Shuttle will launch no earlier than May 10

Shuttle Endeavour won't set sail on its final flight before next Tuesday, May 10, at the earliest as Kennedy Space Center teams work to repair an electrical problem that scrubbed last Friday's launch attempt.

NASA had hoped a second attempt might be possible as soon as Sunday, but determined it would take about two more days than originally thought to ready the shuttle for another countdown.

"It became apparent Monday that more time was required," said Allard Beutel, a KSC spokesman.

Friday's launch scrubbed when heaters on a fuel line feeding part of the shuttle's hydraulic power system failed to turn on, a problem that could have led to a fire during flight.

An electronic switch box in the orbiter's engine compartment is believed to be at fault.

The box routes power to nine critical systems, from the auxiliary power units affected last week to the main engines and orbital thrusters.

Kennedy Space Center crews on Monday performed tests on the roughly 50-pound box and related components. They expected to have it removed by this morning and a replacement installed soon.

Extensive system tests will follow, requiring scaffolding and access platforms to be built inside Endeavour's aft compartment.

Before a launch countdown can begin, those platforms must be broken down and a number of other preparations completed, including reloading the orbiter's fuel cell system with propellants.