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The Tracking and Data Relay Satellite System (TDRSS) is a communication signal relay system which provides tracking and data acquisition services between low earth orbiting spacecraft and NASA/customer control and/or data processing facilities. The system is capable of transmitting to and receiving data from customer spacecrafts over 100% of their orbit (some limitations may apply depending on actual orbit).

The Goddard Space Flight Center receives programmatic direction from NASA Headquarters Office of Space Operations regarding all aspects of the Tracking and Data Relay Satellite System and the Space Network. At Goddard, the Space Communications Program Office, provides the day to day management and operations of TDRSS and the Space Network

The TDRSS space segment consists of seven on-orbit Tracking and Data Relay Satellites (TDRSs) located in geosynchronous orbit.  The spacecraft constellation is distributed to provide global coverage. The TDRS constellation  of spacecraft to provide  ready backup in the event of a failure to an operational spacecraft and in  specialized cases, resources for target of opportunity activities or dedicated operations.

The TDRSS ground segment is located near Las Cruces, New Mexico and consists of two functionally identical ground terminals  collectively known as the White Sands Complex. Customer forward data is uplinked from the ground segment to the TDRS and from the TDRS to the customer spacecraft. Return data is downlinked from the customer spacecraft via the TDRS to the ground segment and then on to the customer designated data collection location.

TDRSS Customers

All of the following customers rely on TDRSS to deliver command data to a payload and deliver telemetry data to scientists and operations personnel. The scientists collect and analyze experiment and sensor data, and operations personnel use satellite engineering data to manage the satellite itself.

Data relayed through TDRS has been critical to scientists investigating both near and deep space phenomena and earth science. Some of the more significant accomplishments the many customers include confirmation of the constant background radiation leftover from the "big bang" (COBE), multi-band observation of the Shoemaker-Levy comet impact on Jupiter (HST) and exhaustive imaging of the Earth which has been used for agricultural, industrial and other purposes (LSAT).

ATLAS IIA
This vehicle is currently the most powerful version of the original NASA Atlas/Centaur. In the 1960's, the Lewis Research Center managed the development of this highly successful rocket. This began Lewis' management responsibility for intermediate and large unmanned launch vehicles which it still retains. Lewis also had management responsibility for the Agena, an upper-stage booster used to launch planetary probes. In all Lewis has managed over 100 unmanned launches.
 

ATV: the most powerful space tug ever built
The Apollo spacecraft was developed and flown in the mid-sixties to bring a three-member crew to explore the Moon. The ATV, which will fly approximately 35 years later, has been designed and built to be used as a cargo re-supply ship, able to carry 7.5 tons of dry cargo and fluids to the International Space Station (ISS).  Although the concept of a space tug or transfer vehicle for moving astronauts and equipment to different Earth orbits has been envisioned for decades by different space agencies, the European built ATV will be the most powerful space tug ever built. If required in future programs, the ATV could also evolve to be used as a transfer vehicle carrying tons of supplies to the Moon orbit and beyond.
           
AURA
Earth Observing System (EOS) Aura is a NASA mission to study the Earth's
ozone, air quality and climate. This mission is designed exclusively to conduct research on the composition, chemistry and dynamics of the Earth's upper and lower atmosphere employing multiple instruments on a single satellite. EOS Aura is the third in a series of major Earth observing satellites to study the environment and climate change and is part of NASA's Earth Science Enterprise.
 
EOS - EO-1
Earth Observing-1 (EO-1) is the first satellite in NASA's New Millennium Program Earth Observing series. The EO missions will develop and validate instruments and technologies for space-based Earth observations with unique spatial, spectral and temporal characteristics not previously available. EO-1's primary focus is to develop and test a set of advanced technology land imaging instruments. However, many other key instruments and technologies are part of the mission and will have wide ranging applications to future land imaging missions in particular and future satellites in general.
 
ERBS
The Earth Radiation Budget Satellite (ERBS) is the mid-inclination satellite of the Earth Radiation Budget Experiment Research Program, and was deployed by the NASA Space Shuttle Orbiter on October 5,1984. Its current orbit is 577 x 598 km x 57 degrees inclination.
 

FUSE
For hundreds of years astronomers observed the Universe using only the visible light our eyes can see. However, visible light is a tiny portion of a much broader range of light energy known as the electromagnetic spectrum, which includes everything from energetic X-rays and gamma rays to infrared radiation and radio waves. Much of this "invisible" light gets blocked by the Earth's atmosphere, but in the last forty years astronomers have been using telescopes above the atmosphere to obtain entirely different perspectives on the Universe. A new perspective, one that has only been glimpsed a few times before, is being provided by a telescope known as the Far Ultraviolet Spectroscopic Explorer, or FUSE. Funded by NASA as part of its Origins program, FUSE was launched into orbit aboard a Delta II rocket on June 24, 1999 for at least three years of operations.
 
Gravity Probe B (GPB)
Gravity Probe B will test two extraordinary, unverified predictions of Albert Einstein's general theory of relativity. It will measure how space and time are warped by the presence of the Earth, and, more profoundly, how the Earth's rotation drags space-time around with it. These effects, though small for the Earth, have far-reaching implications for the nature of matter and the structure of the Universe. (Launched 2004 April 20)
 
Hubble Space Telescope (HST)
The Hubble Space Telescope is an operational program that continues to generate major scientific discoveries. Meanwhile, new science instruments are being developed and will be delivered and installed on-orbit via the space shuttle in 2000 and 2003. HST's instruments provide scientific data in the ultraviolet, visible, and near infrared regions of the electromagnetic spectrum. (Launched 1990 April 24)
 
International Space Station (ISS)
The International Space Station is the largest and most complex international scientific project in history. And when it is complete just after the turn of the century, the station will represent a move of unprecedented scale off the home planet. Led by the United States, the International Space Station draws upon the scientific and technological resources of 16 nations: Canada, Japan, Russia, 11 nations of the European Space Agency and Brazil.
 
