The Marshall Space Flight Center (MSFC) is the U.S. government's civilian rocketry and spacecraft propulsion research center. The largest NASA center, MSFC's first mission was developing the Saturn launch vehicles for the Apollo moon program. Marshall has been the agency's lead center for Space Shuttle propulsion and its external tank; payloads and related crew training; International Space Station (ISS) design and assembly; and computers, networks, and information management.