NASA said Friday it has postponed the launch of the Endeavour for one day because of extra work needed to fix a cabin leak in the space shuttle.

A worker checks the movement of one of Endeavour's payload bay doors as it closes last week.
(Charisse Nahser/NASA)

Endeavour is now scheduled to lift off from the Kennedy Space Center in Florida on Wednesday at 6:36 p.m. instead of the planned Tuesday launch.

NASA said the leak, first discovered over the weekend, has been fixed. The problem was traced to a faulty pressure-relief valve designed to ensure the cabin does not become overpressurized. It has since been replaced, but not before NASA ran out of time to meet a Tuesday launch.

Making the trip to the International Space Station aboard the shuttle is school teacher-turned-astronaut Barbara Morgan, who was Christa McAuliffe's backup in 1986. McAuliffe was killed along with six others when the Challenger broke up shortly after liftoff.

The crew also includes 53-year-old Saskatoon-born astronaut Dave Williams, who is scheduled to take three spacewalks, one more than any Canadian before him.

The Canadian Space Agency and Saskatchewan's Ministry of Learning have arranged for students from four schools in La Ronge in northern Saskatchewan to ask Williams questions via a real-time video link as he orbits Earth.

The shuttle crew will work to complete assembly of the orbiting space station, installing the third starboard truss segment, a 2,200-kilogram piece that is a key building block in the station's solar panel array.

With files from the Associated Press