SATELLITES and astronauts orbiting the Earth have little to fear from the wind and rain of a storm far below 鈥� but the lightning might be a different matter.
Bolts of lightning are already known to produce X-rays and gamma rays. Now Joseph Dwyer of the Florida Institute of Technology and colleagues have discovered that lightning in the lower atmosphere also flings a shower of high-energy electrons towards space (Geophysical Research Letters, ). According to the team鈥檚 satellite measurements, each electron is 100 times more energetic than the photons of X-rays used for medical imaging. This means they would easily penetrate the radiation shielding fitted to satellites or the space shuttle.
Dwyer thinks these electrons are produced when gamma rays from the lightning hit gas molecules in the atmosphere. If this happens at altitudes of 40 kilometres or more, the electrons could slip through the thin air and escape into space, he says. Once there, our planet鈥檚 magnetic field whips them around the globe.
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A few lightning flashes are unlikely to produce enough electrons to disrupt satellite or spacecraft electronics, but the particles might pose a threat if the Earth鈥檚 magnetic field turns out to trap them for months, allowing them to accumulate, says Dwyer.
