Earth no passive victim of solar storms, NASA says
Date: 10-May-02
Country: USA
Author: Maggie Fox, Health and Science Correspondent
The Earth's outer atmosphere works as a heat shield to deflect and absorb some of the damaging energy, but in the process creates a billion-degree cloud of electrified gas that sets up loops of multimillion amp electric current.
Scientists at the U.S. space agency said they were somewhat surprised by the data from NASA's Imager for Magnetopause to Aurora Global Exploration (IMAGE) spacecraft, which has been watching what happens when solar storms hit the planet since it was launched in 2000.
"We knew this was going on but we didn't really know the whole range of dynamical behavior or time scales. We were really surprised how fast it all happens," Janet Kozyra, senior research scientist at the University of Michigan, said in an interview.
The solar wind blows constantly at an average speed of 250 miles per second (400 km per second).
It has long been associated with geomagnetic storms on Earth - it is the cause of the Aurora Borealis, or Northern Lights. IMAGE has allowed scientists to see the other side of the storms, from space.
The result is dramatic. IMAGE data, translated into visuals by computer, shows the superheated gas called plasma streaming from the Sun and hitting the Earth's outer atmosphere. Most is deflected but some starts a reaction with the atmosphere itself.
EARTH THROWS OFF OXYGEN
"It shows bursts of hydrogen and oxygen coming out of Earth's atmosphere," Stephen Fuselier, manager of the Space Physics Laboratory at Lockheed-Martin Advanced Technology Center in Palo Alto, California, told a news briefing.
"The timing is most important - there is a direct input from the solar wind. The Earth responds immediately by ejecting a part of the atmosphere."
It is a very small part, Fuselier stresses - a stream of charged oxygen atoms. Each storm accounts for about 100 tonnes of oxygen expelled into space. "That is about the air volume in the Louisiana Superdome," Fuselier said.
"That sounds like a lot by human standards but in fact Earth's atmosphere is much, much larger than that." He said even billions of years of storms would not measurably deplete the Earth's atmosphere.
The moment it hits space, this oxygen becomes super-charged in bursts that can also been "seen" by IMAGE. Some of it loops backs into the atmosphere but much gets caught up in the solar wind and is carried away.
"It has gained 100,000 times the energy it had when it left the atmosphere so it is very pumped up," Fuselier said.
"When it plunges into the atmosphere, these strong currents are generated. They transform the mid-latitudes from their usual calm state into kind of a maelstrom that has direct effects on our daily lives."
Such storms have knocked entire power grids offline and can interrupt radio broadcasts and satellite signals - including global positioning satellite or GPS technology relied upon by hikers, marine traffic and soldiers in the field.
"This is "how space storms reach down into the Earth and touch our daily lives," John Foster of the Massachusetts Institute of Technology Haystack Observatory told the briefing.
Scientists say understanding how the Earth's own atmosphere is involved will help them find better ways to forecast these storms and perhaps even find ways to minimize their effects.
