Gaussian probability distribution of initial density perturbations," though "their abundance could have been significantly enhanced by primordial non-Gaussianity."
Interesting! It Sounds like the paper supports my statement as a generalization, but explores extreme outliers in stellar formation.
It sounds like there is a chance some atomic fusion could have occurred at this time, but It would be isolated to a few instances in our light cone. This is a pretty different than the entire universe awash in favorable conditions to life.
> Terence McKenna's theory was that human intelligence stems from psilocybin-containing mushroom spores
The Stoned ape theory "has largely been rejected by the scientific community, who cite numerous alleged discrepancies within his theory and claim that his conclusions were arrived at via a fundamental misunderstanding of Fischer's studies" on "psychedelic drugs, schizophrenia, the perception-hallucination continuum model of altered states of consciousness, and...gustation" [1][2].
After the big bang, there was likely many millions of years where the universe was a comfortable temperature that would have allowed life to evolve there first. Which eventually cooled and died out until it met the right conditions. Probably why space smells like burnt food "Other astronauts have described it in similar yet varying ways: "burning metal," "a distinct odor of ozone, an acrid smell," "walnuts and brake pads," "gunpowder" and even "burnt almond cookie." " https://science.howstuffworks.com/space-smell.htm#:~:text=Ot...
"electrical smell", "burnt almond cookie" is the smell people who survived report HCN to have. And it's not that space is full of a lethal-on-touch gas, that's the smell your nerves report when the sensory cells are dying faster than they can pass on a chemical signal.
I first read about this ages ago as a kid and was fascinated. I never figured it was probable though. Years later I'm finding it more and more likely in my completely worthless and undereducated opinion. It'd be crazy to eventually find out that many planets out there have similar DNA.
I read something by a SETI researcher that pointed out that some research focuses on finding DNA outside of earth (e.g. Mars) that has the reversed chirality of DNA on earth (i.e. corkscrews the opposite way of all life we've found on earth). This would be an incredibly strong indicator for life that actually came from somewhere else and wasn't just contaminated from DNA from earth that got on the equipment. They said "strong" instead of "certain" as it's still possible for a "shadow biome" on earth where the chirality is reversed that we just haven't found yet. This is important as there is no reason that it should be one way or the other (at least that scientists are currently aware of). As far as they can tell it should be 50:50, so chirality makes for an interesting indicator. Note: this is what I read over a decade ago. I'm no biologist.
There was that ISS experiment during multiple spacewalks that discovered marine microorganisms on the outer surface of the space station that got there somehow, many of them surviving the conditions. It's hard to explain by the contamination alone because some species were endemic to the places well outside the trajectory of the launchers.
The authors suggest/speculate about the existence of some ionospheric updraft or electromagnetic phenomenon capable of elevating them to the upper thermosphere where ISS is located. If that's true, panspermia hypothesis suddenly becomes much less far-fetched, and also the "reverse panspermia" you're talking about.
Well it was made out of plywood. Unless they made the wood poisonous to all life, it is also food. And humans basically exhale the rest of what fungi need to thrive.
Space is not all that inhospitable to life. There are strong theories that after major cataclysms on earth, rocks in space with life attached then reseeded earth when they came back down.
I was sorta hoping that radiation would mutate the Mir Fungus into something really catastrophic that would survive Mir's re-entry and then more or less destroy the world. Or at least that someone would have made a really nutso film based on such an idea.
Submission title is misleading (and not the article title). Fungi did not survive in space outside the ISS, but in a pressurized environment designed to be similar to the surface of Mars.
The equipment that has been sent to Mars has been sterilized in cleanroom conditions. Interplanetary contamination is something that space agencies take super seriously.
Fungi have metabolisms similar to those of animals. They eat dead biomass, breathe oxygen, and drink water. Mars is a dead planet with a CO2-rich atmosphere and no liquid water. Even if a spore got transported there, it would not be able to germinate.
: There is a chance that this dusty and dark ice might melt a few centimeters down. And any subsurface liquid water produced from melting will be protected from evaporating in Mars’ wispy atmosphere by the overlying blanket of ice.
Is it likely that Fungi would end up in the right places on Mars, and even then grow in these conditions? Probably not. But worth investigating given what is known of psychrophilic fungi.
