Earth's Space-Storm Shield Offers Protection -- At A Price

New observations from a NASA spacecraft reveal that a layer in the Earth's outer atmosphere acts like a heat shield by absorbing energy from space storms and reducing their ability to heat the lower atmosphere. However, it imposes a heavy toll for its services by creating a billion-degree cloud of electrified gas, or plasma, that surrounds the planet.

The plasma cloud is so ferociously hot, its particles act like radiation, occasionally disrupting satellites in mid- to high-altitude orbits. This discovery from NASA's Imager for Magnetopause to Aurora Global Exploration (IMAGE) spacecraft confirms the Earth actively participates in space storms.

Although past space missions gave provisional evidence for this behavior, IMAGE provides the first global picture of the active role Earth's ionosphere plays in space storms, which is very different from the earlier view that the solar wind itself supplied the energetic particles responsible for these storms.

For the complete article on what the new IMAGE observations reveal, go to: http://www.gsfc.nasa.gov/topstory/20020509imagessu.html