Engineers with the U.S. space agency say an object that floated away from the space shuttle Friday is a metal clip and that it will not affect the shuttle's landing Saturday.

Astronauts aboard the space shuttle Discovery spotted the rectangular object, about 30 to 45 centimeters long, during routine tests of the spacecraft's control systems and steering jets. NASA reports the crew also saw a bump or protrusion on the shuttle's rudder.

Experts say the bump on the steering vane could be a piece of the shuttle's heat insulation. However, NASA officials say that area at the rear of the spacecraft is not subject to extremely high temperatures.

Discovery is scheduled to return to Earth at about 15:15 Universal Time (11:15 a.m. EDT), on Saturday, after a mission in which the astronauts successfully attached a new Japanese laboratory to the International Space Station. The seven-member crew includes a Japanese astronaut.

The shuttle pulled away from the space station on Wednesday. Its crew used a laser-tipped boom to inspect the craft's wings and nose before returning home.

Some information for this report was provided by AFP and AP.