April 4, 2013
NASA Celebrates 30th Anniversary Of First Satellite Communications Network
redOrbit Staff & Wire Reports - Your Universe Online
Thursday marked the 30th anniversary of the deployment of NASA´s first Tracking and Data Relay Satellite, TDRS-A, which was carried into space as part of space shuttle Challenger´s maiden voyage on April 4, 1983.
TDRS-A was deployed a day after the shuttle´s launch, as astronauts released the probe from Challenger´s cargo bay, officials from the US space agency said. Following 39 adjustment burns, it successfully achieved geosynchronous orbit around the equator, traveling more than 22,000 miles above the Earth´s surface. It would later be renamed TDRS-1 and kicked off what NASA officials called “a new era in spacecraft-to-ground communications.”
“The launch of the first TDRS spacecraft 30 years ago opened a new era for satellite communications,” Jeff Volosin, deputy associate director of exploration and space communication at NASA's Goddard Space Flight Center in Maryland, said in a statement. “This revolutionary network, the only one of its kind in the world, has enabled NASA's astronauts and robots to relay their outstanding scientific achievements to Earth.”
Initially, NASA had to rely upon ground stations at various locations throughout the world to serve as their communications network. At best, this network could support approximately 15 percent of a spacecraft´s orbit during the Mercury, Gemini and Apollo flights, the space agency explained.
In 1973, the TDRS project was established in order to come up with a new communications system that was less reliant on ground stations while providing long-duration communications coverage. That new design was to consist of geosynchronous communication satellites and a pair of ground stations, thus allowing NASA´s most critical low-Earth-orbiting spacecraft — including the newly launched fleet of space shuttles — to be in continuous communication with NASA officials. The network would support up to 26 user satellites at the same time.
The network would not process user traffic, but would operate like a “bent-pipe repeater” — taking an incoming radio frequency carrier wave signal, processing it so that it would be a different frequency and then beaming it back to Earth. TDRS would relay signals and data between spacecraft and ground terminals, while also significantly increasing the volume of data transmitted back to Earth and providing 100 percent coverage to low-Earth-orbiting spacecraft. It was also expected to reduce operating costs by eliminating extraneous ground stations.
According to NASA, TDRS-A was shipped to NASA´s Kennedy Space Center in Florida on November 14, 1982. At the time of its launch, it was “the largest, most sophisticated communication satellite ever built, weighing about 5,000 pounds.”
The full triangle-shaped network was officially completed with the 1989 deployment of TDRS-4. Eleven satellites have been built, 10 of which have become operational and one of which was lost during the space shuttle Challenger disaster in 1986. The second generation of the TDRS project ran from 2000 through 2002, when NASA launched the H, I and J satellites.
The third generation is currently underway, with the first of the next-gen TDRS spacecraft, TDRS-K, having been launched on January 30. TDRS-L is scheduled for a 2014 deployment, and the TDRS-M launch readiness date is currently listed as December 2015, according to NASA.
“Thirty years after the first launch, the TDRS network has become NASA's critical communication link in the agency's ability to support the continuing work of understanding our planet and beyond,” the space agency said.
Left Image Below: The maiden launch of space shuttle Challenger, which carried the first TDRS satellite to orbit. Credit: NASA
Right Image Below: TDRS-A (later renamed TDRS-1) being deployed from Challenger's cargo bay. Credit: NASA