Two years ago, the Earth barely missed getting blasted by an extremely powerful solar storm. Most of us had no idea. But had it hit us, the storm could have knocked out power grids, left millions of people without power for months, and caused widespread chaos.
NASA recently posted new details on this unnerving close call. On July 23, 2012, the sun unleashed two large coronal mass ejections — bursts of charged plasma — and sent them hurtling toward Earth's orbit. This was one of the most powerful bouts of space weather seen in more than 150 years.
Had those bursts hit the Earth's magnetic field, they could have induced strong ground currents capable of overloading our electric grids and knocking out transformers, leaving entire regions without power.
Fortunately for us, the solar eruption missed the Earth by about a week (instead, it hit one of NASA's observational spacecraft, STEREO-A, which is how we learned about it). But that's a little too close to comfort for some scientists. "If it had hit, we would still be picking up the pieces," Daniel Baker of the University of Colorado told NASA.
Space-weather enthusiasts have long warned about the potential for catastrophic solar storms. A massive geomagnetic storm in 1859, known as the "Carrington Event," famously wreaked havoc on telegraph lines around the world. An event that size today could, potentially, cause far more damage to crucial power grids, pipelines, and satellites. (The July 2012 eruption was deemed a "Carrington-level event.")
In a worst-case scenario, a massive solar storm could leave 20 to 40 million people in the Northeast without power — perhaps for years — as utilities struggled to replace thousands of frazzled transformers from Boston to Washington DC. That's according to a sober assessment last year by Lloyd's of London, the world's oldest insurance market. The cost? As much as $2.6 trillion.
The good news is that we're not totally helpless. In recent years, as I've detailed before, businesses and government agencies have been devising plans to cope with disruptive space weather — from hardening power grids to rerouting flights that might get disrupted by geomagnetic storms. But even so, it's hard to protect against a truly massive storm, and it doesn't help that we're about to lose some key observational satellites.
So here's a rundown of why solar storms can cause so much trouble, how we might defend against them — and whether a big one might hit us anytime soon:
How a solar storm could cause widespread blackouts
The biggest concern when it comes to space weather is the possibility that a solar-induced geomagnetic storm could do serious damage to our power grids.
Here's how this would work: At certain points in the sun's cycle, as sunspots appear and flares erupt, the sun will occasionally eject part of its outer atmosphere — a cloud of fast-moving charged particles. If this "coronal mass ejection" hits the Earth's magnetic field in just the right way, it can induce a strong ground current that can travel through power lines, pipelines, and telecom cables.
If those currents are large enough, they can overload electric grids — which is exactly what happened in Quebec in 1989. But a truly severe storm could fry a significant number of high-voltage transformers. Those can often take years to replace, as many weigh up to 400 tons and are custom built, with intricate supply chains. In the meantime, millions of people could go without power.
According to the Lloyd's report, the Northeastern United States is one of the places most at risk, thanks to its aging power grid and unique geologic features (see map). Even a storm that knocked out just 20 key transformers would be "extremely concerning." And in a doomsday scenario, 40 million people could go without power indefinitely.
That wouldn't be good. Modern society relies on electricity for a great many things — and we don't do very well without it. One 2004 study by Carnegie Mellon University found, for instance, that a large number of Pittsburgh's services were wildly unprepared for an extended blackout. Half the city would lose water after three days if the city's electrical pumps couldn't be revived. Grocery stores, gas stations and cellphone networks would be knocked out. Most hospitals have backup systems in place, but emergency rooms would be strained if the air conditioning went out during a heat wave.
"The absence of such fundamental services could lead to major and widespread social unrest, riots and theft," the Lloyd's report warned.
How to protect the grid from solar storms
Not all is lost, though. Power utilities could try to take precautions if they had advance warning of a major solar storm headed their way. Using existing satellites, the National Weather Service's Space Weather Prediction Center in Boulder, Colo., can detect an incoming event that's about 30 minutes from hitting Earth.
