Nov 22, 2025 06:05 AM
(This post was last modified: Nov 22, 2025 06:20 AM by Yazata.)
I like this. It's consistent with my speculations about panspermia, about the possibility that life didn't originate here on Earth at all but rather arrived here from... somewhere else.
My reason for speculating like that is that life seems to have appeared on Earth very early, only a few hundred million years after the Earth congealed from collisions of planetesmals, and perhaps not that long after a Mars-sized body struck the Earth and created the Moon. That collision would have rendered the entire Earth's surface molten and unsuitable for life.
When I contemplate even the simplest prokaryotes, they turn out to be incredibly complex little wonders of nanotechnology on an atomic scale. So however life originated, which is currently unknown, I expect that it probably took a long time, an extended period of pre-biotic evolution of chemical replicators.
So how do we square that circle? How do we make the very early appearance of life on Earth consistent with an extended period of chemical evolution of pre-biotic replicators, a period in which the basic cellular architecture, genetic code and cellular metabolism were hammered out?
https://astrobiology.com/2025/11/this-mo...space.html
"Fujita’s team subjected Physcomitrium patens, a well-studied moss commonly known as spreading earthmoss, to a simulated a space environment, including high levels of UV radiation, extreme high and low temperatures, and vacuum conditions.
They tested three different structures from the moss—protenemata, or juvenile moss; brood cells, or specialized stem cells that emerge under stress conditions; and sporophytes, or encapsulated spores—to find out which had the best chance of surviving in space...
The researchers found that UV radiation was the toughest element to survive, and the sporophytes were by far the most resilient of the three moss parts. None of the juvenile moss survived high UV levels or extreme temperatures. The brood cells had a higher rate of survival, but the encased spores exhibited ~1,000x more tolerance to UV radiation. The spores were also able to survive and germinate after being exposed to −196°C for over a week, as well as after living in 55°C heat for a month.
The team suggested that the structure surrounding the spore serves as a protective barrier, absorbing UV radiation and blanketing the inner spore both physically and chemically to prevent damage. The researchers note that this is likely an evolutionary adaptation that allowed bryophytes—the group of plants to which mosses belong—to transition from aquatic to terrestrial plants 500 million years ago and survive several mass extinction events since then.
To see if this adaptation could make the sporophytes fit for the actual conditions of space, the team sent the spores beyond the stratosphere.
In March 2022, the researchers sent hundreds of sporophytes to the ISS aboard the Cygnus NG-17 spacecraft. Once they arrived, the astronauts attached the sporophyte samples to the outside of the ISS, where they were exposed to space for a total of 283 days. The moss then hitched a ride back to Earth on SpaceX CRS-16 in January 2023 and was returned to the lab for testing.
“We expected almost zero survival, but the result was the opposite: most of the spores survived,” says Fujita. “We were genuinely astonished by the extraordinary durability of these tiny plant cells.”
Over 80% of the spores survived their intergalactic journey, and all but 11% of the remaining spores were able to germinate back in the lab. The team also tested the chlorophyll levels of the spores and found normal levels for all types, with the exception of a 20% reduction in chlorphyll a—a compound which is particularly sensitive to changes in visual light, but this change didn’t seem to impact the health of the spores...
Curious how much longer the spores could have survived in space, Fujita’s team used the data from before and after the moss’s expedition to create a mathematical model. They predicted that the encased spores could have survived for up to 5,600 days—approximately 15 years—under space conditions. However, they emphasize that this number is just a rough estimate...
My reason for speculating like that is that life seems to have appeared on Earth very early, only a few hundred million years after the Earth congealed from collisions of planetesmals, and perhaps not that long after a Mars-sized body struck the Earth and created the Moon. That collision would have rendered the entire Earth's surface molten and unsuitable for life.
When I contemplate even the simplest prokaryotes, they turn out to be incredibly complex little wonders of nanotechnology on an atomic scale. So however life originated, which is currently unknown, I expect that it probably took a long time, an extended period of pre-biotic evolution of chemical replicators.
So how do we square that circle? How do we make the very early appearance of life on Earth consistent with an extended period of chemical evolution of pre-biotic replicators, a period in which the basic cellular architecture, genetic code and cellular metabolism were hammered out?
https://astrobiology.com/2025/11/this-mo...space.html
"Fujita’s team subjected Physcomitrium patens, a well-studied moss commonly known as spreading earthmoss, to a simulated a space environment, including high levels of UV radiation, extreme high and low temperatures, and vacuum conditions.
They tested three different structures from the moss—protenemata, or juvenile moss; brood cells, or specialized stem cells that emerge under stress conditions; and sporophytes, or encapsulated spores—to find out which had the best chance of surviving in space...
The researchers found that UV radiation was the toughest element to survive, and the sporophytes were by far the most resilient of the three moss parts. None of the juvenile moss survived high UV levels or extreme temperatures. The brood cells had a higher rate of survival, but the encased spores exhibited ~1,000x more tolerance to UV radiation. The spores were also able to survive and germinate after being exposed to −196°C for over a week, as well as after living in 55°C heat for a month.
The team suggested that the structure surrounding the spore serves as a protective barrier, absorbing UV radiation and blanketing the inner spore both physically and chemically to prevent damage. The researchers note that this is likely an evolutionary adaptation that allowed bryophytes—the group of plants to which mosses belong—to transition from aquatic to terrestrial plants 500 million years ago and survive several mass extinction events since then.
To see if this adaptation could make the sporophytes fit for the actual conditions of space, the team sent the spores beyond the stratosphere.
In March 2022, the researchers sent hundreds of sporophytes to the ISS aboard the Cygnus NG-17 spacecraft. Once they arrived, the astronauts attached the sporophyte samples to the outside of the ISS, where they were exposed to space for a total of 283 days. The moss then hitched a ride back to Earth on SpaceX CRS-16 in January 2023 and was returned to the lab for testing.
“We expected almost zero survival, but the result was the opposite: most of the spores survived,” says Fujita. “We were genuinely astonished by the extraordinary durability of these tiny plant cells.”
Over 80% of the spores survived their intergalactic journey, and all but 11% of the remaining spores were able to germinate back in the lab. The team also tested the chlorophyll levels of the spores and found normal levels for all types, with the exception of a 20% reduction in chlorphyll a—a compound which is particularly sensitive to changes in visual light, but this change didn’t seem to impact the health of the spores...
Curious how much longer the spores could have survived in space, Fujita’s team used the data from before and after the moss’s expedition to create a mathematical model. They predicted that the encased spores could have survived for up to 5,600 days—approximately 15 years—under space conditions. However, they emphasize that this number is just a rough estimate...
