Or you can look at it as a hallucination as she ran out of oxygen, and she's really floating dead in space.
Even if you look on it as an hallucination I think they missed out on a proper ending.
I am with @TomGeorge's sentiment for most films. There are Sci-Fi fils where the whole plot really annoys me because it is just stupid e.g. drilling to the centre of the Earth to restart the rotation of the core with nuclear weapons. There are other films that are basically quite good and factual and then they throw in one really stupid error that just destroys the illusion. I suppose it is the uncanny valley thing but for films instead of robots. If the film is clearly escapist like "Lost in Space" all is well, but if it attempts realism small imperfections grate.
Recently I saw "Hardcore Henry". If you can stomach the opening titles then you are probably the kind of sick individual that will watch the whole violent gorefest to the end. Not one of my favorite films but it was interesting because the entire film was seen through the eyes of Henry. I don't think I have ever seen a film shot like that before and the shoot-em-up action did carry me along.
The unusual filming made me remember "Run Lola Run". Now that was a good film and it was filmed in an unusual way which they managed to pull off. I will not spoil things by saying what they did, I was expecting to be dissapointed but it really worked.
For dog lovers "Benji" is a good family film (watch the end credits as well). The family pooch is going to have to pull its socks up and learn a few tricks after that one though.