GPS City’s Roxie M follows up on media claims of a failing satellite system.
We have taken the initiative to contact the US Government Accountability Office (GAO) to get clarification on the media rumors surrounding North America’s GPS constellation, and that it may stop working after 2010.
Many of the stories and articles are projecting this as being a high risk situation. The reality is a chance of less than 20%, that some of the original satellites may fail. If the weatherman predicts 20% chance of rain, most likely it won't rain at all. We should start to worry if there is a 50% chance of system failure.
These satellite failures would not be to the entire GPS satellite constellation, and would at the most affect a few of the many satellites, meaning there would still be working GPS satellites still in orbit. The GPS systems has a minimum 24 turned on at any given time. With a few satellites waiting in the reserves just incase an active one fails. You should not notice any service interruptions if the constellation falls a couple below 24. The US is in the process of replacing the current GPS Space vehicles with more robust versions.
We believe the worst-case scenario would be the HDOP (GPS Geometry) could be affected, reducing the accuracy of your GPS unit slightly during some times of the day. Most consumer applications only require 4 satellites to get high enough accuracy to navigate you car from A to B. Professional surveyors are more likely to see any adverse effects.
Original article by: US Government Accountability Office.