Was an Armageddon-style rescue possible at all

• NASA did not attempt to examine Columbia’s left wing with high-powered telescopes on the ground, 290 km below, or with spy satellites

• NASA did not ask the crew of International Space Station to use its cameras to examine the wing when the two ships passed within a few hundred miles of each other several times over the past two weeks

• NASA did not consider a spacewalk by the crew to inspect the left wing. Two of Columbia’s astronauts, Michael Anderson and David Brown, were trained to do a spacewalks. But neither was trained to do anything more than simple repair. A spacewalk to reach the underside of the wings could have been suicidal, as there is nothing to hold on to, and the astronauts did not have mini-jetpacks to propell themselves. The astronauts could have floated off and never come back to the shuttle.

• Could NASA have sent another shuttle to the rescue? In theory, yes. Normally it takes four months to prepare a shuttle for launch. But in a crisis, shuttle managers say they might be able to put together a launch in less than a week if a shuttle were already on the pad. Columbia had enough fuel and supplies to remain in orbit until Wednesday. With shuttle Atlantis ready to be moved to its pad, it theoretically could have been rushed into service.

• Could Columbia’s astronauts have abandoned ship and climbed aboard the International Space Station? Because Columbia was in an entirely different orbit, it did not have enough fuel to fly to the ISS. Even if the shuttle could have limped there, it could not have docked as it was not equipped with a docking ring.

• NASA could have had the shuttle descend through the atmosphere at a much shallower angle of entry in hopes of relieving the heat on the ship. But that could have had the shuttle coming in too fast to make a safe landing.