NASA chose Satellite Development Center on Feb. 23, 1995, to build three next-generation Tracking and Data Relay Satellites (TDRS). The award ended a hard-fought, 8-year competition and restored the company's association with NASA after a 9-year interval. A trio of Boeing 601 model spacecraft will replace an aging constellation and serve as the primary means of continuous, high-data-rate communication with the Space Shuttle, with the International Space Station, and with dozens of unmanned scientific satellites in low-Earth orbit. The new satellites will augment the system's existing S- and Ku-band frequencies by adding Ka-band capability.