That snazzy new smartphone or satnav that you've just bought might start to have problems getting a location lock by 2010, if reports are to be believed that the Global Positioning System is in trouble.
The network of 24 satellites is under the control of the US Air Force, but the country's Government Accountability Office has released a report expressing concern about the military's upkeep of the system.
According to the report, the Air Force has had problems with contractors building and launching the satellites on time, as well as a series of industry mergers that has resulted in knowledgeable workers leaving the industry.
As a result, the programme is running almost 3 years late. The report uses reliability curves for the satellites to predict that the probability of keeping a 24-satellite constellation going drops below 95% in 2010 and as low as 80% in 2012.
If the Air Force continues to fail to meet its goals for the next generation of satellites, then there's only a 10% chance of the system surviving to 2017.
Luckily, help is on the way from the Europeans, Russians and Chinese, all of whom have their own satellite navigation systems in different states of readiness.
Europe's Galileo system is due to come online in 2013 and a 2004 agreement has meant that it will be able to interoperate with GPS in the future. It's a largely civilian system, so won't be subject to the US government's military whims.
Russia's GLONASS system was launched in 1995, but almost immediately fell into disrepair after economic problems in the country. The vast country has committed to restoring a full 24-satellite constellation by 2010, but it's not yet compatible with GPS or Galileo, even though talks are in progress.
Lastly, China's 24-satellite system is called Compass, though it's only in the planning stage. The country is threatening to use an encrypted signal which overlays the US government's M-Code GPS broadcast. That would mean that in wartime, the US wouldn't be able to block Chinese GPS without blocking its own GPS too.
For the time being, there's little that the general public can do in terms of making sure their satnavs keep going. However, the US military relies on GPS to target missiles and help soldiers navigate. You can bet that even though they might not care about your iPhone, they're not going to let a situation arise where military tech stops working.
Update: The Air Force has responded. See news link below.