Space shuttle Endeavour STS-134 commander Mark Kelly (C) waves while departing for launch pad 39A with crew members

Cape Canaveral - Nasa on Monday delayed the launch of space shuttle Endeavour to April 29 from April 19 because of a scheduling conflict at the International Space Station.

Endeavour's mission will be the second-to-last for Nasa’s shuttle program and will deliver a $2 billion particle detector called the Alpha Magnetic Spectrometer to the orbital outpost.

Nasa pushed back the launch date to avoid having Endeavour's mission overlap with the arrival of a Russian cargo ship at the station - a $100 billion project of 16 nations which orbits about 220 miles (354km) above Earth.

Nasa officials had hoped the unmanned Progress, which is carrying cargo and science experiments, could loiter in orbit until Endeavour's scheduled May 1 departure from the space station.

But the Progress is carrying a biological experiment that cannot linger in orbit, Nasa spokesman Allard Beutel said.

“We saw this coming and have been working (the issue) for a while,” he said.

In a meeting on Sunday, space station managers agreed to postpone Endeavour's 14-day mission to resolve the conflict.

The particle detector travelling aboard Endeavour will be mounted outside the space station to look for new forms of matter - and possibly antimatter.

The shuttle crew is led by Mark Kelly, husband of Arizona Congresswoman Gabrielle Giffords, who is recovering from a Jan. 8 gunshot wound to the head. Kelly has said that his wife is planning to attend the launch.

Giffords is undergoing rehabilitation at a Houston hospital. She has not been seen in public since the shooting outside a Tucson grocery store that left six dead and 12 others injured. - Reuters