T-Sat Demise Poses Bandwidth Challenge

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  Space News Business

T-Sat Demise Poses Bandwidth Challenge

By TURNER BRINTON
Space News Staff Writer
posted: 21 April 2009
01:58 pm ET





WASHINGTON — The U.S. Defense Department’s decision to cancel the $26 billion Transformational Satellite (T-Sat) communications system raises questions about how it will meet the military’s skyrocketing requirement for secure communications links, particularly for mobile forces.

In announcing the decision April 6, Defense Secretary Robert Gates said the Pentagon will instead procure more of the previous-generation Advanced Extremely High Frequency (AEHF) satellites from prime contractor Lockheed Martin Space Systems of Sunnyvale, Calif. The Air Force has also indicated it will procure more Wideband Global Satcom (WGS) craft from Boeing Space and Intelligence Systems of Seal Beach, Calif.

Officials from both companies touted the upgrade potential of their respective systems. But Air Force Col. James Wolf, Air Force Space Command’s military satellite communications lead, said the upgrade strategy would still leave the military well short of the bandwidth that even the scaled back version of T-Sat – T-Sat Block 10 – would have delivered.

“Moving to T-Sat Block 10 was a decision to let some requirements go unfunded for some time,” Wolf said in a recent interview. “It was clearly a decision to defer communications-on-the-move satisfaction and would have met significantly less of the airborne [intelligence, surveillance and reconnaissance] support requirement. It’s hard for me to see how [AEHF and WGS] could be spiraled to even the T-Sat block 10 capability, and that was just the first increment.”

Possible alternatives to T-Sat had been studied many times, but no other architecture would fulfill the military’s requirement as economically, Wolf said. The latest such study resulted in the decision late last year to eliminate some of the advanced capabilities originally envisioned for T-Sat.

To date, the Air Force has spent some $1.5 billion on competing T-Sat design studies led by Boeing and Lockheed Martin, who were awarded $75 million contracts late last year to continue working on the program. The Air Force completed April 10 its planned interim design review of Lockheed Martin’s work, said Rick Skinner, the company’s vice president of strategic planning for global communications systems. The service is expected to do the same review of Boeing’s work on April 13, Boeing spokesman Lewis Brinson said.

Meanwhile, Air Force Space Command initiated the expansion of the AEHF constellation with the April 8 posting of a sources sought notice for satellites four and five, which will be clones of the first three.

Because of the production gap between the third and fourth AEHF satellites, the unit cost jumped from $939 million for the third satellite to an estimated $2.6 billion for the fourth, according to a September 2008 Pentagon acquisition cost summary. Skinner said the Air Force’s best bet for realizing economies of scale on the program is to purchase both the fourth and fifth satellites in 2010.

With five AEHF satellites of the current design on orbit, the amount of protected bandwidth will be around 1 gigabit per second, Skinner said. The T-Sat constellation, by contrast, was originally expected to deliver 11 gigabits per second; the scaled back version was to deliver around 5 gigabits per second.

Skinner said that in theory, each AEHF platform’s bandwidth capacity could be scaled up from the current 200 megabits per second to 2 gigabits per second. The upgrade potential is less if the Air Force chooses not to scale up in size, but Skinner said it still would be possible to wring more bandwidth out of the platforms by moving to more efficient electronics and batteries.

“A lot of the technology matured under T-Sat could be rolled into future AEHF satellites for users who need communications-on-the-move capabilities and network functions associated with Internet protocol routing,” Skinner said. “It just depends on how much the government values those services. If AEHF is moved to a heavy-launch Delta 4 rocket, or are larger version of the medium launch vehicle, that would allow us to improve the capability.”

Skinner said Lockheed Martin has proposed one AEHF upgrade program that would deliver 80 percent of the bandwidth T-Sat Block 10 was expected to provide. “It includes communications-on-the-move with still a very high data rate to 1-foot (0.3 meter) terminals moving around the battlefield. It would have Internet protocol routing as T-Sat Block 10 would have, but with fewer channels.”

Boeing also believes the WGS constellation could be upgraded with some of the communications-on-the-move antennas, Internet protocol routing technology and the satellite-to-satellite laser links that were part of the original T-Sat design, Jim Simpson, Boeing’s vice president of business development, said in an e-mailed response to questions.

“We have looked at it and it is feasible,” Simpson said. “Clearly Boeing is ready, willing and able to further increase the capabilities of our WGS satellites, and we have been in discussions with senior government officials about the possibilities.”