Double ridge formation over shallow water sills on Jupiter’s moon Europa

Then again, there's plenty of theories that asteroids and other impacts have caused enough of a splash to throw trace life bearing materials into space and eventually onto other planets or moons.

My current theory is that we will find traces of e.g. bacteria all over our solar system, but it'll be genetically traceable back to Earth. That said, if it turns out life as we know actually started on e.g. Mars, that would be huge and probably a big accelerator for more missions there.

And obviously absence of anything toxic. In short lot of things need to align.

Now, even if there are conditions favorable for our bacteria, the question of competition remains. Hypothetically, the invaders can carve niche in local ecology, as they often do on Earth, or they might utterly fail, as happens even more often on Earth.

If there are organisms on Europa already, and that is a big 'if', they would have several billions of years worth of head start adapting to the environment and molding it to their image. Conversely, newly introduced bacteria, already damaged by exposure to deep space and deprived of nutrients for many months or years, would see it for the first time.

It isn't given that this experience would work out for them, to say at least.

https://sma.nasa.gov/sma-disciplines/planetary-protection

https://www.esa.int/Science_Exploration/Human_and_Robotic_Ex...

There's a handbook and everything:

https://ec.europa.eu/research/participants/documents/downloa...

Is that a typo or a comment on the current political situation?

Anyway, a couple of meters of water would block all radiation, and the energy source would be tidal forces from Jupyter, not the Sun (which is what would also keep the core warm enough for liquid water. Also why Io has intense volcanic activity).

I visited once, and the residents were friendly. Europe is quite nice.

I think many scientists would agree: If there is life on any world in the Solar System, we should not land there.

[1]: https://nap.nationalacademies.org/read/26522/chapter/2

Fragile nucleic acids may not be the heritable information storage mechanism of extraterrestrial life.

I share your cynicism, though.

I'll continue to believe that this is bioluminescence.

How well does water shield radiation like this? For much of it (electrons, UV photons) a thin film on the surface could be enough protection. A layer of salty ice should be more than sufficient, I would think.

Both Europa and Titan are technically ocean worlds, but the likelihood of Titan containing life is much lower I think, given it is so cold that methane is the main surface liquid.

"Biologists have known since the 1930s the lake is "not dead yet". Instead, it's full of microbes that get along quite happily in the salty soup, for it keeps out competitors that would take over in a more hospital aqueous environment. In general, the water contains 1,000 to 10,000 archaea* per ml, a much lower concentration of life than in seawater, but quite respectable, all in all, for a place where one molecule in three is not water. Occasionally, when conditions are right, the sea blooms red with life. This happened in 1980 and 1992."

from: https://blogs.scientificamerican.com/artful-amoeba/fountains...