Spotlight | Tracking and Data Relay Satellite System
SAN FRANCISCO — NASA is preparing to take an important step in revitalizing the key network U.S. government agencies rely on to control the position of satellites operating in low Earth orbit and transmit data between spacecraft and ground stations with its planned late January launch of a data relay satellite. The satellite, known as TDRS-K, will be the first in more than a decade to join NASA’s Tracking and Data Relay Satellite System (TDRSS), also known as the Space Network.
The launch of TDRS-K, which originally was slated for a Dec. 13 flight aboard aAtlas 5 rocket from Cape Canaveral Air Force Station in Florida, slipped to late January due to range delays associated with the investigation of an upper-stage engine anomaly detected during the Oct. 4 launch of a GPS satellite. Government officials are eagerly awaiting the launch of TDRS-K and its twin, TDRS-L, which is set to launch in 2014, because many of the TDRSS satellites currently in orbit are well beyond their anticipated lifespan.
Since NASA sent the first TDRSS satellite into geosynchronous orbit from the Space Shuttle Challenger in 1983, the space agency has launched a total of 10 TDRSS spacecraft. Of those, one was destroyed during the 1986 Challenger disaster and two more were retired after more than two decades of operations. In a 2010 report, the NASA inspector general warned that without TDRS-K and TDRS-L “there could be insufficient tracking capability to support NASA and other Government and non-Government missions as early as 2011.”
TDRSS at a Glance
Mission: To provide round-the-clock tracking, data, voice and video communication services to NASA robotic and human spaceflight missions as well as expendable launch vehicles, satellites and space cargo ships operated by commercial firms, international space agencies and U.S. government agencies, including the Defense Department’s Missile Defense Agency and the National Oceanic and Atmospheric Administration.
History: First TDRSS ground station established in White Sands, N.M., in 1981. First satellite launched in 1983.
Components: Seven satellites in geosynchronous orbit, a network control center at NASA’s Goddard Space Flight Center in Greenbelt, Md., and ground terminals in Guam and White Sands.
Managed by: NASA’s Goddard Space Flight Center under the direction of the Space Communications and Navigation Office at NASA headquarters.
In spite of that warning, TDRSS has continued to provide service to its customers with two satellites over the Pacific Ocean, two over the Atlantic Ocean, two over the Indian Ocean and one on-orbit spare. Still, NASA officials are eager to update the TDRSS constellation. In 2007, NASA awarded a $696 million contract to Boeing Defense, Space & Security of El Segundo, Calif., to build TDRS-K and TDRS-L. That contract included options for TDRS-M and TDRS-N. In November 2011, NASA exercised its option to buy TDRS-M at a cost of $289 million. NASA officials are in negotiations with Boeing to purchase TDRS-N under a contract option set to expire on Nov. 30, 2012, NASA spokeswoman Rachel Kraft said in a Nov. 20 email.
Boeing completed construction of TDRS-K in early October. The company is storing that satellite, which will be shipped to Cape Canaveral approximately 45 days before its launch, said John Leuer, Boeing’s TDRS program director. Boeing also plans to complete environmental testing of the TDRS-L spacecraft in December, Leuer added. TDRS-L is scheduled to launch in late January 2014, said Jeff Gramling, TDRS project manager at NASA’s Goddard Space Flight Center in Greenbelt, Md.
Although the new TDRSS satellites are similar to their predecessors, they offer increased bandwidth, which will enable NASA to support additional U.S. missions and missions conducted by the space agency’s international partners, Kraft said. TDRSS already provides tracking and data services for robotic cargo ships, including Europe’s Automated Transfer Vehicle and the Japan Aerospace Exploration Agency’s H-2 Transfer Vehicle.
The new satellites also employ different beam-forming technology and updated electronics from the previous generation of data-relay satellites. When NASA ordered TDRS-K, -L and -M, the space agency directed Boeing to build satellites that support ground-based beam-forming for the S-band phased array antenna as opposed to on-board beam-forming, which was featured in TDRS-H, -I and -J, also built by Boeing, Gramling said. Due to the lengthy gap in satellite production, many of the parts used in earlier data relay satellites were no longer available. “All of the payload equipment had to be redesigned,” Gramling said. Boeing built TDRS-H, -I and -J in the 1990s. Those three satellites, which were designed to operate in orbit for 11 years, were launched in June 2000, March 2002 and December 2002, respectively.
While Boeing builds and tests the new TDRS spacecraft, General Dynamics C4 Systems of Scottsdale, Ariz., is leading a team of companies working to update the Space Network’s ground stations in Guam and White Sands, N.M., and establish a new facility in Blossom Point, Md., under a seven-year contract awarded in 2010 that could be worth $642.2 million if all contract options are exercised.
NASA’s Space Communications and Navigation Program, meanwhile, is looking beyond TDRSS. In 2012, NASA officials began an initial concept study to develop the top-level architecture and define requirements for the follow-on to TDRSS. “The system may include enhanced capabilities such as higher-rate optical and Ka-band phased array technologies, space inter-|networking and smarter buses to provide service at lower cost,” Kraft said in an emailed response to questions. “Different service acquisition and business models, such as hosted payloads, are also being evaluated. The study is planned to lead to a procurement and development program to provide space relay services starting early in the next decade depending on the exercise of the TDRS-N option.”