Extreme Solar Storm Strikes Earth
Forecasters predict stormy space weather even as they face a budget drought
PHOTO: European Space Agency and NASA
An extreme ultraviolet image of the Sun shows one of the largest flares in decades to erupt from its surface. The eruption was so intense it overwhelmed the imager on the Solar and Heliospheric Observatory satellite, producing the horizontal artifacts surrounding the flare.
Perhaps it was a sign from on high. On 30 October, as lawmakers in Washington, D.C., were considering the fate of the U.S. solar weather forecasting service, the most powerful solar storm in years rained high-energy particles into Earth's atmosphere. The National Oceanic and Atmospheric Administration (NOAA) Space Environment Center, in Boulder, Colo., correctly predicted to within a few hours the arrival of a series of huge geomagnetic storms that hampered high-frequency radio communications, knocked out satellites, 1203nsol01.jpgand caused an electricity blackout. The storms were some of the strongest on record, and unseasonable. Solar weather follows an 11-year cycle of activity that peaked three years ago.
The storms were the result of eruptions at the Sun's surface that belched forth X-rays and other photons, followed by clouds of charged particles that struck Earth at high speed. ”It took the [first major] geomagnetic storm just 19 hours to reach Earth after it occurred on the Sun,” says Larry Combs, a space weather forecaster at NOAA. ”That's one of the fastest-traveling solar storms this cycle.”
Affected are Earth, skies, and space
Solar storms can cause all manner of disruptions in and around Earth, including geomagnetically induced currents (GICs) that course into and out of the power grid and can trip circuits and stress transformers [see ”Shielding Grids from Solar Storms,” IEEE Spectrum, November 2000, pp. 55-60].
To anticipate such events, a number of utilities in North America, the United Kingdom, and South Africa rely on a sensor network called Sunburst, which monitors GICs in a number of transformers and warns of any region-wide problems. ”Our system gives a picture in near real time of whether [we're seeing] a major storm,” says Dave Fugate, president of Electric Research and Management Inc. (Pittsburgh), which operates Sunburst. Sites in the network registered close to 200 A of GIC. ”That's about as high as we've seen them since we came on line [in April 2000],” notes Fugate.
In the latest storms, electric power grid operators in the northern United States and Canada experienced power surges resulting from the storm. But evidently the only electricity blackout occurred in Malmö, Sweden.
To protect airline passengers and flight crews against bombardment with subatomic particles, the U.S. Federal Aviation Administration warned pilots to stay below 25 000 feet when flying near the poles in order to avoid excess radiation. Probably the most serious single effect of the storm, however, was on an expensive Japanese satellite, which was totaled.
Most satellite fleets weathered the storm with relatively little special effort except for orbiters maintained by Japan's space agency, JAXA. It reported the temporary shutdown of a communications satellite, Kodama, and the permanent loss of its Earth observation satellite ADEOS-II (also called Midori-II). The loss of ADEOS-II, a 120-billion yen (US $1.1 billion) craft launched only in December 2002, is considered a big blow to international confidence in Japan's space program and satellite industry. Its predecessor, Midori-I, also failed prematurely.
The exact cause of ADEOS-II's failure is under investigation, but satellites are vulnerable to solar storms in a number of ways. Satellite imaging systems can be disrupted by high-energy particles, and since some satellites orient themselves using stars, they may have trouble navigating. Electrons and ions in the solar wind can also charge up parts of the satellite, causing arcing, which can damage their internal electronics. In addition, the storm heats the upper atmosphere, causing air to rise and drag on craft orbiting at up to1000 km. So satellites have to use extra fuel to maintain their orbit.
A no to NOAA?
Meanwhile, as damage is assessed, space weather forecasters remain at sea. President George W. Bush's budget requests $8 million for NOAA's Space Environment Center, but the House of Representatives proposed only $5.3 million, while the Senate has canceled all funding, with the expectation that NASA or the Air Force would take over the job. (Representatives from those agencies stated during a hearing of the House Subcommittee on Environment, Technology, and Standards that they would really rather not take on that task.) At press time, the center's fate remained unresolved.