so we needed to do the surgery while mark was up in space. >> she was literally going to be in the operating room while we were docking with the international space station. >> loud and clear, good morning. >> the whole thing was a big exercise in compartmentalization. that whole procedure on the day you're going to dock lasts for hours. so, i just have to, at least for this period of time, forget about the surgery. >> we had a special type of ct scan that gives information about the shape of gabby's skull. and then the prosthetic is made to fit it perfectly. >> i am manually trying to fly these two vehicles within 2 inches of each other. and they're both going 17,500 miles an hour. >> we have a large part of the skull exposed. you see the curvature. >> if you're not focused, if you skip something, if you screw something up, the problems you can induce are not easily