During a 10-hour-long inspection of Space Shuttle Atlantis’s heat shield on Tuesday, astronauts found a trail of damage on its starboard wing. This was caused by launch debris that fell from the shuttle’s external tank during liftoff. NASA says that the dings are minor but is taking no chances, and it will investigate the damaged wing further.

Ever since the 2003 Columbia disaster, when damage to the shuttle’s wing went undetected and the shuttle broke apart during reentry, killing seven astronauts, NASA has developed new technology to better inspect the shuttle, and has equipped astronauts with the necessary tools should a repair need to be conducted. In the worst case, if the shuttle is damaged beyond repair, NASA has a second shuttle, Endeavour, on the launch pad ready to depart on a rescue mission.

New policies put in place after the Columbia disaster require astronauts to inspect the shuttle twice: once after liftoff, and once again before descent. Atlantis astronauts spotted the damage during their routine post-liftoff check, in which they scan the heat shield using a pole mounted with a camera and laser sensors. Sensors on the shuttle’s wings also recorded an impact 106 seconds after liftoff, and cameras on the external fuel tank showed debris falling at the same time.

The images from the astronauts’ inspection were then beamed to Earth, where they were analyzed by a team of image experts. “This is not something that we’re very concerned about, but we want the team to do our normal assessment and evaluation of it. And we will do that overnight tonight,” LeRoy Cain, deputy shuttle-program manager at NASA, said during a press briefing yesterday.

The dings could compromise the shuttle’s thermal protection system, which is a combination of reinforced carbon-carbon (RCC) on the wing leading edge, thermal blankets on the fuselage, and thermal protective tiles covering the underside of the vehicle and the nose cap. This system protects the spacecraft and its human occupants from the extreme heat of reentry into Earth’s atmosphere.

Space Shuttle Atlantis lifted off from Cape Canaveral, FL, on May 11 for a final servicing mission to the Hubble Space Telescope.