Agency Doesn't Know What Caused Damage To Radiator Panel

Did the space shuttle Atlantis take a ding during its recent mission to the International Space Station? Experts outside of NASA reported Wednesday they thought so... and late Thursday afteroon, NASA confirmed reports the agency is studying a dent, one-tenth of an inch deep, it refers to as Ding 18.

The crater was found in one of the shuttle's two thermal radiators. The radiators fold out of the cargo bay to shed excess heat from the cabin. They aren't exposed during launch and reentry... so the damage occurred while the shuttle was in orbit.

Internal NASA documents refer to the ding as the first or second largest hit in the shuttle's history. The document also notes that had whatever dinged the thermal panel hit an RCC -- or reinforced carbon-carbon panel, which make up the shuttle's outer skin -- it would've made more than a dent; it might even have made a hole.

It was a hole in the shuttle Columbia's leading edge RCC that led to its breakup on reentry in 2003. NASA has determined that damage likely came as foam shedding off the fuel tank during launch impacted the panel.

"The nature of the object that hit the shuttle radiator isn’t known," NASA acknowledged on its website.

A micrometeoroid, or a small piece of floating debris, are seen as possible culprits.

Scientists also don't know if the damage is related to the small pieces of debris shuttle astronauts saw around the orbiter towards the end of the mission.

Atlantis was never in any danger on its recent mission. An on-orbit shuttle inspection program NASA instituted after the Columbia tragedy would likely have found any damage to critical components.

Had the thermal radiator been destroyed, NASA would have just cut the mission short -- de-orbiting the shuttle within 24 hours after the radiator's failure.

FMI: www.nasa.gov/shuttle