Nasa officials were warned of a large gash on the heat protection tiles on the Columbia in an internal memo two days before the space shuttle broke apart in the skies above Texas.
The memo, which emerged yesterday, raised troubling questions about whether anything could have been done to prevent the disaster that claimed the lives of all seven astronauts on board on Saturday morning.
The warning, first reported on the US news network MSNBC, was from a Nasa engineer who said there was a 76 x 19cm area of damaged or missing tiles on the left wing. At least one tile was totally gone, the memo said. Video footage appeared to show a substantial dent in the wing.
A key focus of investigations is a piece of insulation foam that tore off a large external engine and collided with the left wing 80 seconds after launch and may have exposed the metal skin beneath the tiles. The craft is covered with thousands of tiles to resist the searing heat of re-entry.
Shortly before the shuttle broke up, Nasa computers had recorded a 15,5C spike in temperature on the left-hand side of the craft and reported a drag on the wing, indicating a damaged or missing tile.
At a briefing in Washington, Nasa’s deputy administrator, General Michael Kostelnik, said the space agency would re-examine the memo. But he reiterated comments that Nasa has made since the disaster three days ago that ”the best and the brightest” in mission control in Houston, Texas, had studied the incident during launch and decided it had not presented any danger to the shuttle.
The internal memo, pointing to the gash, said it presented ”no burn through and no safety of flight issues”.
Gen Kostelnik said: ”This is not a new phenomenon. We have seen this happen before and in no other case has there been a major safety issue.”
Nasa is still looking at other possible avenues, including problems with the structure of the craft or navigation controls, but has conceded that early evidence pointed to a ”thermal” problem as the Columbia faced temperatures of 1 650C.
Bill Readdy, an associate administrator, said: ”Everyone has leaped to the conclusion that was the cause. I’m not ready to say that.” But he added: ”That is certainly the leading candidate right now.”
Nasa maintains that little could have been done to repair the tiles even if they had been felt to be a potential hazard. A space walk to examine the area underneath the wing could have caused further damage, the agency said.
The search for clues will include a further 32 seconds of data from the moments before the Columbia disintegrated. The data came in a flawed signal but engineers are attempting to interrogate it to get a better idea of what happened. The head of Nasa, Sean O’Keafe, briefed President George Bush on developments in the investigation.
Yesterday there was continued criticism of cuts to Nasa’s budgets that some former astronauts have claimed may have put missions in jeopardy. – Guardian Unlimited Â