A lot of theories after the airing of 'The Impossible Astronaut' that the Astronaut is River Song and we have witnessed her kill "the best man she has ever known", The Doctor.
The theory also goes that this is the event which leads to her arrest and imprisonment in the Stormcage.
Good theory. I tend to believe it myself.
One logic issue that Moffat will have to deal with. If that is River Song in the Astronaut suit, she killed The Doctor in 2011. She is in prison in the 51st Century.
How is it that the 51st century would hold River responsible for a crime committed in 2011?