The primary payload of the STS-43 mission, Tracking and Data Relay Satellite-E (TDRS-E) attached to an Inertial Upper Stage (IUS) was photographed at the moment of its release from the cargo bay of the Space Shuttle Orbiter Atlantis. 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 launch of STS-43 occurred on August 2, 1991.
