The announcement was made as the head of the shuttle program Ron Dittemore resigned from the National Aeronautics and Space Administration (NASA), though he insisted he had planned to quit before shuttle disintegrated on re-entry February 1, killing all seven crew on board.

"I think flying within a year of the event is possible," said Michael Kostelnik, NASA's deputy associate administrator for the shuttle program.

"Will it be likely or not, we'll have to wait and see what the board determines to be the cause, and the recommendations they make," he said.

Concern has been expressed that a prolonged suspension of the shuttle flights could affect the orbiting International Space Station (ISS).

"If we are able to return to flight in the January, February, March time frame, which hopefully is possible, that would take a lot of pressure off having to resupply" the ISS, the NASA administrator said.

Kostelnik's estimate of when flights could resume was more conservative than one last month in which he spoke of flights by the end of the year, but which he retracted last week.

The final word, he said would come from the Columbia Accident Investigation Board (CAIB), which is probing the reason the breakup of the shuttle as it hurtled toward its scheduled landing in Florida, and changes necessary to prevent a repetition.

The Orlando Sentinel newspaper in Florida has quoted internal NASA reports blaming the accident on a piece of foam insulation that dislodged from the shuttle on takeoff and damaged some of the shuttle's heat shield tiles.

According to the report, the damage allowed the super-heated gases generated on re-entry into the atmosphere to penetrate the shuttle skin causing the disintegration.

Kostelnik dismissed the report as "speculation from different media".

The resignation of the head of the shuttle program is a new blow as the agency awaits the result of the board's inquiry.

Dittemore, 51, who has been with NASA for 26 years, became the agency's public face during the briefings that followed the Columbia tragedy.

He said in a statement issued by NASA that his decision to leave was "a very difficult one, but it is a decision that I began struggling with long before the tragedy of the Columbia accident.

"The timing of my departure is based on what I believe will allow for the smoothest management transition possible, as the pace of work to return the shuttle to flight begins to ramp up."

Dittemore said he was leaving to join the private sector, but would remain until the CAIB finishes its investigation "and a complete return to flight path has been established."

Kostelnik said Dittemore had been "an integral part of the space shuttle program" for more than a quarter-century.

"I'm pleased Ron has decided to stay until our return to flight efforts are well established and I wish him the best as he begins a new chapter in his life."

SPACE.WIRE