Nasa team feared shuttle wing failure

Nasa engineers sent emails the day before the Columbia disaster expressing their fears that the space shuttle's wing might burn off, killing the astronauts inside, according to records released by the space agency last night.

"Why are we talking about this on the day before landing and not the day after launch?" wrote William Anderson, an engineer for United Space Alliance, a Nasa subcontractor, referring to fears that damage caused to the craft's left wing during launch might allow superheated air to burn through its fuselage.

The documents, released under US freedom of information legislation, show engineers at Nasa's Langley research centre in Virginia engaged in a frenetic series of phone calls and emails in the 24 hours before Columbia burned up during re-entry on February 1, killing the crew of six Americans and one Israeli.

At mission control at the Johnson space centre in Houston, Texas, a flight controller, Jeffrey Kling, made contingency plans for a blaze in the shuttle's wheel compartment, suggesting in an email that if that occurred, Nasa should "set up for a bailout (assuming the wing doesn't burn off before we can get the crew out)".

But the engineers decided not to inform senior Nasa executives on the level of Ron Dittemore, the shuttle programme manager, who could have ordered the plans to be enacted.

The engineers' fears provide a persuasive account of what may have happened to Columbia because a loss of data from the left wing was the main warning to mission control that something on board was badly wrong.

In one email, shuttle engineer Kevin McCluney explored the possibility of "LOCV" - loss of crew and vehicle - but said that only a total loss of data from sensors on the wing would justify considering whether to bail out or proceed with a potentially fatal landing.

Writing to Mr Dittemore after the disaster, when the requests were made for the emails, Nasa employee Robert Doremus said the engineers were "doing a 'what-if' discussion and ... we all expected a safe entry".

On Tuesday, the board investigating the disaster said it wanted to discover more about an unidentified object, about 1ft square and 4in deep, that probably fell off the shuttle and could be seen flying alongside it.

A videotape, apparently recovered in Texas, showing footage recorded inside the craft, stops four minutes before the disaster and shows the crew behaving normally.