Satellites are expensive, and once in orbit they cannot be fixed. This is why a satellite must be tested thoroughly before it is sent into space. During the various phases of its development a satellite and its component parts undergo extensive testing. The majority of ESA spacecraft are tested in the ESTEC Test Centre, which is Europe's largest satellite testing site. But that's not all. While TEC is indeed responsible for ESA's longer-term technology development, an equally important part of its overall mission is supporting European (space and non-space) industry in their own research and development. TEC offers external parties a unique research and development infrastructure: hi-tech laboratories, test facilities and specialist sections focused on key engineering topics and encompassing every aspect of the space environment.