The Sun has been hurling plasma at Earth for billions of years, but the next direct hit could damage power grids and other infrastructure – immobilising the technology that underpins civilisation.
For more than a week, Nasa officials cautiously watched as vast plumes of material, at temperatures of tens of millions of degrees, arced from the far side of the Sun. Then the culprit spun into view: a region of sunspots more than 13 times the diameter of Earth, bubbling with volatile magnetic fields. Then, at about 1 am South African time, the region erupted, releasing a pulse of hot, electrified gas that shot towards the planet at millions of kilometres an hour.
It was 28 October 2003, and in the Service Module of the International Space Station, astronaut Michael Foale and cosmonaut Alexander Kaleri had just downed coffee as they prepared for the first full working week of their 195-day mission. The station’s orbit was sweeping the craft towards the South Atlantic Anomaly, an area above the eastern coast of South America where high-energy particles from the Sun become concentrated.
Mission control called, Foale remembers. “They said, ‘Hey, we’ve got some big events coming. We recommend you shelter in your crew station, Mike’.” With the radiation units on his personal dosimeter ticking upward, Foale floated 60 m down two long tunnels to his sleeping quarters near the front of the station. He closed himself in the coffin-like room, lined with thick polyethylene foam bricks to shield his body from the protons flying through the station – the product of one of the most powerful solar flares ever recorded.
Outside, the craft glided through a curtain of brilliant green light – an aurora, created by electrons colliding with oxygen in Earth’s atmosphere. “It was very dramatic and quite spectacular,” Foale says. But to be enveloped in that energy is unsettling. “Obviously you think, this is not good,” he says.
At 1:30 am, a satellite stationed between the Sun and Earth observed the star gain an ominous halo, the telltale sign of a coronal mass ejection (CME). The billion-ton belch of magnetised plasma reached our planet the following morning. It slammed into Earth’s magnetic fi eld, which vibrated like a bell, and in a manner analogous to a moving bar magnet raising currents in a coil of wire, the CME sent powerful electric currents coursing through the planet. Those ground currents flowed into power lines; electric grids around the world strained.
In North America, utility companies scaled back generation. In Sweden, a high-voltage transformer blew, blacking out the city of Malmö for almost an hour. The barrage of solar particles continued for days, interfering with satellites and radio communications; auroral lights danced across the sky as close to the equator as Florida and Australia. Roughly a week later, the Sun’s most active regions rotated out of alignment with the planet. No lives were lost, but the storm had caused many hundreds of millions of dollars in damage.
The Sun’s activity roughly follows an 11-year cycle, and severe space weather tends to cluster around each cycle’s peak. The sun is now entering the peak of Cycle 24, as evidenced by powerful solar storms it unleashed in January and March this year. Those storms had little effect on Earth, largely due to chance: the orientation of the planet’s magnetic field caused much of the radiation to slide over it. The next big CME will test that luck.
This deeply worries John Kappenman, founder of Storm Analysis Consultants and an expert on the effects of geomagnetic storms. His detailed investigations of the so-called Halloween Storm of 2003 found that it, too, had been dampened by the alignment of Earth’s magnetic field. And yet it still blacked out an entire city and stressed continental power grids. If the planet had absorbed the full brunt of the CME, the blackout could have had far more severe repercussions.
“If you lose electricity, within a matter of days you essentially lose almost everything else,” Kappenman says. “After the initial blackout, we wouldn’t really understand the seriousness of the situation until several days went by without having things restored. We’d rapidly lose the ability to provide the necessities for modern society.”
2 This may seem like doomsaying, but the historical record suggests otherwise: the Halloween Storm, in fact, appears minor compared with several earlier events. In March 1989, a geomagnetic storm knocked out a high-voltage transformer at a hydroelectric power plant in Quebec, plunging the province into a 9-hour blackout on an icy winter night. A storm that enveloped Earth in May 1921 sparked fires in telegraph offices, telephone stations and railroad routing terminals connected to nascent power grids. The most extreme observed storm of all, called the Carrington Event, occurred in September 1859: it caused geomagnetic currents so strong that for days telegraph operators could disconnect their equipment from battery power and send messages solely via the “auroral current” induced in their transmission lines.
“The physics of the Sun and of Earth’s magnetic field have not fundamentally changed, but we have,” Kappenman says. “We decided to build power grids, and we’ve progressively made them more vulnerable as we’ve connected them to every aspect of our lives. Another Carrington Event is going to occur some day.” But unlike in 1859, when the telegraph network was the sole technology threatened by space weather, or in 1921, when electrification was in its infancy, today’s at-risk systems are legion.
Over the past 50 years, global powergrid infrastructure has expanded tenfold. Meanwhile, utilities have shifted to higher operating voltages, which increase the efficiency of electricity transmission but make equipment less resistant to unregulated ground currents. As the grid has grown, so too has the practice of importing and exporting electricity between regions and even countries: a streetlight in upstate New York may be powered by a hydroelectric plant in Quebec; a neon sign outside a Tijuana nightclub may glow because of a natural-gas plant in southern California. This interdependency increases the risk of widespread collapse. Humans have effectively created continent-size antennae – all exquisitely tuned to soak up currents caused by space weather.
