The crew includes five Americans and Italian astronaut Roberto Vittori.
"It's great to be back," said shuttle Cmdr. Mark Kelly, whose lawmaker wife Gabrielle Giffords is recovering from a bullet wound to the head but plans to attend Monday's launch at 8: 56 a.m.
"We really appreciate all the hard work by the team that's worked over the last couple of weeks to get shuttle Endeavour ready."
The initial launch attempt on April 29 was scrubbed hours before liftoff when technicians discovered a power failure in a heating line that served to prevent fuel from freezing in orbit.
U.S. space agency NASA said Monday engineers were confident that the problem would be fixed in time for launch on May 16. The blastoff will mark the penultimate mission to the International Space Station by a U.S. shuttle before the storied program formally ends later this year with the mission of Atlantis, the final space shuttle to retire.
Endeavour will carry a $2-billion, seven-tonne particle physics detector, the Alpha Magnetic Spectrometer-2, which will be left at the space station to scour the universe for dark matter and antimatter.
The 16-day mission, known as STS-134, is set to include four spacewalks.
The weather forecast for Monday's launch was 70 per cent favourable, NASA said.
read more: canada