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Forum:Satellites - Robotic Probes
Topic:Tracking and Data Relay Satellite-L (TDRS-L)
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The constellation of satellites orbiting Earth at 22,300 miles revolutionized communications for the nation's space agency by allowing nearly continuous transmission of information during a mission. Before the TDRS network was established, NASA relied on a patchwork of ground stations based around the world to stitch together coverage zones. Astronauts and Earth-orbiting scientific spacecraft would relay messages only when they passed over or near one of the ground stations.

Working in conjunction with the other TDRS satellites, TDRS-L will convey signals, information and commands from ground controllers to the International Space Station and NASA's diverse assortment of scientific satellites including the Hubble Space Telescope.

"The TDRS constellation brings back all of the data and video that we see every day from the International Space Station," said Tim Dunn, NASA launch director. "TDRS also supports all of the data from the Hubble Space Telescope and all of our low Earth orbit NASA science missions."

The latest TDRS spacecraft is identical to one launched a year ago, TDRS-K. Both are the third generation of TDRS spacecraft and are part of a replenishment program for NASA's Space Network overseen at the agency's Goddard Spaceflight Center in Maryland.

The satellite arrived at Kennedy's Shuttle Landing Facility inside an Air Force C-17 transport aircraft from its manufacturing plant in California. It was taken to the Astrotech payload processing facility in Titusville for numerous tests and was packed inside the two-piece payload fairing that will protect it during the climb into space.

"This one was pretty much fully assembled and ready to go," said Diana Calero, NASA mission manager. "There were tests done since they wanted to make sure nothing happened on the shipment over from Los Angeles."

The processing was aided by the fact that previous TDRS spacecraft had been put through the same regimen.

"Everything's been going very smoothly with this because we had had the experience of TDRS-K so this has very smooth," said Brett Perkins, launch site integration manager at Astrotech. "It's fun when everything goes right and so far the flow has gone really smoothly. The fact that nothing has gone wrong with this flow took a lot of the stress out of it."

The TDRS-L will ride into space on an Atlas V booster and Centaur upper stage, a combination that has become a workhorse for the agency's recent missions. The Centaur, which takes over after the Atlas V booster's stage has exhausted its fuel, will place the TDRS on a path to reach its 22,300-mile orbit.

The launch will come about 50 years after the first successful launch of a Centaur rocket. The stage was the first to use liquid hydrogen as a fuel in order to get higher performance. Working at Glenn Research Center in Ohio, engineers wrestled with the design of the stage and its RL-10 engine for several years before it worked right and they continued to modify and perfect the engine and its stage steadily over the years.

It helped launch NASA's Surveyor spacecraft to land on the moon ahead of the Apollo astronauts in the 1960s and '70s.

Thirty-feet-long and 10-feet in diameter and with two engines, the original Centaur has given way to a stretched version that is 41-feet-long with a single RL-10A engine producing more than 22,000 pounds of thrust. The stage also is being redesigned for possible use on spacecraft carrying humans into orbit.

For the TDRS-L spacecraft and the launch teams of NASA's Launch Services Program and United Launch Alliance, launch day begins several hours before liftoff. They will fuel the two stages of the rocket remotely and follow a careful slate of tests and performance checks leading up to the launch.

"The last four minutes when you're going into terminal count, you don't have a whole lot of time, you don't have time to stop and start doing things and troubleshooting," Calero said. "Everyone's staring at their data, your ear's tuned to see if you hear anything and right as you go down to the final countdown and it lifts off, OK, now you made it through the count, that's great. Then you're listening to everything as it's going up to make sure everything is nominal."

It will take only a few minutes for the Atlas V to lift the TDRS-L clear of the lower atmosphere. After the Centaur's first burn ends, it and TDRS-L will orbit Earth for more than an hour before the Centaur reignites to put the TDRS into what's known as a geosynchronous transfer orbit. That means the spacecraft will follow a path out to 22,300 miles and then back to only a couple hundred miles and use its own thrusters to gradually make the orbit circular at the high altitude.

It will take about a month to check out all the systems on the communications satellite vast platform and then it will be formally handed over to NASA for use in the network.

Robert PearlmanUnited Launch Alliance (ULA) release
United Launch Alliance Successfully Launches NASA's Tracking and Data Relay Satellite payload

A United Launch Alliance (ULA) Atlas V rocket successfully launched NASA's Tracking and Data Relay Satellite (TDRS-L) payload at 9:33 p.m. EST today from Space Launch Complex-41. This was the first of 15 ULA launches scheduled for 2014 and the 78th ULA launch for ULA in just over seven years.

"ULA and our mission partners are honored to work with the outstanding NASA team and we are proud of the vitally important data relay capabilities that were safely delivered today," said Jim Sponnick, ULA vice president, Atlas and Delta Programs. "With 43 successful missions spanning a decade of operational service and launched with a one-launch-at-a-time focus on mission success, the Atlas V continues to provide reliable, cost-effective launch services for our nation's most complex and valued payloads."