Over the years, Kappenman has undertaken a series of studies underwritten by various branches of the federal government. He has consistently found that a great geomagnetic storm, striking with little forewarning, would overheat hundreds or thousands of high-voltage transformers in the US grid, melting crucial components and effectively crippling generation capacity. Building replacement transformers at current production rates would take up to 10 years, during which time more than 100 million people would be without centrally provided power. This would cost the US economy an estimated R8 trillion to R16 trillion in the first year alone.
Last year, the US Department of Homeland Security asked an independent group of elite scientists, the JASON Defence Advisory Panel, to analyse Kappenman’s claims. In its November 2011 report, the panel expressed scepticism that his worst-case scenario could occur, but agreed that the US power grid could suffer severe damage from a geomagnetic storm. The scientists called for more spaceweather safeguards, including hardening electrical infrastructure and bolstering America’s ageing network of Sun-observing satellites.
Physicist Avi Schnurr, who presides over the non-governmental Electric Infrastructure Security Council, is among those who doubts that modern society will successfully address the problem. “If a Carrington Event happened right now, it probably wouldn’t be a wake-up alarm – it would be a good-night call,” he says. “This is a case where we have to do something that is not often successfully achieved by governments, and certainly not by democracies: we have to take concerted action against a predicted threatening event without having actually experienced the event itself in modern times.”
Protecting the grid is, in principle, relatively straightforward. Most highvoltage transformers connect directly to the ground to neutralise power surges from lightning strikes and other transient phenomena – but that also allows geomagnetic currents to flow upward. Experts estimate that electrical resistors or capacitors, which would sever that connection, could be installed at critical locations (such as near power plants or major cities) within a few years. In practice, however, it’s not so easy: US power companies have balked at voluntary installation of such devices, which could cost about R800 000 per transformer.
Peter Pry, a former Central Intelligence Agency official and staff member on the US House Armed Services Committee, has tried to spur legislative action on the threat of space weather. He has also watched in frustration as bills mandating protection of the grid repeatedly went nowhere. “The real danger here isn’t astrophysical, it’s institutional,” he says. “The threat to everyone belongs to no one.”
3 POWER OUTAGES wouldn’t be the only cause of cascading failures in the event of extreme space weather. Jane Lubchenco, head of the National Oceanic and Atmospheric Administration (NOAA), points out that highly charged particles can also degrade the precision of GPS satellites. Signals from these networks allow receivers to calculate geospatial positioning and measure time to billionths-of-a-second accuracy. Besides providing directions for road trips, they synchronise cellphone conversations, orchestrate air traffic, and guide fleets of emergency vehicles.
“Today, most financial transactions are date-stamped with GPS, and GPS guides the dynamic positioning of most deep-ocean oil and gas operations,” Lubchenco says. “Can you imagine the fi nancial disruption that a GPS outage would cause? Can you imagine the Deepwater Horizons that would occur if drilling platforms received erroneous GPS information?”
For now, the only way to ensure that power grids and satellite networks withstand another Carrington Event would be to pre-emptively shut them down when a big storm is likely to occur. “That’s really not a good solution,” Kappenman says. For one thing, each self-enforced outage would cost billions in lost productivity. For another, he says, “forecast systems probably aren’t ever going to be precise enough to avoid false alarms”.
Thomas Bogdan, former director of NOAA’s Space Weather Prediction Centre in Boulder, Colorado, acknowledges “our ability to forecast is actually fairly poor”. CMEs and solar flares will be particularly diffi cult to predict without better theoretical models of the circulation of plasma in the Sun, but CMEs reliably occur three or four times a day during our star’s activity peak, and approximately once a week during solar quiescence. “The only reason we really get by is that the Sun has a regular activity cycle,” Bogdan says.
The prediction centre relies on constant surveillance of the Sun for the slightest indication of a threatening event. Initially, this comes from ground-based observatories operated by the US Air Force and a NOAA satellite network watching for the telltale X-ray pulses that signal solar flares. But only a few satellites – including the Solar and Heliospheric Observatory (SOHO) and the two Solar Terrestrial Relations Observatory (STEREO) spacecraft – can detect whether a radiation storm or CME is actually headed towards the planet. The Advanced Composition Explorer (ACE) can measure the intensity and magnetic orientation of any CME that sweeps by it. But 20 to 50 minutes later, forecasters can merely watch the storm unfold on Earth.
Disturbingly, both SOHO and ACE are well past their nominal lifetimes, with no certain replacements. “Once SOHO ceases functioning, probably in the next year or so, we won’t have its unique ‘looking down the barrel of a gun’ perspective on the Sun for forecasting Earth-directed CMEs,” says Sten Odenwald, an astrophysicist affi liated with Nasa’s Goddard Space Flight Centre.
