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Atlas 5 puts science-relay satellite into orbit for NASA

Posted: January 30, 2013

Advancing from the days of ground stations providing sporadic coverage of man's early exploits in space to the creation of an orbiting satellite network for constant communications, the third generation of NASA's tracking stations in the sky roared off the launch pad Wednesday night.

Credit: Pat Corkery/United Launch Alliance
A United Launch Alliance Atlas 5 rocket, capping its quickest pre-flight processing flow to date, fired into the nighttime sky from Cape Canaveral's Complex 41 at 8:48 p.m. EST (0148 GMT).

At just 27 days from the start of stacking to main engine ignition, ULA's efforts at "span reductions" bore fruit by besting the previous quick mark by two weeks. The launch provider says the improved tempo will heighten efficiencies, increase available slots in the manifest and cut costs.

"It offers our customers added manifest flexibility to meet their schedules and it also offers additional launch opportunities to ensure payloads can be launched on time and reliably," said Vern Thorp, ULA's program manager for NASA missions.

Displaying that reliably Wednesday night on its 35th mission in a decade and the 8th for NASA, the Atlas-Centaur artfully propelled the Tracking and Data Relay Satellite K into its prescribed orbit, reaching an elliptical orbit with a high point of 22,245 statute miles, low point of 2,680 statute miles and inclination of 25.6 degrees.

Lasting an hour and 46 minutes from departing the launch pad through deployment of the payload in the geosynchronous transfer orbit, the ascent went exactly as planned to bolster NASA's in-space communications infrastructure.

"Launch is just the beginning of this satellite's journey, and the addition of TDRS K to the overall constellation will continue the successful legacy of the project and strengthen NASA's communications system that is so vital to the International Space Station and many other satellites in orbit today and will be in the future," Thorp said.

This illustration shows TDRS K separating from the Centaur upper stage. Credit: United Launch Alliance
The TDRS system was born in 1973 to keep astronauts and satellites in constant contact with mission controllers, closing the substantial gaps every orbit as spacecraft passed into and out of range of ground stations scattered around the globe.

When TDRS first became operational in late 1983, the initial space shuttle mission to use the system relayed more information to the ground during its 10 days in orbit than in all 39 previous American manned spaceflights.

Relying on dispersed ground stations was a costly requirement and subjected the sites' operators to dangerous conditions in far-off countries, yet the system provided only 15 percent communications capability per orbit.

"What would it take to have continuous 24/7 communications services for NASA missions? That is what prompted the TDRS constellation," said Paul Buchanan, TDRS deputy project manager and contracting officer.

"We didn't want to the outages of voice or data, that prompted to the TDRS system to be designed and built."

Prolonged disconnections were eliminated with the debut of TDRS, effectively moving those tracking stations 22,300 miles into the sky to gaze down at the user spacecraft, upping the blanket coverage to 85 percent per orbit with two operational TDRS satellites.

But looking to close that remaining gap, or zone of exclusion, more spacecraft were put into operation to create full 100 percent orbital coverage.

Six of the seven first-generation satellites went into orbit, with one lost in the Challenger accident. The space shuttles deployed those TRW-built craft between 1983 and 1995, with four of the long-lived birds still doing the job today 22,300 miles above Earth.

"As spacecraft age, they all kind of develop their own unique set of problems, especially for spacecraft beyond their design life. So each one has to be cared for in different ways," said Jeff Gramling, NASA's TDRS project manager from the Goddard Space Flight Center.

But despite their advanced ages, they remain useful, and the demands of communications services continue to grow.

"We've been fortunate in that our first-generation spacecraft, the one of those we launched through 1995 with a 10-year design life, have lived well beyond the design life. That has given us the time to make sure are able to repopulate or recapitalize the network," said Gramling.

Liftoff of TDRS K. Credit: Pat Corkery/United Launch Alliance
A second-generation came along between 2000 and 2002, as the TDRS H, I and J satellites were deployed by unmanned Atlas 2A rockets from Cape Canaveral to improve the capabilities of the network.

Now, Boeing is building the K, L and M spacecraft for launches over the next three years to keep the system replenished and operating well into the 2020s.

"What we are doing is ensuring that we can continue provide services that they've come to rely on -- persistant, continuous coverage with no latiency to facilitate their missions," Gramling said.

"Lots of people out there are relying on the system and we need to make sure we keep it healthy to satisfy their needs."

TDRS L should be ready to fly next January and M will follow in December 2015.

"Architecturally they are the same as HIJ with a little better performance," Gramling said. "From a users' perspective, its generally continuing to provide the same services we provided in the past."

This first of the third-generation, known as the Tracking and Data Relay Satellite K, or TDRS K, is headed for service 22,300 miles over the Pacific Ocean.

"TDRS K bolsters our network of satellites that provides essential communications to support space exploration," said Badri Younes, deputy associate administrator for Space Communications and Navigation at NASA Headquarters. "It will improve the overall health and longevity of our system."

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 K'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 are folded like taco shells for launch, then spring into shape once released in orbit. They 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.

S-band, Ka-band and Ku-band are the frequencies supported through the TDRS network.

An artist's concept of TDRS K in orbit. Credit: NASA
"The voice and data communications the TDRS constellation brings back to Earth every day from the International Space Station, the Hubble Space Telescope and many of our NASA science spacecraft -- it touches each of our lives," said Tim Dunn, the NASA launch director for TDRS K.

Boeing designed, developed and tested the spacecraft in El Segundo, Calif., and NASA provided the launch. Once the aerospace company gets the satellite into the proper orbit, deploys the appendages and demonstrates that the craft works, the space agency then takes ownership for a lifespan of 15 years or more.

"We are launching now for an immediate need and replenishment schedule, we're also expecting some of the other legacy spacecraft from the TRW days to decommissioned in the next years. That's reason for not just K but L and M. It's a fine balance between the existing system, and when they fail, versus the replenishment," Buchanan said.

The three satellites of the third-generation, the Atlas 5 rockets to launch them and some work performed on the ground systems amount to a $1.1 billion program.

"All the Hubble pictures come through TDRS, all the video that we see from the space station and the astronauts and the video we saw from the shuttle, it all comes through TDRS, and then we have all the Earth-orbiting satellites, all that data comes through TDRS," Buchanan said.

"The government has designated TDRS as a critical national asset due to the fact that continuous communications around the world is critical to people's security, weather-related events, that's the important value NASA provides."

Wednesday's launch was the 35th flight for the Atlas 5 since debuting in 2002 and the 30th to occur from the Florida spaceport. Next up is deployment of an advanced Landsat spacecraft for NASA and the U.S. Geological Survey on Feb. 11 from Vandenberg Air Force Base in California.

The next Atlas launch from Cape Canaveral is planned for mid-March carrying the Air Force's second Space Based Infrared System Geosynchronous satellite, or SBIRS GEO 2, for missile early-warning detection.