Arctic probe into solar storm sat-nav disruption

Sat dishes Duncan Stone The observatory in Svalbard is being used to study the impact on satellite signals

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Scientists in the Arctic have launched an urgent investigation into how solar storms can disrupt sat-nav.

Studies have revealed how space weather can cut the accuracy of GPS by tens of metres.

Flares from the Sun interact with the upper atmosphere and can distort the signals from global positioning satellites.

The research is pressing because rapid warming is attracting more vessels, tourists and mining operators.

The project is under way at a remote observatory on a windswept mountainside in the Norwegian archipelago of Svalbard in the High Arctic.

Northern Lights near Tromso The northern lights are one familiar effect of solar storms

The most familiar effect of solar storms is the creation - when the Sun's particles strike the Earth's magnetic field - of the beautiful Northern Lights.

But the scientists are hoping to understand the impact on satellite signals and then to try to develop a system for forecasting the most damaging effects of space weather.

The site was chosen for its isolation from electronic pollution and for its position in relation to the Earth's magnetic field which flows from space down towards the far North.

Violent solar activity has long been known to pose risks to satellites in orbit and to electricity networks. Aircraft flight-paths are usually altered to avoid the most northerly areas.

Less well understood is the distorting effect of the Sun on the ionosphere which GPS radio transmissions have to pass through on their way to sat-nav receivers on the ground.

Professor Dag Lorentzen shows David Shukman how solar storms affect the Earth's magnetic field

"It's like the twinkling of the stars," according to Professor Dag Lorentzen of the University Centre in Svalbard (UNIS).

"If you're standing outside looking at the night sky, some of the stars are twinkling as the intensity of the light changes - and this is basically the same for a sat receiver seeing the signal from a GPS satellite."

The effect, known as scintillation, is most acute at northerly latitudes but can even be observed in periods of quiet solar activity.

During our visit to the observatory, no solar storm was under way but the station's GPS receivers were inaccurate by between 1-3 metres when compared with the site's known location.

This is the result of the normal flow of the solar wind disturbing the upper atmosphere in high latitudes - while a solar storm can produce a far larger effect.

Opening up

Professor Lorentzen said: "If you have a very large solar storm, you can get a distortion of up to tens of metres.

"It's absolutely important to understand why this is happening so that if we know that we have a solar storm, then we might be able to predict the deviation or accuracy of the GPS signal in the future."

This matters as the retreat of Arctic ice opens up the region to new activities including oil drilling, shipping and tourism - all of which require highly accurate navigation especially for search and rescue.

But signal distortion has also been observed at much lower latitudes during solar storms so may have more widespread implications.

Dr Lisa Baddeley, another UNIS scientist working on the project, is in charge of an installation known as SPEAR, which stands for Space Plasma Exploration by Active Radar.

Dr Lisa Baddeley shows David Shukman around the observatory site

This is an array of 48 giant aerials, originally built by Leicester University but now run by UNIS. The aerials work in concert to transmit a 16MW radio beam into the upper atmosphere to mimic the effects of a solar flare.

By firing the beam into the ionosphere and measuring its effects on the particles there, Dr Baddeley and colleagues can probe the mechanisms of solar interference.

"Everyone has satnav in their cars - it's something we take almost for granted," she told me.

"What we need to research is how these GPS systems are affected by solar storms and this huge amount of energy coming into the Earth."

Bear threat

Similar arrays, such as a much powerful one known as HAARP run by the US in Alaska, have attracted controversy with questions about their true purpose. Last year a retired Russian general speculated that Russia's Phobos-Grunt mission to Mars went wrong because of the influence of HAARP.

Scientists involved in the projects have always dismissed the allegations as ludicrous.

Dr Baddeley explained that the Svalbard array is shut down by the control tower of the local airport whenever an aircraft approaches so any risk is negligible.

A more immediate hazard is posed by the Arctic wildlife. Throughout our interview, amid the field of masts, she kept a rifle slung over her shoulder - standard practice for anyone working in the open here because of the threat of polar bears.

Our visit took place during late summer but the installation has to be maintained year round including the dark days of winter.

"In the depths of the polar night," Dr Baddeley said, "when it's pitch black, and minus 20, it's reassuring to have the gun.

"And I sometimes bring a dog because dogs are the best for looking out for polar bears."

This is science at its toughest. But the more satnav becomes the electronic backbone of so much of modern life, the more valuable will be the findings gathered on this lonely hillside.

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