The free-flying Tracking and Data Relay Satellite-E (TDRS-E), still attached to an Inertial Upper Stage (IUS), was photographed by one of the crewmembers during the STS-43 mission. The TDRS-E was boosted by the IUS into geosynchronous orbit and positioned to remain stationary 22,400 miles above the Pacific Ocean southwest of Hawaii. The TDRS system provides almost uninterrupted communications with Earth-orbiting Shuttles and satellites, and had replaced the intermittent coverage provided by globe-encircling ground tracking stations used during the early space program. The TDRS can transmit and receive data, and track a user spacecraft in a low Earth orbit. The IUS is an unmarned transportation system designed to ferry payloads from low Earth orbit to higher orbits that are unattainable by the Shuttle. The Space Shuttle Orbiter Atlantis for the STS-43 mission was launched on August 2, 1991.
