The Payload Operations Center (POC) is the science command post for the International Space Station (ISS). Located at NASA's Marshall Space Flight Center (MSFC) 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 the Command and Payload Multiplexer/Demultiplexer (MDM) Officers (CPO's) at their work stations. The CPO maintains the command link between the Operation Center at MSFC and Mission Control at Johnson Space Center in Houston, Texas, and configures the link to allow the international partners and remote scientists to operate their payloads from their home sites.