Satellite navigation works best with 24 functioning orbiters. If several were to switch off, thousands of adventurers could go off course.
How it Could Happen
According to a recent analysis by the Government Accountability Office, there’s a 20 percent chance of a GPS meltdown by 2010, due to cost overruns, old satellites, and limited replacements. But the Department of Defense, which maintains the GPS system, has denied any serious problems—and most experts agree. “I think that the GAO is taking a somewhat pessimistic view of satellite lifetimes,” says Mark Psiaki, Ph.D., a professor at Cornell’s Global Positioning System Laboratory. “What the GAO calls a ‘blackout’ may not actually translate into a serious problem for any given user.”


Adventure Ratings
Gear Reviews
National Parks
Reader Photo Contest
100 Best Books
Photo Galleries
Video