NASA Tracking and Data Relay Satellite TDRS-H sits poised before its launch aboard an Atlas IIA Centaur rocket.

NASA’s Tracking and Data Relay Satellite (TDRS-H) sits poised on Launch Pad 36A, Cape Canaveral Air Force Station, before its scheduled launch aboard an Atlas IIA/Centaur rocket. One of three satellites (labeled H, I and J) being built by the Hughes Space and Communications Company, the latest TDRS uses an innovative springback antenna design. A pair of 15-foot-diameter, flexible mesh antenna reflectors fold up for launch, then spring back into their original cupped circular shape on orbit. The new satellites will augment the TDRS system’s existing Sand Ku-band frequencies by adding Ka-band capability. TDRS will serve as the sole means of continuous, high-data-rate communication with the space shuttle, with the International Space Station upon its completion, and with dozens of unmanned scientific satellites in low earth orbit