: Fungi are able to grow and survive at low temperature and exist widely in polar and non-polar habitats. These cold regions are known for very low temperature, high ultra violet-B radiation, frequent freeze and thaw cycles and low water and nutrient availability.
Given what is known of fungi in general, there's no need to investigate it. Fungi and animals can't thrive in extremely low oxygen concentrations. Some species are especially hardy and are able to survive extreme conditions, but none are able to sustain their biological processes without oxygen.
I'm a bit perplexed about experiments like that. I get it why we did a lot of this in the early years of the Space Age to validate our assumptions about the hazards of outer space.
Then, there was some scientific curiosity about how certain life forms, such as complex plants or insects, might adopt to near-zero gravity. This was a bit harder to justify in practical terms, but interesting and hard to replicate by other means.
But what's the objective with this test? We can easily recreate similar conditions (pressure, temperature, illumination) here on Earth. So what have we learned to justify the cost? I'm not trolling, it's a sincere question.
Sure, but there's no reason to suspect that low gravity does anything interesting to fungi, of all things; and there's ample evidence that it doesn't from previous experiments, intentional and not. Other comments cite instances of the crews dealing with mold on the ISS.
Saprophytic means: it eats dead plants.
Necrotroph means: it kills a plant, and then eats the dead plant.
I have heard the term saprophytic many times, always related to fungi, but it's the first time i have heard the term necrotroph. My browser's spell correction underlines it with red like a word not spelled right. It is probably a new term.
In the context of these experiments the fungi don't really have to do anything in this Mars-like environment, except surviving. Many fungi can do that quite well by going in a dormant state.
If you want to take these results to extrapolate whether there could be living and "thriving" fungi on Mars right now: there are radiotrophic fungi that can extract energy from ionizing (and possibly non-ionizing) radiation. There could also be fungi capable of chemosynthesis, the production of sugar and amino acids using oxidation reactions as a fuel source.
The fungi used were lichenous and affixed to mars-like and moon-like substrata, not unlike the stone-like environments they were originally sourced from in Antarctica.
> Some fungi can survive the conditions of space, which is pretty incredible.
It is literally incredible, and the title is misleading.
The fungi was in some kind of box that was filled with a lot of CO2, a little O2 and H2O, and other stuff to simulate the atmosphere on Mars.
That box was then placed outside the space station.
It wouldn't survive if it was just growing in space, outside the space station. Believe me, I'm outside of it right now and it is not going to be fun[1].
1: I'm about to start doing my taxes-- blecch-- here on Earth, which is technically outside of the space station.
If even some hardy Earth organisms can survive (the article doesn't say anything about it, but this was almost certainly survival in a dormant desiccated state rather than being metabolically active doing fungus things) Martian conditions, it slightly raises the odds that whatever microbial life Mars may have once hosted may still exist in protected, hard-to-reach spots – possibly hundreds of meters beneath the surface like a surprising amount of Earth life.
It also slightly raises the odds that genetically modified fungi and lichen might be able to metabolize and grow on Mars at least if suitably protected, which may have implications on astronaut food and oxygen production as well as, much more speculatively, terraforming. Further, it has implications on planetary protection – the measures we take to avoid accidentally infesting other worlds with Earth life.
Our ants may have many questions too but we don't seem to understand whether they even have questions and we may not even know how to start engaging with them to answer them. Surely they don't seem to respond to our level of intelligence, so we should adapt to their level in order to tell them something they can understand. But if we achieve that, will the ants really perceive us as a higher level of intelligence? We would clearly stumble our way to approximate a communication channel the best possible way with them and use the feedback to learn how to get better at communicating, but that may take a lot of effort on our side because we may always assume we "bottomed out" their intelligence level and that's pointless to continue probing.
I now ask you to imagine an analogy with a species that is as smarter, bigger, more powerful and radically different from us as we are to ants.
Be careful what you hope for. For all we know, the answer might be, "Sorry, human, I'd love to chat, but I need to get your dish cleaned and racked up to dry before they close the lab for the eon. Now, how do you get the childproof cap off this bottle of antineutronium..."
