NASA Announces Retirement of TDRS-4 Communications Satellite
May 9, 2012

NASA Announces Retirement of TDRS-4 Communications Satellite

After more than two decades of service, NASA on Wednesday announced that their Tracking and Data Relay Satellite 4 (TDRS-4) had completed its mission and was being retired from active service.

According to a statement released from the US space agency, the communications satellite had completed nearly 23 years of operational support -- far more than the 10 year operational life span it had been designed for -- and that it had successfully completed end-of-mission deorbiting and decommissioning activities.

TDRS-4, which was been launched in March 1989, operated in geosynchronous altitude, some 22,000 miles above the Atlantic Ocean, before it was decommissioned in November 2011. It was forced out of action after losing one of three Nickel-Cadmium (24 cell) batteries and experiencing reduced storage capacity for the remaining two. In order to retire the satellite, the excess fuel needed to be depleted, the batteries disconnected, and the Radio Frequency Transmitters and receivers powered down, in order to prevent future interference with other vehicles.

"This is the second retirement from within the fleet of TDRS," NASA said. "The fleet of seven remaining satellites operates through a supporting ground system and together they make up the Space Network (SN). The SN provides highly automated, user-driven services supporting customer spacecraft with tracking and data acquisition. The network supports a varied number of missions, including the International Space Station, Hubble Space Telescope, launch vehicles, and a variety of other science missions."

It also provided primary communication support to the recently-retired space shuttle program.

"The Space Network spacecraft engineering and operations teams worked together very effectively to execute a practically flawless decommissioning of an incredible satellite," Mike Rackley, SN deputy project manager at the Goddard Space Flight Center, said in a statement. "TDRS-4 made great and important contributions to NASA's human spaceflight and science missions. We will certainly miss her."