Grid operators would then have to react quickly. For example, PJM Interconnection operates a major portion of the US power grid from Illinois to the District, supplying power to some 60 million people. After receiving a warning, its human operators could redispatch electricity to reduce the flow of current from west to east. That would minimize the grid's vulnerability to ground currents, Frank Koza, the executive director of operations support at PJM, said at a space weather conference in Silver Spring I attended back in June 2013.
But there's a limit to how much strategies like those can help. "The one we're really concerned about is extreme space weather, a Carrington-level event," Koza said then. "What would happen in that scenario? I would have to tell you we don't really know."
In theory, there are technologies that could harden the grid and protect against stronger storms, such as capacitors that can help block the flow of ground currents induced by a geomagnetic event. In Quebec, the Canadian government has spent about $1.2 billion on these technologies since the 1989 blackout.
One downside is that many of these technologies are pricey and could make the current grid somewhat less efficient during normal times. "We've designed our power lines to work efficiently under perfect conditions — long transmission lines, high voltages," Chris Beck of the Electric Infrastructure Security Council told me last year. Unfortunately, those characteristics also make the grid particularly vulnerable to a solar storm. There's a trade-off.
In recent years, the federal government has started paying closer attention to the issue. In 2012, the Federal Energy Regulatory Commission issued an order that would eventually require grid operators to prepare both operational and technological responses to a space weather event. But utility executives think it could take a few years to bolster protection for the grid.
Space weather can cause all sorts of other chaos, too
The destructive blackouts get all the attention. But solar storms and space weather can create all sorts of lesser havoc as well.
Take air travel. Nowadays, airlines run a number of commercial flights over the poles, such as routes between Atlanta and Tokyo. But if the companies get a last-minute warning from the Space Weather Prediction Center of a geomagnetic storm, the planes often have to divert their routes away from the poles or risk losing radio contact with the ground. These diversions can cost thousands of dollars.
Back in 2013, Joseph Kunches, a scientist at the Space Weather Prediction Center, told me that we're still learning about other activities that could potentially be disrupted by various types of solar weather. Satellite communications can go awry. Pipelines can corrode from ground currents. Even human space travel faces a threat.
"Radiation is a big issue for space travel — particularly once you get away from the Earth's magnetic field," Kunches said. Astronauts working outside the Earth's protective shield can be particularly vulnerable to bursts of solar radiation, which can have harmful health effects. That means that if we ever got serious about, say, traveling to Mars, we'll need a better grasp on space weather.
And there are still plenty of unknowns, such as the potential impact of solar eruptions on GPS technology. It's possible that even solar storms could degrade the signal as it makes its way from the satellite to the ground. GPS is built into so much of the modern economy — from navigation to geophysical exploration by oil and gas companies — that any interference with those signals could prove quite costly.
It'd be helpful to have more satellites to track these storms
One big problem we face in preparing for space weather is that it's unclear what we need to prepare for. Minor impacts and storms occur fairly often. But when might we expect a Carrington event? Or even something like the Quebec storm in 1989?
In February, Pete Riley of Predictive Science Inc. published a paper in Space Weather suggesting that the Earth has a 12 percent chance of getting hit by a Carrington-level event in the next 10 years. That's definitely a number we'd like to pin down.
And there's plenty more that space scientists are still trying to grasp. It's still difficult to predict, for instance, whether a solar outburst will actually create a storm when it hits Earth. A great deal depends on how a coronal mass ejection interacts with other solar winds as it moves toward us. Kunches likened it to knowing that a hurricane is coming, but not being able to measure its barometric pressure.
Scientists who study space weather say it would be useful to have more spacecraft studying the sun, to give us more advance warning of storms. But, if anything, our alert systems are about to get worse, not better.
Right now, NASA operates four space satellites positioned between the Earth and the sun, which together can provide roughly 30 minutes' warning of a major solar eruption. But these satellites are all reaching the end of their planned lives (and fuel tanks), and there's only one replacement satellite scheduled to launch in 2014.
"There's a real need for a truly operational, 24-hour-a-day, seven-day-a-week space weather observatory," Daniel Baker of the University of Colorado told me last year. "But right now, we don't see that coming from policymakers or the agencies that would have to step up."
Further watching: Here's a video of the 2012 eruption: