Seems it's my review that you disagree with entirely, as I was also the one who mentioned it beggaring belief!
Whether it was a feeling or not, it's completely ludicrous that she would have a feeling that there was a colony in such a specific location, and then it turned out to be the case. The whole film was science-based, and this was just ... crap. It's Hollywood's obsession of ending everything in a neat little package that leaRAB to ridiculous, unbelievable endings like this.
I understand what you say about depressing endings - I remember coming out of The Pledge and being utterly depressed, though thinking it was a great film - but I think this film deserved something more profound than the ending it was given.