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Storm warning: physicist predicts solar damage

Friday, 10 March 2000

Australia's new national power grid and hundreds of satellites orbiting the Earth may have survived a recent solar particle explosion - but they might not be so lucky next time.

The warning comes from Adelaide University physicist Dr Roger Clay in the wake of last month's solar storm which hit Earth with an interplanetary shock wave of ionized gas and magnetic fields.

Dr Clay said the solar storm on 18 February - technically known as a coronal mass ejection (CME) of high-energy particles - did not cause as much damage as some had feared, but it was likely to be the first of many such explosions in the next two to three years.

A CME consists of a group of atoms, known as a plasma, which have had their electrons stripped away from the nuclei. These travel towards earth at speeds up to 500km per second.

In sufficient quantities, the wave of particles can disrupt satellites in their path and even create an electric current big enough to disturb the Earth's magnetic field, overloading electric power systems.

Dr Clay said the Sun had just begun its most active phase - known as "solar maximum" - with the February CME likely to be the first of many such explosions.

He said the last phase 11 years ago had caused a major disruption to the Canadian power system. Since then, many more satellites had been put into orbit around the Earth, many of which were not "radiation hardened".

"If the next solar storm is no worse than the one last month, then there's no problem," he said. "But of course, since the last solar maximum 11 years ago, we've got a lot more satellites and we depend a lot more on satellites. All our communication satellites, our GPS systems and these sort of satellite systems have computer chips in them." says Dr Clay.

"The computer chips are susceptible to these particles going through them because they deposit electrons in there, and that's enough to change a zero to a one in the computer memory, which could effectively disable the satellite."

Dr Clay said the solar discharge also posed a threat to the Earth because it was equivalent to a huge electric current passing by us. "That huge external current can disturb the Earth's magnetic field and induce very large currents here on Earth." said Dr Clay.

"If you've got a large loop of wire, and you've got a magnetic field going through it, a change in the magnetic field induces an electrical current through the wire.

"There is a move to integrate power grids across countries so, as in many countries, what we have here in Australia, as we've been joining up grids between the states, are huge loops of line all connected together. When the Earth's magnetic field changes quite rapidly, it can induce big currents in the national grid, and those currents may overload the system. This is what happened in Canada," said Dr Clay.

Dr Clay said CMEs would also cause major dangers for humans in space, who are without the protection of Earth's atmosphere.

"The Apollo astronauts have said that when they shut their eyes they saw 'flashes'. Those flashes were due to these particles going through their eyes," Dr Clay said.

"It's a high-radiation environment, and it can kill. It's like continuous radiotherapy. We don't have an effective protection against it, outside of the Earth's protective atmosphere.

"Right now space agencies building a new space station to orbit the Earth. Roughly one person in one hundred per year in such an environment would die from this radiation," he said.

Dr Clay said Adelaide University's Department of Physics and Mathematical Physics has been operating two radiation detectors - one for about two years, and another commissioned earlier this year - to study solar effects.

The 18 February CME was the first substantial test for the older detector, which responds to the early effects of CMEs, with the department now hoping to develop this detector into an automated solar storm predictor.

The newer detector recorded the local arrival of the solar debris at the Earth some four days later.

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