The US space shuttle Endeavour has prepared to undock from the International Space Station and jet back to Earth, wrapping up its final journey. NASA said the six-member crew of the Endeavour on Sunday bid farewell to three astronaut colleagues on board the space station and closed the hatches between the shuttle and station. Endeavour's 16-day mission began with the shuttle's launch from Cape Canaveral, Florida on May 16. During the mission, the team delivered and installed a massive physics experiment, the Alpha-Magnetic Spectrometer-2, that will be left at the space station to scour the universe for clues about dark matter and antimatter. They also brought up a logistics carrier with spare parts for the orbiting lab and performed some maintenance and installation work during four spacewalks. Endeavour is scheduled to land at Kennedy Space Center at 2:35 am local time on Wednesday, carrying its crew of five US astronauts and Italian Roberto Vittori.