Washington, July 10 (Xinhua) Space shuttle Discovery is cleared for return home after engineers determined that its heat shield was free of damage, said an official at NASA's mission control in Houston.

The ship's TPS (thermal protection system) is "100 percent clear for entry", mission control told Discovery Commander Steven Lindsey Sunday.

"That is great news, that's fantastic," Lindsey replied. "And to get all that done by the end of flight day six ... is just amazing."

Engineers examined a two-inch-long piece of fabric gap filler sticking out from thermal tiles on Discovery's belly, which could have required a spacewalk for repairs.

They concluded that astronauts would not need to conduct a spacewalk to pluck the filler out, as it posed no threat for the shuttle's return to Earth.

On Sunday, the astronauts continued to move fresh supplies to the International Space Station.

They conducted a spacewalk Saturday to test a robotic arm extension, which was seen as a success.

Discovery will have a last check-up at the end of the mission to ensure its safe return to Earth, which is scheduled July 17.

--Xinhua