Solar bursts interfere with GPS

Stephen Withers
Friday, 06 April 2007 03:42

Science - Space

Cornell University researchers have found that a powerful solar flare occurring last December caused an "unprecedented" burst of radio noise that interfered with the accuracy of many GPS devices and prevented some from determining their position.

"In December, we found the effect on GPS receivers were more profound and wide spread than we expected," said Paul Kintner, professor of electrical and computer engineering at Cornell University. "Now we are concerned more severe consequences will occur during the next solar maximum."

Solar activity follows an 11-year cycle, with the next peak due in 2011.

"This solar radio burst occurred during the solar minimum, yet produced as much as ten times more radio noise than the previous record," said Dale Gary, professor of physics at New Jersey Institute of Technology.

"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. This was enough to swamp GPS receivers over the entire sunlit side of Earth."

Apart from vehicle tracking and navigation systems, GPS is also used by surveyors, foresters and miners, among others. Some countries incorporate GPS receivers into cell phones to determine their positions. It is even used as a time base to ensure distributed systems are accurately synchronised.

"[T]he size and timing of this burst were completely unexpected and the largest ever detected," said Anthea Coster of MIT's Haystack Observatory. "We do not know how often we can expect solar radio bursts of this size or even larger."

The results of the Cornell study were announced at the first Space Weather Enterprise Forum, held this week in Washington DC.