With a GPS failure possible, is it still safe to buy?
- — 20 May, 2009 23:56
After a government watchdog agency warned that the U.S. Global Positioning System might fail, potential customers may wonder whether buying a GPS device is still a good idea. In a word: Yes.
Any GPS outage is likely to develop over a period of years and the U.S Air Force, which manages the satellite navigation system, is under pressure to speed modernization efforts.
Further, the cost of consumer GPS devices has dropped below $100 for units with turn-by-turn spoken navigation. At that price, the GPS unit can quickly pay for itself. Consumers also don't require as precise a GPS fix as military users, who are more likely to notice GPS "brownouts."
The U.S. Government Accountability Office has warned Congress that mismanagement of a $2 billion upgrade program threatens GPS service, which the government offers free to users. Older satellites start dying next year and replacements are being launched much more slowly than is necessary to maintain service, the report to Congress said.
"Based on the most recent satellite reliability and launch schedule data approved in March 2009, the estimated long-term probability of maintaining a constellation of at least 24 operational satellites falls below 95% during fiscal year 2010 and remains below 95% until the end of fiscal year 2014, at times falling to about 80%," the report stated.
Speeding the launch schedule is one solution to the problem, but the fact exists that GPS can operate with fewer than 24 satellites, though with potentially reduced precision.
It could also take longer for GPS devices to compute a location "fix" if the number of operational satellites decreases.
Fewer GPS satellites could also make it more difficult to receive a location fix in areas with a poor view of the sky, such as the downtown "canyons" of major cities. Coverage inside buildings could also suffer.
Nevertheless, two things are working in GPS's favor: One is its popularity with consumers. Second is its role in national security, making it imperative that a solution be found and raising the political pressure for doing so.
My guess is the government will find a way to fly GPS satellites more quickly and that enough will remain operational to make any degradation of service difficult for civilian users to detect.
If some banks are "too important" to fail, so are some government programs. GPS is one of those and, like the banks, it appears likely that large sums of money will be thrown at finding a solution.
Any lack of confidence in the American GPS is a boon for supporters of the European Galileo satellite navigation system, which starts rolling out later this year. Over the long term, dual GPS/Galileo devices could improve both reliability and positional accuracy.