Credit: United Launch Alliance/Ben Cooper

This mission was launched aboard an Atlas V 401 configuration vehicle, which includes a 4-meter diameter payload fairing. The Atlas booster for this mission was powered by the RD AMROSS RD-180 engine, and the Centaur upper stage was powered by a single Aerojet Rocketdyne RL10A-4 engine.

NASA established the TDRS project in 1973, with the first launch in 1983, to provide around-the-clock and around-the-Earth communications for the network that routes voice calls, telemetry streams and television signals from the International Space Station, as well as telemetry and science data from the Hubble Space Telescope and other orbiting spacecraft.

"Atlas and TDRS have supported each other for almost 20 years, and all three of the second generation satellites, now known as TDRS 8, 9, and 10, launched on Atlas vehicles in 2000 and 2002," said Sponnick. "While we were integrating those spacecraft onto Atlas in the late 1990s, we also developed a new TDRS-compatible transmitter so that Atlas could use the TDRS constellation to receive and distribute the launch vehicle telemetry relay during flight. We are now also using TDRS services for our Delta II and Delta IV programs."

ULA's next launch is the Delta IV GPS IIF-5 mission for the Air Force planned for Feb. 20, 2014, from Space Launch Complex-37 at Cape Canaveral Air Force Station, Fla.

United Launch Alliance program management, engineering, test, and mission support functions are headquartered in Denver, Colo. Manufacturing, assembly and integration operations are located at Decatur, Ala., and Harlingen, Texas. Launch operations are located at Cape Canaveral AFS, Fla., and Vandenberg AFB, Calif.

Robert PearlmanThe Boeing Company release
Boeing TDRS-L Relay Satellite Sends 1st Signals from Space

Boeing has received the first on-orbit signals from the Tracking and Data Relay Satellite (TDRS)-L after a successful launch today, bolstering the tracking and communications network used by NASA and its customers.

TDRS-L is the fifth Boeing-built satellite to join the network that NASA uses in support of vital missions, including the International Space Station, studying Earth's changing climate and looking into deep space with the Hubble Telescope. TDRS satellites relay signals to and from Earth and the International Space Station and other space assets.

"This advanced satellite is an important part of NASA's critical communications relay network and will improve capacity and enhance bandwidth at the lowest cost," said Craig Cooning, vice president and general manager of Boeing Space & Intelligence Systems.

The satellite launched on a United Launch Alliance Atlas V vehicle today at 9:33 p.m. Eastern time from Cape Canaveral Air Force Station, Fla. Controllers at the Boeing Mission Control Center confirmed initial contact with it one hours and 54 minutes later. After reaching final orbit, TDRS-L will undergo approximately three months of tests and calibration before its handover to NASA.

TDRS-L joins four other Boeing TDRS satellites in NASA's network. It is the second of three advanced versions of the satellites, with the third – TDRS-M – ready for launch in 2015.

Boeing has been providing vital space communication services to NASA for more than four decades.

Robert PearlmanNASA release
NASA Launches Third Generation Communications Satellite

NASA's Tracking and Data Relay Satellite L (TDRS-L), the 12th spacecraft in the agency's TDRS Project, is safely in orbit after launching at 9:33 p.m. EST Thursday aboard a United Launch Alliance Atlas V rocket from Cape Canaveral Air Force Station in Florida.

Ground controllers report the satellite — part of a network providing high-data-rate communications to the International Space Station, Hubble Space Telescope, launch vehicles and a host of other spacecraft — is in good health at the start of a three-month checkout by its manufacturer, Boeing Space and Intelligence Systems of El Segundo, Calif. NASA will conduct additional tests before putting TDRS-L into service.

"TDRS-L and the entire TDRS fleet provide a vital service to America's space program by supporting missions that range from Earth-observation to deep space discoveries," said NASA Administrator Charles Bolden. "TDRS also will support the first test of NASA's new deep space spacecraft, the Orion crew module, in September. This test will see Orion travel farther into space than any human spacecraft has gone in more than 40 years."

The mission of the TDRS Project, established in 1973, is to provide follow-on and replacement spacecraft to support NASA's space communications network. This network provides high data-rate communications. The TDRS-L spacecraft is identical to the TDRS-K spacecraft launched in 2013.

"This launch ensures continuity of services for the many missions that rely on the system every day," said Jeffrey Gramling, TDRS project manager at NASA's Goddard Space Flight Center, Greenbelt, Md.

The TDRS fleet began operating during the space shuttle era with the launch of TDRS-1 in 1983. Of the 11 TDRS spacecraft placed in service to date, eight still are operational. Four of the eight have exceeded their design life.

Boeing Space and Intelligence Systems completed the TDRS-L integration and testing at its satellite factory in El Segundo in November and launch processing began after the spacecraft arrived in Florida Dec. 6.

TDRS-M, the next spacecraft in this series, is on track to be ready for launch in late 2015.

NASA's Space Communications and Navigation Program, part of the Human Exploration and Operations Mission Directorate (HEOMD) at the agency's Headquarters in Washington, is responsible for the space network. The TDRS Project Office at Goddard manages the TDRS development program. Launch management of the launch service for TDRS-L is the responsibility of HEOMD's Launch Services Program based at the agency's Kennedy Space Center in Florida. United Launch Alliance provided the Atlas V rocket launch service.

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