Researchers may have found the source of satellite-damaging space weather and the brilliant Northern Lights.
Solar storms can cause extensive electrical blackouts and satellite failure. A new study suggests the phenomenon is caused by solar energy that is stored in the Earth's magnetic field and then is "explosively" released, a UCLA press release reported. The explosion powers the Earth's radiation belts, which causes the notorious aurora.
Researchers can watch the progression of space weather through cameras, but the solar energy phenomenon is invisible.
"Space weather begins to develop inside Earth's magnetosphere, the giant magnetic bubble that shields the planet from the supersonic flow of magnetized gas emitted by the sun. During solar storms, some solar energy enters the magnetosphere, stretching the bubble out into a long, teardrop-shaped tail that extends more than a million miles into space," the press release reported.
In a process called "magnetic reconnection" the stored energy is released, but can only be detected if the flowing particles pass by a perfectly positioned spacecraft.
In 2008 NASA's five Earth-orbiting THEMIS satellites were in the right place at the right time and noticed this reaction could be what had triggered near-Earth space weather. The only problem was there did not seem to be enough energy in the "reconnection flows" to explain the amount of energy release by the storm.
"Similar to a pebble creating expanding ripples in a pond, magnetic reconnection generates expanding fronts of electricity, converting the stored magnetic energy into particle energy. Previous spacecraft observations could detect these energy-converting reconnection fronts for a split second as the fronts went by, but they could not assess the fronts' global effects because data were collected at only a single point," the press release reported.
In the summer of 2012 two satellites, ARTEMIS and THEMIS, were able to capture data explaining the mysterious extra energy.
"The amount of power converted was comparable to the electric power generation from all power plants on Earth - and it went on for over 30 minutes," Vassilis Angelopoulos, a professor in the UCLA Department of Earth, Planetary and Space Sciences, principal investigator for ARTEMIS and THEMIS, said. "The amount of energy released was equivalent to a 7.1 Richter-scale earthquake."
In order to track this energy, researchers must track it all the way from the solar event into Earth's atmosphere. In its travels, the energy undergoes a number of changes; understanding every step of the process could help researchers gain the ability to predict space weather in the future.
The space crafts noticed "two expanding energy fronts launched symmetrically on either side of the magnetic reconnection site," one moved directly towards Earth, and the other away from it past the moon.
"We have finally found what powers Earth's aurora and radiation belts," Angelopoulos said. "It took many years of mission planning and patience to capture this phenomenon on multiple satellites, but it has certainly paid off. We were able to track the total energy and see where and when it is converted into different kinds of energy."
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