Endeavour's Final Payload Headed To Pad

NASA retracted a giant service structure at Kennedy Space Center's launch pad 39A today, setting the stage of the delivery tonight of the prime payload for shuttle Endeavour's 25th and final flight.

The $1.5 billion Alpha Magnetic Spectrometer will arrive in a payload canister that will be hoisted with a crane into the Payload Changeout Room at the launch pad. The 14,800-pound particle physics experiment will be grappled with a giant ground handling mechanism on Tuesday and then installed in Endeavour's cargo bay on Friday.

You can learn more about the cosmic ray detector HERE and HERE.

Call To Stations for the payload move is scheduled for 6 p.m. tonight.

The payload delivery will follow the completion over the weekend of a critical propellant-loading operation. Toxic rocket propellants were loaded into onboard tanks that feed Endeavour's twin maneuvering engines as well as the ship's 44 nose-and-tail steering jets. The shuttle's three Auxiliary Power Units also were fueled for flight.

Endeavour and six astronauts remain scheduled for launch at 7:48 p.m. April 19. Four spacewalks are planned during a 14-day mission that is scheduled to conclude with a 1:27 p.m. May 3 landing at KSC's three-mile shuttle runway.