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Atlas rocket puts up NASA communications spacecraft

Posted: January 23, 2014

A United Launch Alliance Atlas 5 rocket topped with a NASA science-relay satellite sped into space Thursday night, lighting up Florida's Space Coast with a raucous liftoff show.

The TDRS L spacecraft streaks to orbit. Credit: Walter Scriptunas II / Scriptunas Images
Weighing 746,061-pounds and standing 40 feet taller than the Statue of Liberty, the two-stage rocket launched from Cape Canaveral's Complex 41 at 9:33 p.m. EST. It was the 10th straight Atlas to launch on the first attempt.

The liftoff marked the 625th rocket with the name Atlas and the 43rd for the Atlas 5 family.

About two hours later, the Centaur upper stag deployed the Tracking and Data Relay Satellite L, or TDRS L, into geosynchronous transfer orbit as prescribed.

"This spacecraft is part of a NASA-wide initiative to replenish the Space Network constellation that has been on-orbit since the early 80s" said Paul Buchanan, TDRS deputy project manager.

Created in 1973 and launching its first satellite in 1983, the system was conceived to provide constant communications with astronauts and science spacecraft circling the planet in low-Earth orbit. The TDRS design uses a constellation of geosynchronous satellites parked 22,300 miles above Earth to provide global coverage.

"The TDRS constellation is a critical national asset, not only when we supported the space shuttle for all those years it was flying. Now it's the International Space Station and Hubble. A lot of the missions -- the late 80s to now -- the amount of communications bandwidth or user load and request for all the science data, the amount of users of TDRS has gone up just because of the number of satellites that have gone up," said Buchanan.

Looking down from that vantage point, the TDRS network receives signals from vehicles like the space station flying at a mere 250 miles and routes the telemetry, voice, video and science information to a dedicated ground terminal for delivery to Houston.

No matter where the space station is located at any given moment, TDRS has the outpost in sight for the two-way communications.

What's more, the dazzling views of the cosmos captured by the Hubble Space Telescope are relayed through TDRS, as are the measurements obtained by NASA's fleet of Earth-watching environmental satellites and astronomy birds peering into the universe. There's even telemetry-relay from ascending rockets that beam through the network, including the Atlas-Centaur vehicle carrying TDRS K.

Despite retirement of the space shuttle orbiters, the demand for TDRS services has not waned. Just the contrary, project officials say, as the space agency sends up more and more science satellites that need their communications relayed.

"The communications services provide is a tri-band -- Ku, Ka and S-band -- and the throughput is higher due to the state of electronics and technology growth. That's why NASA decided to replenish the constellation," said Buchanan.

And with the shuttles no longer around to deliver supplies to the space station, international cargo ships like Europe's ATV and Japan's HTV freighters and commercial craft like the SpaceX Dragon and the Orbital Sciences Cygnus route their telemetry through TDRS.

The first generation of TDRS spacecraft, built by TRW as the system's A through G satellites, launched aboard 7 space shuttle missions between 1983 and 1995. One, however, was lost aboard Challenger in 1986.

Four of the six that went into operation remain alive today, well outlasting their 10-year design life.

A second generation, a batch of three made by Boeing and known as TDRS H, I and J, flew aboard Atlas 2A rockets between 2000 and 2002 to improve the capabilities of the system.

Now, Boeing is providing three more to replenish the constellation and keep it viable into the 2020s. TDRS K was launched last January and TDRS L will be followed by TDRS M no sooner than 2016.

"The legacy constellation plus K, L and M will provide near continuous communications services to 2022-2023," Buchanan said.

"TDRS K is performing flawlessly. It's doing great. We expect the same from TDRS L."

The satellite stood 26 feet tall and weighed over 7,600 pounds at launch, including 3,700 pounds of maneuvering fuel loaded inside the craft. Once fully deployed in space, TDRS L's solar wings will stretch 69 feet tip-to-tip to generate 3,220 watts of power and charge internal nickel-hydrogen batteries.

The primary physical feature of the satellite is two 15-foot-diameter flexible graphite mesh antenna dishes that were folded like taco shells for launch, then springing into shape once released in orbit.

The antennas offer gimbal tracking of targeted spacecraft flying beneath the satellite, providing high-gain communications to the station, Hubble and other craft for vital contacts and data dumps.

After finishing the orbit-raising activities two weeks following the launch, the spacecraft's full appendages will be deployed, starting with one solar array, then the booms holding the Single Access antennas fold out, the other solar wing extends, the forward Omni swings into place and the space-to-ground antenna is positioned.

The spacecraft will undergo testing at 150 degrees West, then drift eastward to its operational location at 49 degrees West.

The launch was the first of 9 planned for the Atlas 5 rocket in 2014, including 6 from Cape Canaveral and three from Vandenberg Air Force Base in California. Next up is the March 25 launch of the NROL-67 mission for the National Reconnaissance Office from the Cape.