LANDSAT 7
The Landsat Program is the longest running enterprise for acquiring images of the Earth from space. The first Landsat satellite launched in 1972.  The next in the series, Landsat7, launched April 15, 1999 aboard a Delta II rocket from Vandenberg Air Force Base, Calif.
 
MAP
The Microwave Anisotropy Probe spacecraft, or MAP, is making the first ever detailed map of our early universe. Recording temperature fluctuations of the Cosmic Microwave Background radiation with much higher resolution, sensitivity and accuracy than COBE, the new information contained in these finer fluctuations will shed light on several current key questions in cosmology.  MAP launched June 30, 2001 aboard a Delta-II rocket.
 
McMurdo
McMurdo Station, located at 77 degrees 51 minutes S, 166 degrees 40 minutes E, is the largest Antarctic station. McMurdo is built on the bare volcanic rock of Hut Point Peninsula on Ross Island, the solid ground farthest south that is accessible by ship. The station was established in December 1955. It is the logistics hub of the U.S. Antarctic Program, with a harbor, landing strips on sea ice and shelf ice, and a helicopter pad. Its 85 or so buildings range in size from a small radio shack to large, three-story structures. Repair facilities, dormitories, administrative buildings, a firehouse, power plant, water distillation plant, wharf, stores, clubs, warehouses, and the first class Crary Lab are linked by above-ground water, sewer, telephone, and power lines.
 

Sea Launch
Sea Launch Company, LLC, is an international partnership of American, Russian, Ukrainian and Norwegian businesses that provides a reliable, cost effective, heavy lift launch service for commercial customers. Building on proven performance and flight-tested hardware, Sea Launch offers superior value, high performance and fully integrated launch services. The Sea Launch equatorial launch site provides the most direct route to geostationary orbit, offering maximum lift capacity for increased payload mass or extended spacecraft life. At the launch site, the Launch Platform is positioned at 154 degrees West Longitude. With the Platform ballasted to its launch depth, the rocket is rolled out of its environmentally protected hangar and automatically erected on the launch pad. At L-27 hours, propellant chill-down begins at about L-4 hours, with loading at L-2.5 hours. The transporter/erector arm is lowered at L-17 minutes, signaling all parameters are "go" for launch.
 
Space Shuttle
The Space Shuttle fleet is housed and processed at NASA's Kennedy Space Center (KSC), Fla.  Next Shuttle Flight, no earlier than March 2005.
 

South Pole TDRSS Relay (SPTR)
The South Pole TDRSS Relay (SPTR) is a system which uses the NASA Tracking and Data Relay Satellite System (TDRSS) to provide data services to the South Pole.

 
 

TERRA (formally "EOS AM")
The flagship of NASA's Earth Observing System, Terra is providing scientists with global data regarding the state of the Earth's atmosphere, land and oceans, as well as their interactions with solar radiation and with each other.
 
Topex/Poseidon
 A joint effort between NASA and France's National Center for Space Studies, this satellite mission measures sea level every 10 days. This mission allows scientists to chart the height of the seas across ocean basins with an accuracy of less than 10 centimeters (4 inches), affording a unique view of ocean phenomena such as El Niño and La Niña. Launch: August 10, 1992
 

TIMED
Launched December 7, 2001 aboard a Delta II rocket from Vandenberg Air Force Base, Calif., the Thermosphere, Ionosphere, Mesosphere, Energetics and Dynamics (TIMED) mission is studying a mysterious region of our atmosphere located about 40 to 110 miles above the Earth. Known as the Mesopshere, Lower Thermosphere/Ionosphere, or MLTI, air pressure here is a thousand to a trillion times less than at sea level.
 

TRMM
The Tropical Rainfall Measuring Mission (TRMM) is a joint project between the United States and Japan, that measures tropical and subtropical rainfall through microwave and visible infrared sensors, including the first space borne rain radar. The mission is making major contributions to several international Earth Science Programs and is an integral component of NASA's long-range plan to study global change from space. Goddard designed, built and tested the observatory 'in house' at its Greenbelt, Md. facility, and also provides the science data processing system. TRMM was launched November 27, 1997 aboard a Japanese rocket. 
 

UARS
The Upper Atmosphere Research Satellite (UARS) is improving our understanding of the upper atmosphere, determining the methods needed to maintain its physical and chemical integrity, and developing techniques for early detection of harmful changes in the ozone layer. Launched September 15, 1991, from the Space Shuttle Discover, UARS had a design life of 18 months. It continues today to collect critical Earth science data.
 
RXTE
The Rossi X-ray Timing Explorer (RXTE) launched aboard a Delta II rocket December 30, 1995 from Cape Canaveral Air Force Station, Fla. into a low Earth orbit at an altitude of 362 miles (580 km) and an inclination of 23 degrees. RXTE has three instruments studying the variable X-ray sky: the Proportional Counter Array, the High Energy X-ray Timing Experiment and the All Sky Monitor. RXTE gathers data about X-ray-emitting objects within the Milky Way and beyond and performs timing studies of X-ray sources, which vary in the intensity of their emissions, and spectral studies. NASA's Goddard Space Flight Center manages the project.

TDRSS Availability

TDRSS operational availability exceeds 99%

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