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.
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!
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.
