STS131-S-054 (5 April 2010) --- Bill Gerstenmaier, associate administrator for Space Operations, intently watches the progress of space shuttle Discovery's STS-131 mission launch countdown in Firing Room 4 in the Launch Control Center at NASA's Kennedy Space Center in Florida. The seven-member STS-131 crew will deliver the multi-purpose logistics module Leonardo, filled with supplies, a new crew sleeping quarters and science racks that will be transferred to the International Space Station's laboratories. The crew also will switch out a gyroscope on the station’s truss structure, install a spare ammonia storage tank and retrieve a Japanese experiment from the station’s exterior. STS-131 is the 33rd shuttle mission to the station and the 131st shuttle mission overall.