Tracking And Data Relay Satellite (TDRS) Constellation Network.

What is the Tracking and Data Relay Satellite Network? Established in 1973, the Tracking and Data Relay Satellite (TDRS) project was started to provided continuous, around the clock communications to NASA’s low Earth orbiting (LEO) missions. The idea of a space based communications network came about because of the high costs of maintaining a worldwide network of ground stations. These ground stations were also inefficient compared to the space based satellite constellation.

NASA launched the first TDRS satellite in 1983 aboard the Space Shuttle Challenger and have been launching newer TDRS satellites since. Most of the satellites in the network are still in operation today, and a few are exceeding their life expectancy. 

The Tracking and Data Relay Satellite network consist of three generations of satellites. The first generation of satellites, A through G, were launched aboard various Space Shuttles from 1983-1995. The second generation satellites H, I and J, were launched aboard Atlas IIA rockets between 2000 and 2003. Lastly, the third gen satellites, K, L and M, are launching on the United Launch Alliance Atlas V rockets. 

Tracking and Data Relay Satellite Program LogoThe TDRS constellation orbits above Earth at an altitude of 22,300 miles. Satellites placed in an orbit this high above Earth will travel at the same speed as our blue planet rotates. This allows the satellites to continuously remain in view of the same location on Earth. With TDRS in three precise locations around Earth, the satellite constellation can provide 100 percent coverage.

Types of Antennas

The TDRS satellite can communicate using two different types of antennas. The single access antenna system and the multiple access antenna system. The single access antenna are large parabolic-style antenna, while the multiple access are phased array antennas. 

Engineers deployed TDRS-M’s antennas during a routine test at Boeing’s plant in El Segundo, California.
Engineers deployed TDRS-M’s antennas during a routine test at Boeing’s plant in El Segundo, California.
Credits: Boeing

The Single Access Antenna:
Two 15-foot diameter mechanically steerable antennas. They offer a range of frequencies including S, Ku, and Ka-band to provide high gain support to satellites low gain antennas. 

The Multiple Access Antennas:
These are phased array antennas which are designed to receive signals from up to five spacecraft at a time in the S-band frequency. This provides a demand access capability to the satellite.

TDRS Constellation Communications Services.

NASA’s Tracking and Data Relay Satellite constellation provides communication services to more than 35 low Earth orbiting (LEO) missions, ensuring almost continuous global communications coverage to missions that need this kind of service. Missions such as the Hubble Space Telescope and the International Space Station (ISS) depend on the TDRS’s reliability. 


TDRS first generation satellite
First Generation TDRS. Credit: NASA
second generation tracking and data relay satellite
Second generation tracking and data relay satellite. Credit NASA
third generation tracking and data relay satellite
Third Generation TDRS. Credit: NASA

First Generation Launches

SatelliteLaunch DateRocketLaunch SiteStaus
TDRS-AApril 4, 1983Space Shuttle Challenger (STS-6)LC-39ARetired 2010
TDRS-BJan. 28, 1986Space Shuttle Challenger (STS-51)LC-39BDestroyed
TDRS-CSept. 29, 1988Space Shuttle Discovery (STS-29)LC-39BIn Storage 2011
TDRS-DMarch 13, 1989Space Shuttle Discovery (STS-29)LC-39BRetired 2012
TDRS-EAugust 2, 1991Space Shuttle Atlantis (STS-43)LC-39AIn Storage
TDRS-FJan. 13, 1993Space Shuttle Endeavour (STS-54)LC-39BActive
TDRS-GJuly 13, 1995Space Shuttle Discovery (STS-70)LC-39BActive

Second Generation Launches

SatelliteLaunch DateRocketLaunch SiteStaus
TDRS-HJune 30, 2000Atlas IIASLC-36AActive
TDRS-IMarch 8, 2002Atlas IIASLC-36AActive
TDRS-JDec. 5, 2002Atlas IIASLC-36AActive

Third Generation Satellites

SatelliteLaunch DateRocketLaunch SiteStatus
TDRS-KJan. 31, 2013Atlas V 401SLC-41Active
TDRS-LJan. 24, 2014Atlas V 401SLC-41Active
TDRS-MAugust 3, 2017Atlas V 401SLC-41TBD
TDRS-NTBDTBDTBDTBD

 

 

Tracking and Data Relay Fl

 

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