Yes, it can be...but water molecules are not oxygen molecules (basic chemistry here), and I've not heard that we found "oxygen" on Europa. Doesn't mean we haven't, I just haven't kept up with the discoveries.

Still, oxygen implies we are talking about atmospheres here...and it is ridiculous to consider that Europa could have an oxygen-atmosphere capable of supporting life.

I think it is very confusing astronomy to infer that oxygen would make life possible on Europa when, in fact, it would be the presence of water and organic compounds. Gaseous oxygen was poisonous to early life on Earth...and is still considered useless (a waste product) by most plant life. But I didn't get the impression that Endor was thinking of alleged Europan oxygen as being a waste product from existing life.

Eric