DOD scales back GPS feature

Citing security reasons, the U.S. Space Command this month stopped issuing important supplemental data on its Global Positioning System satellites that until now has assited civil users in tracking the systems and planning observations.

The move comes only weeks before the U.S. began bombing operations in Kosovo and raises questions about how the military plans to share GPS access in the future.

According to Richard Langley, a professor of geodesy and precision navigation at the University of New Brunswick, Canada, Spacecom on March 5 stopped issuing so-called two-line orbital element sets for its satellites to civil users because the data is now considered too "sensitive" for public issue. However, the satellite signals have not been shut down, he said.

"The information on the GPS satellites has always been freely available via NASA's Goddard Space Flight Center, [at least] until a few weeks ago," Langley said. "The withdrawal of these two-line elements means that these users will have to find alternate [methods] of checking on the satellites," he said.

A spokesman for Spacecom said the changes are transparent to most GPS users around the world. "All we've done is make it more difficult for individuals to know where our national defense [satellite] assets are," he said. The spokesman conceded that there is a small user community concerned with locating the satellites, but, he said, "that's not who we're serving."

The Defense Department already degrades the accuracy of civil GPS signals as a means to deny terrorists and other U.S. adversaries' precision targeting capabilities. Known as selective availability, the process seeks to maintain GPS support for DOD's navigation warfare needs while denying this capability to others. However, pressure has been growing throughout the civil and commercial sectors to terminate selective availability.

Testifying last week before the Senate Armed Services Committee, Gen. Richard B. Myers, commander in chief of Spacecom, said DOD plans to discontinue Selective Availability at least by 2006. But Myers also said the Clinton Administration will revisit the issue each year beginning next year, making its decision based on recommendations from the Transportation Department and the CIA.

"We must...continue to intelligently balance the needs of DOD with the needs of the civil GPS user community," said Myers. However, "as we attempt to balance the needs of all sectors for this emerging global commodity, we [also] must ensure our military forces retain a warfighting advantage," Myers said.