NASA said Thursday it was postponing the final two space shuttle launches before the program is phased out, citing a delay in needed equipment.
The US space agency set November 1 for the launch of space shuttle Discovery's STS-133 mission, which had been planned for September 16.
NASA said the shuttle Endeavour mission was rescheduled February 26 instead of late November.
"The target dates were adjusted because critical payload hardware for STS-133 will not be ready in time to support the previously planned September 16 launch," NASA said in a statement.
With the Discovery launch moving to November, the Endeavour mission "cannot fly as planned, so the next available launch window is in February 2011," NASA said, adding that the launch dates are subject to change.
The US space shuttles are being retired after President Barack Obama opted not to fund a successor program, deciding instead to encourage private spacecraft development.
The final two shuttle missions are both to the orbiting International Space Station (ISS).
The Endeavour's mission was already postponed from its original July 29 launch date to replace a part on the 1.5-billion-dollar Alpha Magnetic Spectrometer due for ISS delivery -- the device will delve into the mysterious dark matter thought to permeate the universe.
The Discovery mission will deliver replacement parts for the Italian-made Pressurized Multipurpose Module (PMM) Leonardo, which will be permanently attached to the ISS.
Once the shuttle program ends, the United States will rely on Russia's Soyuz rockets to carry its astronauts to the space station until a commercial US launcher can be developed. That is scheduled for 2015.
Copyright 2010 AFP Global Edition