Flagging an article doesn't do anything about the title, but kills virtually all further discussion if it's no longer on the front page -- which doesn't seem desirable.
didn't they do that to test the effects of being in space for a long time on general health, dna status? See how much bones degrade, if blood chemistry stays the same, etc.
Note that while the cultures were outside the Space Station, they were in containers simulating the conditions of Mars, so it doesn't seem like they were in the vacuum of Space itself, unless I've missed something in the article?
I think you're right: the atmosphere inside the container was artificial and intended to be equivalent to the atmosphere on Mars, with natural light from the Sun allowed to pass into the container through filters which also emulated the conditions on Mars.
If I'm not mistaken Mars' atmospheric is pressure is less than 1% of the Earth's atmospheric pressure. That is a lot closer to a vacuum than it is to Earth conditions.
What an interesting, but harrowing existence to be a part of. I don't expect humanity to last that long, but even if we did, then those would be quite the obstacles.
I did not know in 600 million years trees would basically go extinct. Even if it is an incredibly far away time, I wonder what the gradual process will be.
Indeed; one of the things I like best about the Ingenuity helicopter (sadly decommissioned only this week) is that it flew at a pressure that, were it on Earth rather than Mars, would be equivalent to twice as high as Concorde's cruising altitude!
“The most relevant outcome was that more than 60% of the cells of the endolithic communities studied remained intact after ‘exposure to Mars’, or rather, the stability of their cellular DNA was still high,” highlights Rosa de la Torre Noetzel from Spain’s National Institute of Aerospace Technology (INTA), co-researcher on the project.
It only takes a single success to propagate a species. Sustained with a food source, presumably you could select for a new species which can survive the radiation and near vacuum.
Why does we go through so much trouble to not let mars etc get polluted by life from earth, why don't we just send a bug chunk of hardcore life forms like this fungi and others on the red planet etc and go back later to see how they are fairing?
What are we trying to find or learn that life from earth will permanently remove the chance of?
For starters it becomes harder to find martian life. The earth life could kill the martian life before we get a chance to find it. Also, if the experiments detect signs of life, we won't be able to know if it's from martian life or from the earth life we brought along.
> What are we trying to find or learn that life from earth will permanently remove the chance of?
Species prove to be invasive all the time on earth when exposed to new ecosystems or environments, and usually that's at the expense of many potential discoveries about the life forms that are replaced.
Seeding the universe with life from our planet may make sense as a survival strategy, but there's no ceiling to the knowledge we can glean from life thats different from our own.
In short: we don't know what we don't know, and the gains from such knowledge could be endless.
So one of the things we are trying to learn is if there are other type of life forms than what we know from earth. What if do find something, there are no big size living things there but if did find some microbial Mars/X native life form, will we just let that be? Won't we still try to put ourselves there anyway? that's what we do on current planet being top of the food chain.
Yeah the whole safety dance is a bit of a farce. Everyone is willing to play along with the ethical considerations now because there's currently zero value to the Moon and Mars but if we had the technology and industrial capacity to start sending thousands of colonists, those rules would probably be discarded with much haste.
This is not about about some microbe conservation effort. The whole idea is to preserve the conditions in which life can be discovered, and if it is, studied. Think about how much harder it would be to detect Mars life if organic molecules from Earth are present in quantity, let alone the interaction that could occur.
Perhaps we are the only life in the universe. It would be a pity to have the earth destroyed and that is all gone, because we were so terrified of spreading life around.
> the gains from such knowledge could be endless.
Could be - but the gains from spreading Terran life around will be endless.
If life in the universe is actually really rare, isn’t it irresponsible for us to not be seeding life anywhere we can put it? If we put microbes on several planets and moons in the solar system those worlds could have complex and even intelligent lifeforms in millions of years.
> Approximately 1,300 colonies were picked from culture plates, identified, lypholipized, and stored for future reference. About 75% of all isolates were microorganisms considered indigenous to humans; the remaining isolates were associated with soil and dust in the environment.
So that if we do encounter that particular strain on Mars, we'll know its from Earth.
nitpick: fungi don't produce their own food; they need something to eat. what you need to get an ecosystem going is photosynthetic or chemotrophic organisms that produce their own food.
