NASA delays shuttle flight

NASA has delayed the space shuttle's return to flight one week in order to finish work on several safety modifications made in the aftermath of the Columbia disaster.

Launch of the comeback mission - NASA's first in more than two years - is now set for May 22. Discovery is poised for liftoff with seven astronauts on a 12-day flight to supply the International Space Station and test shuttle design changes.

"We were really pushing to get to [May 15]," shuttle program manager Bill Parsons said at the Florida launch site Wednesday. Parsons said in a telephone news conference that he ordered the launch delay in keeping with NASA's post-Columbia vow not to let schedules get in the way of safety.

NASA officials had just concluded a technical review of 20 major safety improvements made since February 2003 with the goal of preventing a breakup like the one that killed seven astronauts and destroyed their spaceship.

Four items--three changes to the shuttle's external fuel tank and the addition of a camera-laden boom for inspecting the shuttle's heat shield--need more engineering analysis before they can be certified as ready to fly, NASA officials determined.

Columbia was brought down by a heat shield breach, created when a chunk of fuel tank insulation struck its left wing as the shuttle was launching. Accident investigators ordered NASA to redesign the fuel tank to eliminate debris sources and to develop a way to inspect and repair the shuttle's heat shield in flight.

The remaining analyses amount mostly to a stack of what NASA calls "close-out paper," but deputy program manager Wayne Hale, chairman of NASA's mission management team, declined to characterize the paperwork as a bureaucratic problem. "It's good engineering process," he told reporters.

Some of that paperwork will help to satisfy demands of an outside panel that is tracking NASA's progress implementing recommendations of the Columbia Accident Investigation Board. Fifteen of the board's recommendations were categorized as return-to-flight requirements. NASA had complied fully with only seven in late March. That was the last time the review panel, run by former astronauts Richard Covey and Thomas Stafford, made a public statement.

The launch delay will allow NASA more time to prepare its case for the Stafford-Covey Return to Flight Task Group. Parsons said officials expect to make their final presentation to the group from May 4 to May 6. The agency also has one more internal review to complete by April 27.

The Stafford-Covey panel previously said it would issue its final report on NASA's progress at least one month before the shuttle is launched. It isn't clear whether the space agency is willing to wait for the report. NASA Administrator Michael Griffin this week said he will consider launching over the task group's objections if senior shuttle managers convince him it is safe to do so.

The current launch "window" closes June 3. Another opportunity will not come until mid-July.