A new study by the NASA THEMIS mission team is the first to show that such storms can originate much closer to Earth than previously thought, overlapping with the orbits of critical weather, communications and GPS satellites. Magnetic storms can produce dazzling northern lights or hazardous particles careening toward spacecraft and astronauts, zapping them out of commission; they can disable the electrical grid, disrupt radio communications and corrode pipelines, even creating extreme aurora visible close to the equator.
An incident that illustrates the dramatic power of magnetic storms occurred in 1921, when such a storm disrupted telegraph communications and caused power outages that resulted in a New York City train station burning to the ground. And in 1972 the Apollo 16 and 17 astronauts narrowly missed what could have been a lethal solar eruption.
How electric currents in space influence the aurora and magnetic storms has been long debated in the space physics community. Because the storms occur so rarely and satellite coverage is sparse, it has been difficult for researchers to detect the dynamic process that powers those storms.
When solar wind magnetic energy is transferred into the magnetosphere, it builds up until it is converted into heat and particle acceleration through a process called magnetic reconnection. Recent observations by multiple satellites have shown that magnetic storms can be initiated by magnetic reconnection much closer to Earth than previously thought possible. The three NASA THEMIS satellites observed magnetic reconnection only about three to four Earth diameters away. Later, a weather satellite, which was nearer to Earth in geostationary orbit, detected energized particles associated with magnetic storms.
The weather satellite proved that this near-Earth reconnection stimulated ion and electron acceleration to high energies, posing a hazard to hundreds of satellites operating in this common orbit. Such particles can damage electronics and human DNA, increasing the risk of radiation poisoning and cancer for astronauts. Some particles can even enter the atmosphere and affect airline passengers.
This discovery will ultimately help scientists refine predictive models of how the magnetosphere responds to solar wind, providing precious extra hours or even days to prepare satellites, astronauts and the energy grid for the next "big one" in space.
Journal information: Nature Physics. Provided by University of California, Los Angeles.
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