The space around the Earth is more dangerous than scientists thought, according to new research. This could mean plans for lightly shielded, very cheap satellites will have to be shelved for the time being.

Researchers at the University of Colorado have discovered that a region around the planet, previously thought to be free of radiation, is actually awash with high energy particles. This so-called "safe-zone" sits in between the radiation-stuffed Van Allen belts. This region is normally shielded by the Earth's plasmasphere, but during the particularly intense solar storms last year, this was eroded somewhat and the "safe-zone" was flooded with ions. Some radiation still remains today, researchers have found.

The Van Allen belts are two torus shaped regions that sit at altitudes of 3000-6000km and 20,000-25,000km above Earth's equator. For a long time it was thought impossible for a human being to survive crossing this hostile zone. (This argument is one of the central tenets of the "Moon Landings Conspiracy" theory, which argues that the whole moon mission was faked. Shame about the lunar laser ranging retroreflector array, huh?)

Check out NASA's page for some amazing graphics of these regions.

Satellites that orbit outside the safe-zone have always carried heavy shielding to protect them from radiation in orbit. However, this shielding makes getting the craft into orbit an expensive proposition. Scientists had hoped that lighter satellites would be able to be launched that would orbit only in the safe zone. This research suggests that this wouldn't be such a good idea.

Last year's storms were unusually intense, but that doesn't mean the zone is safe. Once every 11 years, when solar activity peaks, radiation will be more than strong enough to flood the space between the Van Allen belts, and smaller peaks in the intervening years could also cause problems.

Jerry Goldstein of the Southwest Research Institute in San Antonio, Texas, told New Scientist: "It doesn't exactly shatter our hopes but it's not good." ®

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