I don't know either. We could limit exposure to a tiny patch on the planet's surface and still have ample opportunity to look for signs of life on the rest of it.
I think that we want to exhaust any possibility that there was/is life in some form on mars without merging our biosphere with it just yet. I think to most of humanity that would be an extreme epiphany that you don't need a higher power or that humans are anything special outside of our own little mudball. Seems like a reasonable take for now. I'm sure if we actually do establish permanent colonies there it won't be a choice, although avoiding taking extremophiles that might easily adapt there is something we'll avoid for a while.
I am no biologist; I am unclear about the terms here.
Let say I have a piece of bread that has mold on it.
I leave it alone, the mold grows and consumes more of the bread.
The mold / fungi is "alive" in that it is growing and consuming.
Let us say that the fungi here was from moldy bread.
They shoot it into space, stuff it inside the lab and expose it to the
same environment.
Does survival then mean that it keeps eating more of the bread while
the experiment is taking place, so when they look at it afterwards
there is a lot more of it? But 40% of it has died?
Or does it mean that the cells making up the mold are entirely dormant
but is the DNA structure has remained intact for 60% of the mold and
the hypothesis is that if you brought it back to earth it would start
"being alive", growing, eating again?
>The most relevant outcome was that more than 60% of the cells of the endolithic communities studied remained intact after ‘exposure to Mars’, or rather, the stability of their cellular DNA was still high,”
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[ 335 ms ] story [ 4446 ms ] threadhttps://en.wikipedia.org/wiki/John_Titor
But what are the odds an asteroid hitting Earth has already seeded life elsewhere in the solar system?
Our universe would seem to them like the universe on the verge of heat death does to us. To my knowledge, I don't know of any fiction that explores this setting--it's on my bucket list to write.
[1] https://lweb.cfa.harvard.edu/~loeb/habitable.pdf
Can you point to any source for that? I've never heard of such a thing and can't find anything from a quick online search supporting that idea. Everything I read is that gravity will pull back any bacteria that get to the outer edges of the atmosphere, which makes sense because they'd need to have some force stronger than gravity to escape.
What information can you point to that supports the idea that we leave a "plume of life behind us"?
I think the idea behind an asteroid is that only something with that level of force could eject bacteria that could overcome the Earth's gravity to escape.
Edit: atmospheric escape [1] is a well-known phenomenon, but that's exclusively about gases, at the molecular level. It doesn't mention anything about bacteria, which are of course massive in comparison -- the factors that can cause a single atom or molecule to gain enough energy to escape gravity don't apply to things the size of bacteria.
[1] https://en.wikipedia.org/wiki/Atmospheric_escape
Relative to the center of the Earth (average gravity) , the atmosphere ends approximately at sea level.
Small particles aren't escaping based on their own velocity from random collisions. Maybe from interplanetary scraft like Voyager.
Impact erosion seems like it would have enough energy to eject microbes from the atmosphere given the amount of life in the troposphere [1].
[1] https://nautil.us/the-surprising-importance-of-stratospheric...
That's why helium escapes pretty fast. The other gas molecules still escape, but far far slower. The Maxwell Boltzmann distribution applies.
Something like a virus is far far heavier again, so the rate of escape would be miniscule. Not sure if it's small enough to have never happened across the surface of earth though.
https://sites.google.com/view/sources-big-bang-life/
https://youtu.be/JOiGEI9pQBs?si=kOHM_l0saPkEhWcX
I wonder to what extent the scientists who study these evolutionary clocks are able to factor in increasingly (or decreasingly) capable DNA replication and repair mechanisms. More faithful DNA replication and repair would artificially show a slower rate of genome evolution.
https://www.nature.com/articles/s41586-023-06600-9
Of course that likely doesn’t apply to life as we know it, assuming our estimates of the age of the sun and the universe are correct.
It is hard to imagine life without a large variety of atoms.
Stars with rocky planets during the habitable epoch "lie ∼8.5 standard deviations (σ) away on the exponential tail of the Gaussian probability distribution of initial density perturbations," though "their abundance could have been significantly enhanced by primordial non-Gaussianity."
[1] https://arxiv.org/pdf/1312.0613.pdf
It sounds like there is a chance some atomic fusion could have occurred at this time, but It would be isolated to a few instances in our light cone. This is a pretty different than the entire universe awash in favorable conditions to life.
