Tracking and Data Relay Satellite System - Ground Segment

Ground Segment

The ground segment of TDRSS consists of two ground stations located at the White Sands Complex (WSC), the Guam Remote Ground Terminal (GRGT), and Network Control Center located at Goddard Space Flight Center in Greenbelt, Maryland. These three stations are the ‘heart’ of the network, providing command & control services. Under a system upgrade due to be completed by the end of 2016, a new terminal will be built at Blossom Point, Maryland.

WSC, located near Las Cruces consists of:

• White Sands Ground Terminal (WSGT)32°30′03″N 106°36′31″W / 32.5007°N 106.6086°W / 32.5007; -106.6086
• Second TDRSS Ground Terminal (STGT)32°32′35″N 106°36′43″W / 32.5430°N 106.6120°W / 32.5430; -106.6120
• Extended TDRS Ground Terminal (ETGT)

Additionally, the WSC remotely controls the GRGT on Guam.

The WSC has its own exit from U.S. Route 70 that is for facility staff only. NASA decided on the location of the ground terminals using very specific criteria. Foremost was the ground station’s view of the satellites; the location had to be close enough to the equator to view the skies, both east and west. Weather was another important factor – New Mexico has, on average, almost 350 days of sunshine per year, with a very low precipitation level.

WSGT went online in 1978, just in time for the space shuttle’s planned debut in early 1979. STGT became operational in 1994, completing the system after Flight-6’s on-orbit checkout earlier in the year. Additionally, after completion of the second terminal, NASA held a contest to name the two stations. Local middle school students chose Cacique (kah-see-keh), meaning “leader” for WSGT, and Danzante meaning “dancer” for STGT. These names seem to have been for publicity purposes only, for official NASA documentation use WSGT and STGT or WSC as designators.

WSGT and STGT are geographically separated and completely independent of one another, while retaining a backup fiber-optic link to transfer data between sites in case of emergency. Each ground station has 19-meter dishes, known as Space-Ground Link Terminals (SGLT), to communicate with the satellites. Three SGLTs are located at STGT, but only two are located at WSGT. The system architects moved remaining SGLT to Guam to provide full network support for the satellite covering the ZOE. Considered a remote part of the WSGT, the distance and location of the SGLT is transparent to network users.

The Guam Remote Ground Terminal (GRGT)13°36′53″N 144°51′23″E / 13.6148°N 144.8565°E / 13.6148; 144.8565 is an extension of the WSGT. The terminal contains SGLT 6, with the Communication Service Controller (CSC) located at WSGT’s TDRS Operations Control Center (TOCC). Before the GRGT was operational, an auxiliary system was located at Diego Garcia.