KENNEDY SPACE CENTER, FLA. -- From inside the payload changeout room on the rotating service structure on Launch Pad 39B, the multi-purpose logistics module Leonardo is being moved into Space Shuttle Discovery's payload bay. The payload ground-handling mechanism (PGHM) is used to transfer the module into the payload bay. Leonardo is a reusable logistics carrier. It is the primary delivery system used to resupply and return station cargo requiring a pressurized environment. Leonardo is part of the payload on mission STS-121. Other payloads include the integrated cargo carrier with the mobile transporter reel assembly and a spare pump module, and the lightweight multi-purpose experiment support structure carrier. Discovery is scheduled to launch in a window extending from July 1 through July 19. Photo credit: NASA/Jack Pfaller

KENNEDY SPACE CENTER, FLA. -- From inside the payload changeout room on the rotating service structure on Launch Pad 39B, the multi-purpose logistics module Leonardo is lowered into Space Shuttle Discovery's payload bay. The payload ground-handling mechanism (PGHM) is used to transfer the module into the payload bay. Leonardo is a reusable logistics carrier. It is the primary delivery system used to resupply and return station cargo requiring a pressurized environment. Leonardo is part of the payload on mission STS-121. Other payloads include the integrated cargo carrier with the mobile transporter reel assembly and a spare pump module, and the lightweight multi-purpose experiment support structure carrier. Discovery is scheduled to launch in a window extending from July 1 through July 19. Photo credit: NASA/Jack Pfaller

KENNEDY SPACE CENTER, FLA. -- From inside the payload changeout room on the rotating service structure on Launch Pad 39B, the multi-purpose logistics module Leonardo is being moved into Space Shuttle Discovery's payload bay (at left). The payload ground-handling mechanism (PGHM) is used to transfer the module into the payload bay. Leonardo is a reusable logistics carrier. It is the primary delivery system used to resupply and return station cargo requiring a pressurized environment. Leonardo is part of the payload on mission STS-121. Other payloads include the integrated cargo carrier with the mobile transporter reel assembly and a spare pump module, and the lightweight multi-purpose experiment support structure carrier. Discovery is scheduled to launch in a window extending from July 1 through July 19. Photo credit: NASA/Jack Pfaller

KENNEDY SPACE CENTER, FLA. -- From inside the payload changeout room on the rotating service structure on Launch Pad 39B, workers maneuver the multi-purpose logistics module Leonardo into Space Shuttle Discovery's payload bay (at left). The payload ground-handling mechanism (PGHM) is used to transfer the module into the payload bay. Leonardo is a reusable logistics carrier. It is the primary delivery system used to resupply and return station cargo requiring a pressurized environment. Leonardo is part of the payload on mission STS-121. Other payloads include the integrated cargo carrier with the mobile transporter reel assembly and a spare pump module, and the lightweight multi-purpose experiment support structure carrier. Discovery is scheduled to launch in a window extending from July 1 through July 19. Photo credit: NASA/Jack Pfaller