The solar storms that cause the stunning aurora borealis and aurora australis (or northern and southern polar lights) also have the potential to knock out telecommunications equipment and navigational systems and cause blackouts of electrical grids. With the frequency of the sun’s flares following an 11-year cycle of solar activity and the next solar maximum expected around 2013, scientists are bracing for an overdue, once-in-100 year event that could cause widespread power blackouts and cripple electricity grids around the world. It sounds like an insurmountable problem but a new NASA project called “Solar Shield” is working to develop a forecasting system that can mitigate the impacts of such events and keep the electrons flowing.
In 1859 the most powerful solar storm in recorded history, known as the Solar Superstorm, or the Carrington Event, caused telegraph systems all over Europe and North America to fail. Today, the effects of severe solar storms are much more noticeable with the total length of high-voltage power lines crisscrossing North America increasing nearly tenfold since the 1950s. This has turned power grids into giant antennas for the geomagnetically induced currents (GICs) – the ground level manifestation of space weather that can overload circuits, trip breakers, and in extreme cases melt the windings of heavy-duty transformers, causing permanent damage.
Just such an event occurred in Quebec on March 13, 1989, when a geomagnetic storm much less severs than the Carrington Event knocked out power across the entire province for more than nine hours. In addition to Quebec, the storm damaged transformers in New Jersey and Great Britain and caused more than 200 power anomalies across the continental U.S.
Although many utility companies have taken steps to reinforce their grids, with demand for power growing faster than the grids themselves modern networks are stressed to the limit and vulnerable to the effects of a severe geomagnetic storms. With the possibility of long-lasting large scale blackouts a real possibility due to widespread transformer damage the Solar Shield project leader Antti Pulkkinen believes the project can “zero in on specific transformers and predict which of them are going to be hit hardest by a severe space weather event.”
How it works
When a massive burst of solar wind, known as a coronal mass ejection (CME), is detected rising from the sun’s surface and headed for Earth, images from SOHO and NASA’s twin STEREO spacecraft would allow a 3D model of the CME to be created and predict when it will arrive. While the CME is making its way to Earth – a trip that usually takes 24 to 48 hours (although the Carrington Event CME took just 18 hours as an earlier CME had cleared the way) – the Solar Shield team would prepare to calculate ground currents.
About 30 minutes before impact the CME would sweep past ACE, a spacecraft stationed 1.5 million km upstream from Earth. Sensors aboard ACE would make in situ measurements of the CME’s speed, density and magnetic field and transmit this data to the Solar Shield team at the Community Coordinated Modeling Center (CCMC) at NASA’s Goddard Space Flight Center.
“We quickly feed the data into CCMC computers,” says Pulkkinen. “Our models predict fields and currents in Earth’s upper atmosphere and propagate these currents down to the ground.” With less than 30 minutes to go, Solar Shield can issue an alert to utilities with detailed information about GICs.
Solar Shield is still only experimental and hasn’t yet been field-tested during a severe geomagnetic storm. A few utility companies have installed current monitors at key locations in the power grid to help the team check their predictions but, with more data allowing the team to more quickly test and improve the system, they are hoping more power companies join the effort. A few good solar storms would help too with the sun being mostly quiet during the past year – something like the calm before the storm.