The Troubled Flight of STS-27

The disastrous 2003 flight of the Space Shuttle Columbia is well known and eventually led to the demise of the Shuttle program. I knew that other missions had suffered tile damage from debris falling off the solid rocket boosters or external tank, but I had not heard of what happened to STS-27. That's not surprising, because it was a secret military mission. 

AmericaSpace published an article about it in 2018, which I somehow missed hearing about it. In a nutshell, debris came off one of the SRBs and struck the underside of the orbiter. The astronauts saw the damage during the mission and we're convinced they would not survive re-entry. It's a sobering and scary story. 

Early the next day, 3 December 1988, the crew awoke to worrying news. A review of launch video showed a piece of debris—probably a bit of ablative insulator—breaking away from the nose of one of the Solid Rocket Boosters (SRBs) around 85 seconds after liftoff and hitting Atlantis’ fragile Thermal Protection System (TPS). If the heat shield was damaged, it could spell disaster during the fiery return to Earth and Gibson’s was instructed to use RMS cameras to acquire imagery. With mounting horror, the camera revealed white streaks of damage along the shuttle’s fuselage, evidence that the outer black coating had been stripped away by a kinetic impact. “We could see that at least one tile had been completely blasted from the fuselage,” Mullane wrote. “The white streaking grew thicker and faded aft beyond the view of the camera. It appeared that hundreds of tiles had been damaged and the scars extended outboard toward the carbon composite panels on the leading edge of the wing.”

Gibson reported the extent of the damage to flight controllers, but the response came back that the images did not look to represent a significant breach of the TPS. Worse, the astronauts’ downlinked data was encrypted for security and its slowness meant that the images received on the ground were of low quality. Flight controllers were convinced from the grainy images that the damage was not severe and that the crew were mistakenly seeing damage in conditions of poor lighting. For his part, Gibson was furious and certain that Atlantis had sustained severe damage. He told his crew to enjoy the final days of the flight. “No use dying all tensed-up,” he said.

There's a picture of the damage to the orbiter's underside in this Wikipedia article. They were very lucky to make it back in one piece.