The Space Reviewin association with SpaceNews

Sun and solar flare
The most powerful solar flare in years last week served as a reminder of the dangers of solar storms to a society increasingly dependent on electronics and communications. (credit: NASA)

When the Sun sneezes

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The advance of modern technology has helped address many of the ills of human society. At the same time, though, it has created new vulnerabilities as well, as we become susceptible to phenomena that previously might have been ignored or simply considered benign. A classic example is space weather: solar flares and other activity had once been little more than intellectual curiosities beyond their ability to create brilliant auroral displays. In a world increasingly dependent on electronics and communications, though, solar storms pose a growing hazard. When the Sun sneezes, civilization runs the risk of catching a cold.

And, last week, the Sun sneezed. A class X solar flare, the most powerful in four years, erupted on the Sun late on February 14, and associated with it were a series of coronal mass ejections (CMEs), blasting charged particles towards the Earth. This storm raised concerns that it could cause everything from communications blackouts to disruptions in the power grid from geomagnetically induced currents as the storm’s charged particles interacted with the Earth’s magnetic field. Fortunately, though, the direst predictions failed to come to pass, as the storm caused only minor interference with communications.

“Space weather is certainly becoming more front and center as threats to our critical infrastructure are realized,” said Lubchenco.

The timing of the storm was good in one respect: it came just days before a session on the effects of space weather at the annual meeting of the American Association for the Advancement of Science (AAAS) in Washington. The session, scheduled long before last week’s storm with the provocative title “Space Weather: The Next Big Solar Storm Could Be a Global Katrina”, was intended to raise awareness of the threat solar storms pose to modern civilization as the Sun approaches another peak in its 11-year cycle of activity.

“The events of this week certainly underscore how important it is for us to be paying attention to space weather and to be prepared to respond and to mitigate potential impacts,” said NOAA administrator Jane Lubchenco during the session on Saturday, which featured experts from the US and Europe. “Space weather is certainly becoming more front and center as threats to our critical infrastructure are realized.”

In her comments, she emphasized that our vulnerabilities to space weather have grown since the last solar maximum in the early 2000s. One example she noted was that airlines are flying more flights near the poles in order to provide shorter and more fuel-efficient intercontinental routes. These flights rely on radio communications that can be disrupted near the poles during solar weather, forcing airlines to reroute, as they did last week. “That, in turn, resulted in individuals getting bumped from flights and increased fuel costs because of the longer trajectories” the airlines had to fly as a result, she said.

As the Sun goes through another peak in activity over the next few years, increasing the number and severity of solar storms, it raises the question of just how prepared we are for disruptions that could result from such storms. The conference session indicated that such planning is, in many cases, quite limited.

One particularly significant vulnerability is the growing reliance on satellite navigation systems like GPS, whose signals are used by a wide variety of industries for highly accurate timing data. A solar flare, though, would ionize the upper atmosphere and thus affect propagation of GPS signals through it, increasing errors or even causing outages. How are companies that rely on GPS prepared to react to its interruption in the event of a solar storm?

Stephan Lechner of the Institute for the Protection of the Citizen, a European Commission Joint Research Centre, discussed one industry in particular, telecommunications, that uses GPS for time synchronization. “Unfortunately, there’s no simple answer,” he said of an analysis of the industry’s vulnerability. Many GPS receivers used by telco companies, he said, simply assume GPS signals will always be there.

“Many of my EU colleagues who I meet with regularly in Brussels still need to be convinced that space weather is just as important as normal weather,” Lindberg said.

There’s also varying awareness of the risks, and corresponding planning, among government agencies. “At the moment, space weather is not on the National Risk Register,” a document prepared by the UK government to plan for various emergencies, said Sir John Beddington, chief scientific advisor to the British government. He added, though, that its inclusion was under consideration, and that volcanic ash was also not in the document before the eruption last year of the Icelandic volcano Eyjafjallajökull, whose ash affected aviation across Europe for weeks.

Sweden, whose northerly location makes it more vulnerable to some effects of space weather, has a greater awareness of the effects of space weather. “From a Swedish perspective, it seems quite natural and very essential, actually, to cope with space weather,” said Helena Lindberg, director general of the Swedish Civil Contingencies Agency, roughly analogous to the US Department of Homeland Security. The so-called “Halloween storm” of 2003, she noted, caused blackouts in southern Sweden for a brief time.

However, Lindberg said Swedish concerns about space weather are not shared by other EU countries. “Many of my EU colleagues who I meet with regularly in Brussels still need to be convinced that space weather is just as important as normal weather,” she said. “Here in the US you have managed to place space weather high on the political agenda. This is excellent, and it should be an incentive to the EU.”

