The Atlantis astronauts uncovered a 21-inch stretch of nicks on their space shuttle Tuesday, but NASA said the damage did not appear to be serious. The damage was likely the result of debris that came off the fuel tank shortly after liftoff Monday. The astronauts were inspecting their ship while racing to the Hubble Space Telescope when they came across the nicks spread over four to five thermal tiles.

A NASA photo shows what appears to be about 10 white scuff marks, officials hadn't counted how many yet that are around the edge of the shuttle where the right wing joins the fuselage and the belly curves up to the top of Atlantis.

"It doesn't look very serious," Mission Control said. "Those tiles are pretty thick. The nicks look to be pretty small." And a decision late Tuesday by NASA managers indicated that the problem was minor and wouldn't require much more examination.

This repair mission is especially risky, a rescue shuttle is on standby for the first time ever because of the debris-littered orbit of Hubble. Unlike other space flights, the astronauts can't reach the International Space Station because it is in a different orbit than the telescope.

NASA managers weren't too worried Tuesday, saying this type of damage looks similar to nicks seen in the past five or six missions that were safe. "The area is not as critical" as other parts on the shuttle wing, deputy shuttle program manager LeRoy Cain said in a Tuesday afternoon news conference. "The damage itself appears to be relatively shallow and it's not a very large area of damage."

This image provided by NASA on Tuesday May 12, 2009 and annotated by source, shows white scuff marks around the edge of the shuttle where the right wing joins the fuselage and the belly curves up to the top of Atlantis. The Atlantis astronauts uncovered a 21-inch stretch of nicks on their space shuttle Tuesday, but NASA said the damage did not appear to be serious. (AP Photo/NASA)