Houston: While Discovery astronauts are still in the orbit busy rejuvenating the International Space Station's air system, NASA is gearing up space shuttle Endeavour for an historic final trip to the launch pad.

Shuttle Endeavour has been moved from maintenance hanger to vehicle assembly building at the Kennedy Space Center in Florida to get attached to the fuel tank and rocket booster that will help its final space voyage on April 19.

NASA plans to roll Endeavour out to its seaside launch pad for the final time on Wednesday, the day Discovery, flying a last mission of its own, is due to land at the Kennedy Space Center's landing strip.

Initially, Discovery was slated to land on March 8 with Endeavour moving to the launch the next day. NASA is retiring its three winged orbiters later this year after 30 years of shuttle flight.

Discovery's current mission launched on February 24, beginning what is now a 13-day mission to deliver a storage room and humanoid robot, called Robonaut 2, to the International Space Station.

After Discovery's mission ends, NASA plans to fly just two more flights before shutting down the shuttle programme.

The final flight of Endeavour is currently set to launch on April 19 to deliver a USD 1.5 billion astrophysics experiment to the International Space Station.