If you find your Global Positioning System (GPS) device acting weirdly, the problem might be the Sun. Researchers at Cornell University reported Wednesday that an unprecedented solar storm last December had a serious impact on GPS and other communications systems.
The findings, presented in Washington, D.C. at the first Space Weather Enterprise Forum, focused on a giant solar flare on December 6, 2006. It created a tremendous radio burst that caused GPS signals to be dropped for a large number of receivers, the researchers said.
Solar flares have been known to disrupt satellite communications and impact electricity grids before, but the researchers said the December event was different.
"In December, we found the effect on GPS receivers was more profound and widespread than we expected," Dr. Paul Kintner, Cornell professor of electrical and computer engineering, said in a statement. "Now we are concerned more severe consequences will occur during the next solar maximum." Specially designed receivers at Cornell were able to measure the impact of solar radio bursts with an unprecedented precision.
Although the burst occurred during a relatively quiet time in the Sun's "weather," it produced as much as ten times more radio noise than any previously monitored solar event, according to Dr. Dale Gray, head of the physics department at the New Jersey Institute of Technology (NJIT).
"Measurements with NJIT's solar radiotelescope confirmed, at its peak, the burst produced 20,000 times more radio emission than the entire rest of the Sun," he said in a statement. "This was enough to swamp GPS receivers over the entire sunlit side of Earth."
The December 6 burst was so powerful, it even showed up on the civil air navigation system, according to researchers at Boston College.
The episode demonstrates several key lessons for our technological society, according to Dr. Anthea Coster of the MIT Haystack Observatory.
We cannot, she said, become overly reliant on technology without keeping in mind the possible effects of space weather disruptions, which can be global and instantaneous. She pointed out that "the size and timing of this burst were completely unexpected and the largest ever detected. We do not know how often we can expect solar radio bursts of this size or even larger."
Only Now Known
Solar flares produce intense bursts of radio noise, which peak in the bands used by GPS systems. Normally, GPS signals can still be read, because the solar noise is relatively weak. Researchers say the problem is only now becoming known because the rapid rise of GPS devices has occurred in a period of relatively low solar noise. A possible solution would be to increase signal strength, but researchers said that could mean redesigning GPS satellites.
Satellite signals are used by a GPS receiver to determine location, speed, and direction, instantaneously and with an unprecedented accuracy. Airplanes and ships commonly use GPS devices, and they are indispensable for emergency rescues. Cell phones are beginning to carry them, mapmakers commonly employ them, and even banks use them to synchronize money transfers.
The next expected peak period for solar activity will occur in 2011 and 2012. A study published last year indicated that solar flares during that time could cause widespread disruption to satellite-based navigation.