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You answered "25 minutes". Click "CONTINUE" to proceed to the next question.
Interesting fact:
GPS used to have quite a different name: Navstar. The first satellite that launched for Navstar went up all the way back in 1978, with 9 out of 10 of its satellites finally making it into orbit. But the first modern and fully formed GPS satellite was launched in 1989, and what a great tradition it kicked off!