Maybe this is a little off topic, but this goes for any of you FE'ers who disbelieves that GPS does use satellites. Have you read the recent news? the Solar Burst may threaten GPS.
"The cause for their concern, Johnson said, was an unexpected solar radio burst on December 6 that affected virtually every GPS receiver on the lighted half of Earth. Some receivers had a reduction in accuracy while others completely lost the ability to determine position, he said."
"Solar activity rises and falls in 11-year cycles, with the next peak expected in 2011."
"If that increasing level of activity produces more such radio bursts the GPS system could be seriously affected, the researchers said."