Aging Satellites Could Weaken GPS SignalJuly 10, 2009

 

satellities

The Global Positioning System (GPS), whose uses range from providing personal driving directions to aiding critical military missions requiring precision bombing capabilities, could see its signal fade as early as next year when the required satellites stop functioning, according to a Government Accountability Office report.

The U.S. Air Force controls 30 satellites used for GPS, but many of them are aging and will begin to fail next year. At least 24 satellites must be fully operational for complete coverage, according to an article in the Stars and Stripes. The GAO report blames the Air Force for not replacing the aging GPS satellites in a timely way, specifically citing the delay in the development of an advanced satellite system contracted to Boeing in 1996. The Boeing-built IIF satellite is scheduled to launch toward the end of 2009, nearly three years behind schedule.

The GAO found that, according to the current satellite reliability and launch schedule estimates, there's a 5% chance that fewer than 24 satellites will be fully operational by 2010, the Stars and Stripes article notes.

As the satellites begin to fail, the military could see "a decrease of precision-guided munitions that rely on GPS to strike their targets," GAO investigators reported. "Disruption in service could require military forces to use larger munitions or to use more munitions on the same target to achieve the same level of success." If the number of working satellites falls below 24, commercial and military users will see a noticeable decline in the quality of the coverage, according to the article.

In response to the GAO report, the Air Force Command said it realized the "potential for an availability gap" years ago and is working to remedy the problem.

GPS went online in 1995 but had been in development since the 1970s. Some satellites have been replaced or upgraded over that period.