Service also plans satellite control standards

The Air Force is upgrading its satellite ground stations for digital signal processing, using interface specifications it hopes other agencies will adopt to spur federal satellite interoperability.

Over the next decade, Air Force tracking stations will be outfitted with commercial IP networking equipment, said Col. Michael Coolidge, a deputy systems program director at the Satellite and Launch Control Systems Program Office at Los Angeles Air Force Base, Calif.

The Air Force hopes other Defense, intelligence and civilian agencies 'will begin to procure their systems to these new specifications, guaranteeing interoperability,' Coolidge said.

The Air Force operates more satellites than any other agency. Its satellite control network provides ground support for more than 100 Air Force and other federal satellites. There are two control nodes in Colorado and California, plus tracking and control antennas at many locations around the globe.

Interoperability would mean any government satellite could be controlled from its operations center, through any of the government's space antenna systems or remote tracking stations, according to a paper by Carl Sunshine, a systems engineer at Aerospace Corp. of El Segundo, Calif., which is supporting the project.

Coolidge said he expects the Air Force to turn to IP communications to cut costs. Until the late 1990s, it used circuit-switched, long-haul communications services. That changed to asynchronous transfer mode, which can carry IP traffic but is costlier.

'The move to packet-based protocols and packet-switched networks has been an implicit goal and a major technical driver,' Coolidge said.

Much more work will be needed, however, to bring older satellites into line. Civilian and DOD satellite operations have different encryption requirements for telemetry and commands.

'Some missions need to accurately preserve command and telemetry timing between remote ground stations and the satellite operations center,' Coolidge said. Security and timing over shared packet networks are more difficult than with dedicated circuit services, he said.

Upgrading the satellites could prove even more difficult. Besides the numerous spacecraft now aloft, many planned for launch do not have packet-based networking capability.

So, another part of the project is to 'deal with the legacy in space today,' said John Pietras of Global Science and Technology Inc. of Greenbelt, Md., speaking at NASA's recent Space Internet Workshop.

'You can't just arbitrarily assume you have IP on the spacecraft,' Pietras said. 'We have ground systems that are expecting to connect with analog circuit-switched networks.'

About the Author

Joab Jackson is the senior technology editor for Government Computer News.

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