Improving space weather forecasts

A challenge to space weather awareness and planning is predicting the timing and severity of solar storms. Long-range forecasting of solar storms isn’t feasible now, said Juha-Pekka Luntama of the European Space Agency, but in the near term “we can tell when conditions are right for a storm to take place.” An example was last week’s storm: it was preceded by several smaller flares, suggesting a bigger outburst was possible.

“Space weather is more or less where meteorology was at the end of the 1950s and going into the 1960s” in terms of forecast accuracy, said Tom Bogdan, director of NOAA’s Space Weather Prediction Center. “We are only now just beginning to bring in some of the first numerical, physics-based models into our forecast process. When that happened in meteorology those first models didn’t do so well. It took a while before we learned how to use them.”

“Right now our forecast capabilities are not as good as they need to be,” he added. The center works with its various users of its space weather forecasts to let them know what level of confidence the center has in its predictions. “By letting them know how good or bad a forecast is, they can react accordingly.”

Aiding those forecasts are data from a number of spacecraft. Of particular utility right now are NASA’s twin STEREO spacecraft, in heliocentric orbits slowing drifting ahead of and behind the Earth. This month, the spacecraft moved into positions 90 degrees on either side of the Earth, and thus 180 degrees apart from each other, allowing them to provide a complete view of the Sun. Such data allow scientists to catch solar activity before it rotates into view of the Earth, providing advanced warning of those storms. While the STEREO spacecraft will continue to drift away from the Earth, Bogdan said NOAA is studying a concept for a solar observing satellite at the Earth-Sun L5 point, 60 degrees behind the Earth, which would provide several days’ warning of solar activity before it rotates into view of the Earth.

“When people ask me what keeps me awake at night, it’s whether or not that satellite will be running the next morning when I get up,” Bogdan said of ACE.

Another key satellite for space weather studies and warnings is the Advanced Composition Explorer (ACE), located at the Earth-Sun L1 point about 1.5 million kilometers Sunward of Earth. It can provide advanced warning of the slower charged particles that follow the initial storm, arriving at Earth as long as 48 to 72 hours later. Because of its location, it can measure the severity of that charged particle front and transmit that data to the Earth at the speed of light roughly 20–30 minutes before the particles arrive, giving governments and businesses a last-minute warning to take steps to mitigate the storm’s effects.

The problem, though, is that ACE is a geriatric satellite: launched in 1997, it has long exceeded its planned lifetime. “When people ask me what keeps me awake at night, it’s whether or not that satellite will be running the next morning when I get up,” Bogdan said. ACE is likely to stop working no later than 2021, when it’s projected to use up all its propellant.

To address this, the NOAA 2012 budget proposal, released last week, includes $47.3 million to refurbish the Deep Space Climate Observatory (DSCOVR) satellite and install on it a coronal mass ejection imager instrument. DSCOVR, like ACE, would be located at the Earth-Sun L1 point, with a launch planned by 2014, near the expected end of the upcoming peak in solar activity. DSCOVR has been sitting in storage for years after being initially developed as Triana, a project instigated by then Vice President Al Gore to provide a complete view of the Earth’s sunlit hemisphere.

Slightly scary, but don’t panic

Scientists and government officials have to walk a fine line between encouraging awareness of the threat space weather poses, and thus put into place systems to predict solar storms and mitigate their terrestrial effects, but also not to overhype them. Some people cite as an example of the threat of solar weather the “Carrington Event” in 1859, a powerful solar storm named after British astronomer Richard Carrington, who studied it. The storm affected telegraph systems around the world, in some cases setting them on fire. Such a storm in today’s world could be catastrophic—the “Global Katrina” in the title of the AAAS conference session.

“Is that the reasonable worst case that we should be planning for?” Beddington asked. While that question is still being debated, he suggested that it might be too extreme of a case to base planning on. “The Carrington Event involved essentially the conjunction of a number of low probability events, so it is arguable that that really is off the scale in terms of a worst case.”

Last week’s storm generated considerable media attention, but few serious consequences, something that raises worries that the public will become complacent to the real threats of solar storms. Lubchenco said NOAA was “very careful and judicious” about communicating the severity of the recent storm, while continuing to raise awareness of potential more severe storms. “I think the watchword is: be prepared, but don’t panic.”

“It is slightly scary, and I think that’s properly so,” Beddington said. “We’ve got to be slightly scared by these events; otherwise, we won’t take them seriously.”


ISPCS 2015