The UK's Daily Telegraph carried a story today about the possibility that the satellites of the Global Positioning System "could begin to fail as early as next year." As is often the case with news stories, this is not a useful statement about the future – they could break down next week, or not for years, as the actual substance of the story is simply that a number of the satellites are more than four years past their design lifetime. But I digress – the interest of this story is what would happen if they do start breaking down. Increasing pressure on public finances makes it quite probable that there will be further delays in putting up replacements, even though as space systems go, this must be a major priority. Curiously, once a system like this is up and running, businesses and governments start using it as if it will simply be there forever and give little thought to what would happen if it suddenly went down for an extended period. Each individual user is taking their own usage for granted, and no one thinks about the enormous overall dependence we develop without noticing. Maybe there should be a GPS-free day once a month, to make sure the old skills and tools don't completely atrophy.