Space Shuttle Endeavour's final launch - and the next-to-last in the 30-year Shuttle programme - will come no earlier than 10 May; STS-134 had been set to launch to the International Space Station on 29 April, but lift-off was scrubbed with 4h to go owing problems with an auxiliary power unit.
Plans are for Shuttle programme and International Space Station managers to meet on 6 May to determine a more definite launch date after a faulty electrical load control assembly box in the Orbiter's aft compartment is replaced and the retest of systems has been completed.
Space Shuttle Endeavour's final launch will come no earlier than 10 May
STS-134's key payload is the European Space Agency-built Alpha Magnetic Spectrometer, a state-of-the-art particle physics detector designed to analyse cosmic radiation including anti-matter particles and search for so-called "dark" matter. The experiment will supplement the work being done at CERN's Large Hadron Collider in Geneva on the origin and structure of the Universe.
Following Endeavour's return to Earth, there will be just one remaining Shuttle mission, Atlantis's STS-135 flight scheduled for lift-off on 28 June carrying ESA's Raffaello multipurpose logistics module to deliver supplies and spare parts to the ISS.