NASA has created a new project called "Solar Shield" in an effort to prevent damage to key transformers in the case of a severe solar storm.

In 1859, a severe solar storm called the Carrington Event occurred throughout September 1 and 2. It is the most powerful solar storm recorded in history. Offices caught on fire and telegraph operators were actually shocked and saw sparks from the storm. Sunspots and solar flares were seen on the sun from August 28 through September 2, and aurorae seen over the Rocky Mountains were so bright that gold miners awoke early because they thought it was daylight. Just before noon on September 1, Richard Carrington, a British astronomer, saw the largest flare in the sky. This large flare caused a coronal mass ejection, which is a billion-ton solar storm cloud, which took 18 hours to travel toward Earth. 

A report composed in 2008 by the National Academy of Sciences noted that a solar storm as severe as the Carrington Event could cause mass power blackouts and "permanent damage" to main transformers if it were to occur today. In fact, in 1989, Quebec experienced a geomagnetic storm much less powerful than the Carrington Event, and even still, power was knocked out for over nine hours and transformers were damaged in Quebec, Great Britain and New Jersey. In 2003, yet another geomagnetic storm milder than the Carrington Event occurred, causing transformer damage in South Africa and blackouts in southern Sweden.

Unfortunately, a report composed by the North American Electric Reliability Corporation (NERC) and the U.S. Department of Energy in 2009 warns that modern power systems, though several utilities have taken the necessary steps to strengthen and secure their power grids, have a "significantly enhanced vulnerability and exposure to effects of a severe geomagnetic storm."

To protect power systems in the event that another powerful solar storm should occur, NASA has developed a project called "Solar Shield," which has the potential to shelter high-voltage power lines that crisscross over North America. Considering the length of these power lines has "increased nearly 10 fold" since the beginning of the Space Age, it is critical to consider the affect a solar storm could have on power systems in the United States and throughout the world.  

"Solar Shield is a new and experimental forecasting system for the North American power grid," said Antti Pulkkinen, project leader and Catholic University of America research associate currently working with NASA's Goddard Space Flight Center. "We believe we can zero in on specific transformers and predict which of them are going to be hit the hardest by a space weather event."

Geomagnetically induced currents (GICs) are the main problems when it comes to power grids during geomagnetic storms. When a CME approaches Earth's magnetic field, it causes the field to shake. This quiver causes currents from the ground to Earth's upper atmosphere, and powerful GICs can trip breakers, overload circuits and melt the windings of transformers. Transformer damage leads to large-scale blackouts, and these transformers cannot be repaired in the field. They must be replaced, which is both expensive and time consuming. 

"Solar Shield springs into action when we see a coronal mass ejection (CME) billowing away from the sun," said Pulkkinen. "Images from SOHO and NASA's twin STEREO spacecraft show us the cloud from as many as three points of view, allowing us to make a 3D model of the CME, and predict when it will arrive."

The CME typically takes 24 to 48 hours to cross the Sun-Earth divide. During this time, NASA researchers at the Goddard Community Coordinated Modeling Center (CCMC) are gathering physics-based computer programs to model the CME. Thirty minutes before impact, ACE, a spacecraft stationed 1.5 million km "upstream from Earth," uses its sensors to make in situ measurement's of the CME's magnetic field, density and speed, then sends the data to the Solar Shield team on Earth. The data is fed into CCMC computers where models predict currents and fields in Earth's upper atmosphere and transmit this information to the ground. The Solar Shield team is then prepared to send alerts to utilities with details about the GICs. 

"We'd like more power companies to join our research effort," said Pulkkinen. "The more data we can collect from the field, the faster we can test and improve Solar Shield."

Solar Shield has never been tested during a geomagnetic storm, but a small number of utilities have already installed monitors at main locations in the power grid so that the team can check their predictions. Pulkkinen and his team expect the next solar maximum around 2013.