Parsons, 46, is currently director of the Stennis space centre in Mississippi. He worked previously at the Kennedy Space Centre in Florida, and the Johnson centre in Houston, where he was deputy director.

In his new post Parsons will return to Houston, where his key task will be to restart the shuttle program following the Columbia disaster.

Columbia disintegrated just sixteen minutes away from landing as it re-entered Earth's atmosphere on February 1, killing all seven astronauts on board.

The shuttle programme has been suspended ever since.

"This is a big challenge for me," Parsons told journalists, adding he felt "quite a lot of trepidation" in taking on his new responsibilities.

"I have a reputation for being a good listener. If things need to be changed, we'll change them. But at this point, we'll stick with what we know," he said.

Michael Kostelnik, Deputy Associate Administrator for the Space Shuttle and International Space Station Programs, called Parsons "a natural born leader."

"We could not have asked for a better candidate," he said.

Parsons and Dittemore would work in tandem for a while to ensure a smooth transition. A final handover date was still to be fixed, Kostelnik added.

Dittemore, who had been with NASA for 26 years, announced his resignation at the end of April.

His decision predated the Columbia disaster, and he had delayed his departure in order to deal with the aftermath of the tragedy, he said.

SPACE.WIRE