The Columbia is physically incapable of docking at the space station. The Columbia is too heavy. Second, the Columbia was at a lower orbit and didnt have enough fuel to take it up to the higher level and catch the ISS (this isnt Star Trek). Third, the escape pod on the ISS only carries three and one of those would have to be the Russian on board the station who can pilot it. Astronauts who have been on board the ISS have quipped it would have to be one hell of an emergency for them to risk return using the escape pod. They dont trust it.
Look ... I'm just asking these questions because I don't know what, if anything, NASA could've done. I'm just being curious. I'm not making any Star Trek or Bruce Willis style suggestions here. I'm merely looking for information. I appreciate the straight forward factual answers, but there's no reason for the smart-a$$ Star Trek or Bruce Willis jabs.