I might be a little fuzzy on the details near the end there, but I'm pretty sure I got the gist of it.
I really enjoyed the film, but it got silly at the end. A+ for the first half. C- for the second half. Overall, I went with a B+.
That wraps up my impression. The second part / space station seemed essentially like a repetition of the ISS part (to arrive at the 90 minute screen time?), except that a fire extinguisher WALL-E-style was used as thruster (problem: unless you use your wrist mirror you are unable to see where the thrust propels you to...).
I really enjoyed the film for many of its visuals, sound design and this continuous shot in the beginning (really conveying to us the experience of being there) and will purchase the 3D Blu-ray but some of the scientific nonsense really spoiled part of the experience and this great interview with an actual NASA astronaut
revealed some of it.
Interestingly the space shuttle started to revolve around its own axis and - had the shuttle's arm still been attached - an astronaut at the end of the arm would have experienced centrifugal forces that would have pushed him or her away from the shuttle.
That's the kind of centrifugal push the filmmaker would have needed to justify the ISS scene (whatever would have made the ISS rotate around its own axis is unimportant, but it would have provided the scientific explanation for this pivotal scene...).
At that moment I gave up all hope to watch a film that had seemed thus far to hold on to "Science Fact", relaxed and enjoyed the breath taking (...) rollercoaster ride in Earth's orbit.
IMHO it's just sad that the film could have used more "science" and still have the same kind or drama or even more:
Former NASA astronaut Scott Parazynski said that a tiny fragment flying with bullet speed would probably ignite the oxygen supply of an EVA suit upon impact penetration. So we could have had an exploding astronaut plus
the gruesome image of a space shuttle pilot's head with a hole through which to see Earth.
Again, a very good film but compared to the depiction of spacecraft and zero gravity in MISSION TO MARS there's more fiction than fact in it.