Engineers were worried about shuttle’s left wing prior to disaster

DISCLOSED e-mails inside NASA showed senior engineers worried a day before the Columbia disaster that the shuttle’s left wing might burn off and cause the deaths of the crew, a scenario remarkably similar to the one investigators believe actually occurred.

The dozens of pages of e-mails describe a broader, internal debate than previously acknowledged the seriousness of potential damage to Columbia from a liftoff collision with foam debris from its central fuel tank. Engineers never sent their warnings to the National Aeronautics and Space Administration's brass. Engineers in Texas and Virginia fretted about the shuttle's safety during its final three days in orbit.

One speculated whether officials were "just relegated to crossing their fingers", another questioned why such dire issues had been raised so late.

"Why are we talking about this on the day before landing and not the day after launch?" wrote William C Anderson, an employee for the United Space Alliance LLC, a NASA contractor, less than 24 hours before the shuttle broke apart February 1 while returning to Earth.

NASA said those messages were part of a "what-if" exercise by engineers convinced the shuttle would land safely despite possible damage from foam that struck insulating tiles on the spacecraft's left wing at liftoff.

In Washington, NASA administrator Sean O'Keefe was set to appear at an appropriations hearing last night. He wrote to the House Science Committee in prepared testimony that the independent board investigating the disaster "has made significant progress in organising its work to determine the cause of the accident".

The engineers' e-mails also showed the space agency was sufficiently concerned about possible damage to Columbia that it asked the Defence Department then abruptly changed its mind to take pictures of the shuttle in orbit more than one week before its breakup.

The request came six days into the mission, on January 22.

For weeks until Wednesday, NASA has denied it ever made such a request.

The space agency withdrew its informal request one day later amid fears it might have "cried wolf" and endangered future such requests, according to one e-mail.

Deciding against the satellite request, a space official wrote reassuringly to the Defence Department that Columbia was "in excellent shape" and that insulating foam that struck the shuttle on its mid-January liftoff was "not considered to be a major problem".