WASHINGTON — As the U.S. House of Representatives was approving legislation this week limiting year 2000 liability suits against high-tech companies, the House Science Committee was quizzing government agencies charged with ensuring that the nation's navigation and other satellites are prepared for the millennium as well as an August rollover of critical satellite timing devices.
Of particular concern is the timing mechanism for global-positioning-system (GPS) satellites that guide weapons to targets and fishermen to their catch. Along with its locator function, GPS provides critical timing information that it used in communications and other networks to synchronize transmission of packets of voice, data and video.
"Timing errors due to the lack of synchronization, in fact, can lead to data loss and degradation and eventually network disruption or even complete failures," Keith Rhodes, a technical director with the congressional General Accounting Office, told lawmakers.
"The satellites won't fall out of the sky," Rhodes added. "The problem is on the receiving end."
Concern over the rollover problem focuses specifically on Aug. 21, when GPS timers roll over and reset at zero. While the timers are not tied to the calendar and are thus largely immune to the Y2K bug, the ground stations that control GPS, weather and other satellites remain vulnerable to software glitches.
The so-called GPS "end of week" rollover occurs every 20 years because GPS system time is counted in weeks beginning in January 1980. At midnight between Aug. 21 and 22 the GPS timing system will roll over from 1,023 to zero. "This could be interpreted as an invalid date in GPS receivers that were not designed to meet GPS specifications," said Lee Holcomb, NASA's chief information officer.
Defense officials charged with ensuring U.S. satellites can endure the rollover problem and the millennium bug told lawmakers they must still complete end-to-end testing of the 28-satellite GPS constellation. Still, Marvin Langston, the Pentagon's deputy chief information officer, said he foresaw no "show stoppers" that would disrupt the GPS navigation or timing capabilities.
Langston said GPS satellites are Y2K- and rollover-compliant but "some mission-essential support systems that provide real-time telemetry monitoring are still in the process of achieving Y2K compliance."
U.S. Space Command recently completed the first phase of GPS operational testing for Y2K and rollover compliance. Results are expected as early as next week. Another set of operational tests is scheduled to begin in late May.
NASA's Holcomb said the end-to-end testing of satellites and spacecraft ranging from the International Space Station to the plutonium-powered Cassini space probe of Saturn will be completed by the end of June. A separate launch-pad test of Space Shuttle systems is planned for August, Holcomb said.
Together, NASA must ensure that the 38 satellites it manages are tested for Y2K and rollover compliance. NASA has spent about $47 million to fix software code affected by the Y2K bug. Department of Defense Y2K spending totals about $3.7 billion. Initial government estimates of the overall cost of ensuring Y2K compliance were about $2.3 billion.
