OpenStreetMap
GPS Accuracy Could Start Dropping in 2010.
We've all become accustomed to using the Global Positioning System, or GPS, whether via our iPhones, car navigation devices, handheld GPS units, or even watch-based devices like the Garmin Forerunner series. The GPS system went into full operation in December of 1993, was declared a dual-use (military and civilian) system by President Bill Clinton in 1996, and in 2000 had "Selective Availability" removed to increase accuracy for civilian uses. It relies on a constellation of between 24 and 32 medium Earth orbit satellites, some of which have been operating for nearly 19 years. Unlike other national satellite navigation systems, GPS serves the entire world and is maintained by the United States Air Force 50th Space Wing.
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http://db.tidbits.com/article/10276
Discussion
Comment from Lipperlandexpress on 20 May 2009 at 16:14
It may happen that some old satellites in orbit fail or that the fuel is gone because they are at the end of life.
But this could be just a "marketing" warning from the Airforce to get more money from the congress to get modern satellites in orbit that can keep up with the planned Galileo system.
I'm happy that we get Galileo in the future for more security ( 2 independent systems) and better accuracy.
don't forget that the whole GPS system can stop working every second caused for example by a software bug.
Comment from mannequinZOD on 20 May 2009 at 16:27
It will not happen. GPS is far to important for the US military, economy and as an international positive image campaign.
Deliberate drops of accuracy available for civilians are far more likely then drops due to failing infrastructure. So just forget about the article.
Comment from jerjozwik on 20 May 2009 at 17:49
i like that marketing angle nightdive! and mannequin, im not really worried about it actually happening, i just think its interesting to think these things actually have a life span. rather then forever beeping away via solar panels.
Comment from chillly on 20 May 2009 at 18:58
Even solar panels have a limited life, especially in space where hits from debris and micro meteorites slowly kill the panel. Cosmic rays can damage any electronics especially a big flat panel outside the shield of our atmosphere.
Comment from Skippern on 22 May 2009 at 01:12
I have no fear that one selective system, whether GPS, GLONAS, the upcoming Galileo, or any other high-accuracy system will fail entirely, as there are a growing number of such systems. What is more worrying is that cosmic interference will render all satellite systems (including SBAS corrections) useless without anybody noticing. Backup correction systems such as IALA and HF/MF RTCM corrections should be more available for both small units and car navigation units, as these can discover athmospheric disturbances and transmit corrections to the units in order to either reject unhealthy satellites or correct the error that occures. The systems I use actively at work are often dual system DPS units (They avoid calling it GPS as some of this units actually do not use GPS at all) with up to 8 different independent correction systems.
I hope that I will be able to build my own car navigation system soon, and will try to make it use all three satellite systems and as many correction systems I can use without paying expensive licenses.