'Why do you think it is...', I asked Dr. Cook ... 'that brain surgery, above all else—even rocket science—gets singled out as the most challenging of human feats, the one demanding the utmost of human intelligence?'
[Dr. Cook answered,] 'No margin for error.'

We've all seen Apollo 13. NASA guys always have the old 'plastic bag, cardboard tubing, and duct tape' option to fall back on when the shit hits the fan. Neurosurgeons have no such leeway. What it comes down to is this: if a brain surgeon screws up, it means a multi-million-dollar malpractice suit, but if a rocket scientist screws up, it means a multi-million-dollar hit movie starring Tom Hanks.