At the GSFC Network Integration Center, Goddard employees work to guarantee Shuttle Astronauts have continuous open lines of communication with Kennedy Space Center and Johnson Space Center's Mission Control. The work done at the NIC also allows Mission Control to monitor the performance of thousands of systems on the Shuttle, send flight commands and relay science data. The NIC is staffed 24 hours a day during human space flight missions and has served as the critical communication hub for each of the 135 Shuttle missions.