Then again, he also wrote a lot about the self-transforming machine elves he met while stoned out of his gourd on DMT.
The Stoned ape theory "has largely been rejected by the scientific community, who cite numerous alleged discrepancies within his theory and claim that his conclusions were arrived at via a fundamental misunderstanding of Fischer's studies" on "psychedelic drugs, schizophrenia, the perception-hallucination continuum model of altered states of consciousness, and...gustation" [1][2].
[1] https://en.wikipedia.org/wiki/Stoned_ape_theory
[2] https://en.wikipedia.org/wiki/Roland_L._Fischer
I read something by a SETI researcher that pointed out that some research focuses on finding DNA outside of earth (e.g. Mars) that has the reversed chirality of DNA on earth (i.e. corkscrews the opposite way of all life we've found on earth). This would be an incredibly strong indicator for life that actually came from somewhere else and wasn't just contaminated from DNA from earth that got on the equipment. They said "strong" instead of "certain" as it's still possible for a "shadow biome" on earth where the chirality is reversed that we just haven't found yet. This is important as there is no reason that it should be one way or the other (at least that scientists are currently aware of). As far as they can tell it should be 50:50, so chirality makes for an interesting indicator. Note: this is what I read over a decade ago. I'm no biologist.
The authors suggest/speculate about the existence of some ionospheric updraft or electromagnetic phenomenon capable of elevating them to the upper thermosphere where ISS is located. If that's true, panspermia hypothesis suddenly becomes much less far-fetched, and also the "reverse panspermia" you're talking about.
https://www.hindawi.com/journals/tswj/2018/7360147/ - one of the papers related to the experiment
https://nplus1.ru/material/2020/02/21/iss-test-experiment - a pop-sci article and an interview with a PI of that experiment (in Russian, use a translator)
https://newspaceeconomy.ca/2023/03/29/mold-in-space-the-hidd... has a picture of a wall panel covered in the stuff after astronauts hung damp workout clothes out to dry.
https://www.permaculturenews.org/2017/03/27/aggressive-fungu...
Thank you for the correction.
Space is not all that inhospitable to life. There are strong theories that after major cataclysms on earth, rocks in space with life attached then reseeded earth when they came back down.
: In 2018, Mars Express located a large lake of liquid water under the Martian polar ice.
https://web.archive.org/web/20210902121223/https://earthsky....
: There is a chance that this dusty and dark ice might melt a few centimeters down. And any subsurface liquid water produced from melting will be protected from evaporating in Mars’ wispy atmosphere by the overlying blanket of ice.
Is it likely that Fungi would end up in the right places on Mars, and even then grow in these conditions? Probably not. But worth investigating given what is known of psychrophilic fungi.
https://link.springer.com/article/10.1007/s11157-016-9395-9
: Fungi are able to grow and survive at low temperature and exist widely in polar and non-polar habitats. These cold regions are known for very low temperature, high ultra violet-B radiation, frequent freeze and thaw cycles and low water and nutrient availability.
The main user of oxygen is the mitochondria, and even some non-anaerobic fungi can survive fine after losing their mitochondria.
Then, there was some scientific curiosity about how certain life forms, such as complex plants or insects, might adopt to near-zero gravity. This was a bit harder to justify in practical terms, but interesting and hard to replicate by other means.
But what's the objective with this test? We can easily recreate similar conditions (pressure, temperature, illumination) here on Earth. So what have we learned to justify the cost? I'm not trolling, it's a sincere question.
Saprophytic means: it eats dead plants. Necrotroph means: it kills a plant, and then eats the dead plant.
I have heard the term saprophytic many times, always related to fungi, but it's the first time i have heard the term necrotroph. My browser's spell correction underlines it with red like a word not spelled right. It is probably a new term.
If you want to take these results to extrapolate whether there could be living and "thriving" fungi on Mars right now: there are radiotrophic fungi that can extract energy from ionizing (and possibly non-ionizing) radiation. There could also be fungi capable of chemosynthesis, the production of sugar and amino acids using oxidation reactions as a fuel source.
It is literally incredible, and the title is misleading.
