The payload bay doors were opened for the first time today using the orbiter's onboard door operation system.

The payload bay doors of the Space Shuttle Orbiter Columbia were opened for the first time today using the orbiter's onboard door operation system. The hinges of the payload bay doors are not designed to support the weight of the doors while open horizontally in the Earth's one 'g' environment and a counterweight zero 'g' device supports the weight of the doors while they are open for processing in the OPF.