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 the Timeline Change Officer (TCO) at a work station. The TCO maintains the daily schedule of science activities and work assignments, and works with planners at Mission Control at Johnson Space Center in Houston, Texas, to ensure payload activities are accommodated in overall ISS plans and schedules.