NASA decided Saturday it wasn’t worth the risk to let astronauts try to pry open a jammed space shuttle hatch, and canceled all spacewalks for Columbia’s mission.
Mission Control was concerned that astronauts Tamara Jernigan and Thomas Jones might not have been able to close it with a tight seal after their spacewalk if they forced it open.
Without a decent seal, the chamber between the crew cabin and the open cargo bay could not be repressurized, and the spacewalkers would be stuck outside the cabin with a dwindling supply of oxygen.
Two spacewalks had been planned for Columbia’s 16-day flight to test tools and techniques for building an international space station.
NASA decided to focus instead on how to open and close the hatch in the unlikely event an emergency spacewalk is needed to close the cargo-bay doors before returning to Earth. The chance of that happening is extremely low; such an emergency spacewalk has never been required in 15 years of shuttle flight.
Jernigan and Jones were ready to use two crowbarlike tools if asked to go out Saturday night. Flight controllers went down to the wire in making their decision just before the astronauts woke up Saturday afternoon.
Jerry Ross, an astronaut skilled in spacewalking who worked on the problem from Mission Control, empathized with Jernigan and Jones.
“This was going to be the first opportunity for both of them to go out the hatch,” Ross said. “It’s also frustrating for us because we like to think that we can always solve problems and this time we’ve struck out.”
Engineers are perplexed as to why the handle on the hatch would not swing into the unlock position. On Friday, they suspected the door might be slightly out of alignment and that the astronauts might be able to shove it back in place. But that situation could not be duplicated with equipment on the ground.
Their latest best guess: some sort of jam in the gear mechanism to which the handle is attached. That would be unfixable in orbit.
NASA opted against brute force so engineers could inspect the jammed hatch, as is, after the flight.