All 11 members of the US space agency's (Nasa) spaceflight security panel have resigned in the wake of criticism over the loss of the shuttle Columbia earlier this year.
The panel was created in 1967 after a fire broke out during preparations for the Apollo 1 mission, when three astronauts died.
Columbia's crew died as the shuttle disintegrated on re-entry
Members include space engineers, scientists, former aerospace industry executives and military officers.
But its effectiveness was questioned after Columbia broke up over Texas while re-entering the Earth's atmosphere, killing all seven astronauts on board.
The Columbia Accident Investigation Board (CAIB) said in its report on the disaster that the panel lacked influence.
And members of the Senate Appropriations Committee said the panel failed to spot potential danger signs in the operation of the orbiter and that Nasa should reconstitute the panel.
In a letter to Nasa administrator Sean O'Keefe announcing the resignations, panel chairwoman Shirley McCarty said: "This will give you and the Congress the freedom to revitalise the panel and reshape its charter and mission."
In a statement responding to the resignations, Mr O'Keefe said: "We need to take this opportunity to explore how the original concept for an Aerospace Safety Advisory Panel needs to evolve to best meet the future needs of the agency.
"A comprehensive review of the panel and its role in our safety objectives will be vital in the coming weeks as we move forward."
The CAIB report was highly critical of the agency, saying that management blunders were as much to blame as technical problems for the destruction of the shuttle.
The final conclusions of the inquiry reaffirmed the view that a breach of the shuttle's heat shield on take-off caused it to break up on re-entry.