The fungi was in some kind of box that was filled with a lot of CO2, a little O2 and H2O, and other stuff to simulate the atmosphere on Mars.
That box was then placed outside the space station.
It wouldn't survive if it was just growing in space, outside the space station. Believe me, I'm outside of it right now and it is not going to be fun[1].
1: I'm about to start doing my taxes-- blecch-- here on Earth, which is technically outside of the space station.
It also slightly raises the odds that genetically modified fungi and lichen might be able to metabolize and grow on Mars at least if suitably protected, which may have implications on astronaut food and oxygen production as well as, much more speculatively, terraforming. Further, it has implications on planetary protection – the measures we take to avoid accidentally infesting other worlds with Earth life.
Why else would people for example keep ant colonies in their home or grow kits?
Hopefully we are not alone and they come back soon. I have many questions.
I now ask you to imagine an analogy with a species that is as smarter, bigger, more powerful and radically different from us as we are to ants.
Submitters: "Please use the original title, unless it is misleading or linkbait; don't editorialize." - https://news.ycombinator.com/newsguidelines.html
Flagging an article doesn't do anything about the title, but kills virtually all further discussion if it's no longer on the front page -- which doesn't seem desirable.
0.0060 atm (0.6%), to be exact [1].
[1] https://en.wikipedia.org/wiki/Atmosphere_of_Mars
https://en.wikipedia.org/wiki/Atmospheric_escape
https://en.wikipedia.org/wiki/Future_of_Earth
What an interesting, but harrowing existence to be a part of. I don't expect humanity to last that long, but even if we did, then those would be quite the obstacles.
Life itself started about 3.5 bn years ago. So we’re well beyond the half-time of life on this planet.
“The most relevant outcome was that more than 60% of the cells of the endolithic communities studied remained intact after ‘exposure to Mars’, or rather, the stability of their cellular DNA was still high,” highlights Rosa de la Torre Noetzel from Spain’s National Institute of Aerospace Technology (INTA), co-researcher on the project.
What are we trying to find or learn that life from earth will permanently remove the chance of?
Species prove to be invasive all the time on earth when exposed to new ecosystems or environments, and usually that's at the expense of many potential discoveries about the life forms that are replaced.
Seeding the universe with life from our planet may make sense as a survival strategy, but there's no ceiling to the knowledge we can glean from life thats different from our own.
In short: we don't know what we don't know, and the gains from such knowledge could be endless.
Why should we? Microbes are not sentient.
> the gains from such knowledge could be endless.
Could be - but the gains from spreading Terran life around will be endless.
Besides, Mars is a lifeless hulk.
From there, https://journals.asm.org/doi/10.1128/aem.33.2.379-384.1977 is "Microbiological profiles of the Viking spacecraft"
Note things like:
> Approximately 1,300 colonies were picked from culture plates, identified, lypholipized, and stored for future reference. About 75% of all isolates were microorganisms considered indigenous to humans; the remaining isolates were associated with soil and dust in the environment.
So that if we do encounter that particular strain on Mars, we'll know its from Earth.
---
One that's on the interesting side and has more than just an available abstract: Europa Clipper planetary protection probabilistic risk assessment summary https://www.sciencedirect.com/science/article/abs/pii/S00320...
The paper, from 2015: https://doi.org/10.1089%2Fast.2015.1324
Let say I have a piece of bread that has mold on it. I leave it alone, the mold grows and consumes more of the bread. The mold / fungi is "alive" in that it is growing and consuming.
Let us say that the fungi here was from moldy bread. They shoot it into space, stuff it inside the lab and expose it to the same environment.
Does survival then mean that it keeps eating more of the bread while the experiment is taking place, so when they look at it afterwards there is a lot more of it? But 40% of it has died?
Or does it mean that the cells making up the mold are entirely dormant but is the DNA structure has remained intact for 60% of the mold and the hypothesis is that if you brought it back to earth it would start "being alive", growing, eating again?
>The most relevant outcome was that more than 60% of the cells of the endolithic communities studied remained intact after ‘exposure to Mars’, or rather, the stability of their cellular DNA was still high,”
If they were spores, they would test to see if the spores were viable.
If it was the mycelium body they would see if it was still viable to grow.