The Payload Operations Center (POC) is the science command post for the International Space Station (ISS). Located at NASA's Marshall Space Flight Center in Huntsville, Alabama, it is the focal point for American and international science activities aboard the ISS. The POC's unique capabilities allow science experts and researchers around the world to perform cutting-edge science in the unique microgravity environment of space. The POC is staffed around the clock by shifts of payload flight controllers. At any given time, 8 to 10 flight controllers are on consoles operating, plarning for, and controlling various systems and payloads. This photograph shows a Payload Rack Officer (PRO) at a work station. The PRO is linked by a computer to all payload racks aboard the ISS. The PRO monitors and configures the resources and environment for science experiments including EXPRESS Racks, multiple-payload racks designed for commercial payloads.