ACE has sufficient propellant to continue operations until roughly 2024, but there are no guarantees its instruments will last that long. Without ACE, Odenwald says, “we’ll (still) be able to see a CME coming towards us, but we won’t know whether its interaction with Earth’s magnetic field will cause major fireworks or be relatively harmless”.
STEREO and another satellite, the Solar Dynamics Observatory, may be able to compensate for SOHO’s eventual loss, but Lubchenco and other experts unanimously believe that allowing ACE’s unique observational capabilities to expire would constitute a blind spot too large and risky to ignore. “Another great geomagnetic storm probably won’t happen tomorrow, but that doesn’t mean we shouldn’t worry,” Bogdan says. “The good news is, we’ve got time to prepare for this, but the bad news is, if we don’t hedge our bets and buy down some risk, one day we’re gonna get clobbered.”
In fact, a spacecraft that could replace ACE currently sits in storage at Goddard’s facility in Greenbelt, Maryland. The Deep Space Climate Observatory, or DSCOVR, is fully assembled and all but ready for launch – Nasa simply lacked the funding to launch it into space seven years ago. As part of the Obama administration’s budget request for 2012, NOAA would receive R380 million to refurbish and launch DSCOVR to act as ACE’s replacement, but the initiative died in the House of Representatives.
After Foale rode a Soyuz TMA-3 capsule back to Earth in April 2004, he had blood drawn for an experiment that monitored his chromosomes. “Roughly, the rate of damage to my white blood cells went up by a factor of 10,” he says. It dropped back down within the year. “Life has been dealing with radiation since it began,” Foale says. “Repair mechanisms in the cells are very sophisticated.”
Human society, on the other hand, has evolved to be more fragile – complex, yet defenseless against a storm of solar radiation. Meanwhile, the Sun continues to seethe.
How a solar storm works
During a coronal mass ejection, the Sun violently blasts high-energy particles travelling several million kilometres an hour into space. When these particles sweep into Earth’s magnetosphere a day or so later, they set off a geomagnetic storm.
1 High-energy protons and electrons pass through spacecraft such as the International Space Station, damaging electronics and degrading solar arrays.
2 They also heat and expand the upper atmosphere, which increases drag on satellites, reducing their lifetimes in orbit.
3 Earth’s ionosphere becomes distorted with radiation, and plasma bubbles form. GPS signals scintillate, or break up, as they pass through this region, disrupting the triangulation of points necessary for precise navigation.
4 Ionised particles also affect the propagation of radio waves. Aircraft flying above 85 degrees latitude rely exclusively on high-frequency radio communications, and so may be rerouted.
5 Vibrations in Earth’s magnetic field induce strong electric currents in the ground. These follow the path of least resistance into oil and gas pipelines, causing corrosion.
6 They also flow into power-grid infrastructure such as transformers, which can blow out from the sudden burst of unregulated current.
A handful of satellites keep instruments trained on solar activity, detecting radiation storms hurtling toward Earth. Half could fail at any time. – Dalene Rovenstine
Solar and Heliospheric Observatory (SOHO)
Planned mission length: 2 years
Launch: 2 December 1995
SOHO uses its extreme ultraviolet imaging telescope to generate high-resolution images of the Sun’s corona and predict space weather in real time. Nasa lost connection with SOHO for six weeks in 1998; the satellite now operates without a gyroscope for maintaining orientation.
Advanced Composition Explorer (ACE)
Planned mission length: 5 years
Launch: 25 August 1997
The satellite is equipped with six high-resolution spectrometers and three instruments that study solar wind and high-energy particles accelerated by the Sun. After 15 years in space, ACE can still provide about an hour’s advance warning of geomagnetic storms.
Solar Terrestrial Relations Observatory (STEREO)
Planned mission length: 2 years
Launch: 26 October 2006
The two satellites in the STEREO mission study coronal mass ejections, leading to more accurate alerts for solar flares. The craft reached a major milestone on 6 February 2011: achieving 180-degree separation, which allowed a 360-degree view of the Sun for the first time ever.
Solar Dynamics Observatory (SDO)
Planned mission length: 5 years
Launch: 11 February 2010
SDO’s suite of instruments provides insight into how the Sun’s magnetic field is generated, structured and converted into violent solar events – at near-IMAX-quality resolution.
Geostationary Operational Environmental Satellites (GOES)
Planned mission length: 10 years
GOES-13 launch: 24 May 2006
GOES-14 launch: 27 June 2009
GOES-15 launch: 4 March 2010
Besides keeping a steady eye on Earth, GOES-15 – equipped with a solar X-ray imager, a solar X-ray sensor and an extreme ultraviolet sensor – helps NOAA forecast space weather. GOES- 13 backs up 15 during eclipses; however, its X-ray sensor is not reliable. GOES-14 is orbiting in storage mode until needed.