Why is this surprising? Oxygen is the 3rd most abundant element in the universe, behind hydrogen & helium.
They didn’t expect to find molecular oxygen on a comet. They must now revise their previous attitudes of how Earth came to have its oxygen, since they have said for decades that our water came from comets, apparently or oxygen did as well......................
Oxygen is the second most corrosive element in the Universe, only fluorine is more active.
Oxygen only exists as a free element in the earth’s atmosphere because of the constant replenishment through photosynthesis. There may be other forms of photosynthesis elsewhere, but the practicality of uncombined oxygen, in the absence of frequent replenishment, is highly unlikely.
Wow, a comet towing a spacecraft, wonder who hooked it up.