Britain is better prepared for a solar superstorm than many countries, including the United States. The Royal Academy of Engineering has released a multi-disciplinary report on space weather’s impact on Britain, as part of the UK National Risk Assessment. The declassified portion of the assessment shows the level of UK preparedness in the face of severe solar storms, and outlines the dangers Earth faces from superstorms and how to avoid or mitigate damage.
Despite the fact that we depend on the Sun for every moment of our existence, we tend to take it for granted. This is unfortunate, because the Sun isn’t quite the unchanging fireball that we imagine. The Sun is a slightly variable star with a period of about 11 years. That means there are times when it’s very active and others when it’s quiescent. Currently, the Sun is coming out of an unusually quiet period when it had few if any sunspots and relatively little activity.
The sunspots are areas of intense magnetic activity and when the Sun is in a particularly active phase they’re a harbinger of solar flares, which are sudden, explosive bursts of plasma and radiation from the Sun. These flares travel at different speeds with UV and X-rays arriving at the distance of the Earth in eight minutes and the plasma showing up 72 hours later. If this energetic combination hits the the Earth's magnetosphere, it results in interactions such as the Aurora Borealis or Aurora Australis and can affect radio communications, especially at high latitudes.
This can be spectacular, but not particularly dangerous because the Earth has its own natural defenses. The Earth’s magnetosphere acts as a shield to most of the nastiness of a solar flare, protecting the planet and satellites orbiting it. Below this is the atmosphere that shields against all but the most energetic of radiations. It isn't a perfect shield, though. The protection decreases with altitude and proximity to the magnetic poles, and the more severe events can damage satellites and even affect power grids on Earth.
Superstorms are another matter entirely. These massive outbursts from the Sun occur at rare intervals and usually they miss the Earth. Our planet is in danger of being hit about once every century or two, and only one in two storms interact with the magnetosphere and cause damage. This may not seem like much of a menace, but superstorms are in the killer asteroid category. They aren't likely to hit, but if one does, it could be a major catastrophe if not prepared for. These can come in a series of geomagnetic storms lasting about two hours each, with all manner of substorms mixed in.
The potential for damage is huge. One 1989 solar event took out part of the Canadian electrical grid. In 1859, the worst confirmed solar superstorm ever occurred in what is called the Carrington Event. This was a huge geomagnetic storm caused by a superstorm roaring out from the Sun and hitting the Earth during a time of intense solar activity. It produced auroras from the Arctic to the Caribbean so bright that a newspaper could be read by the light. Telegraph systems across North America and Europe failed, and some telegraph operators received shocks.
According to the the Royal Academy report, there’s a bit of good news for those awaiting a solar apocalypse. There has been a lot of sensational news about the threat of superstorms and there have been fears that a huge flare would destroy power grids at a cost of trillions of dollars, but more recent studies indicate that only a temporary loss of power and some voltage instability is more likely. This is true even of the US grid, which is particularly vulnerable for a developed nation.
The possible effects of a superstorm-induced geomagnetic storm include the worst-case scenario of a voltage surge that would overwhelm the system, destroying vital components such as transformers and relays. Another possibility is that the storm would create voltage instability. Modern power grids are designed to work with a steady, predictable load and unexpected variations can cause problems ranging from equipment damage to a cascading blackout. Finally, there is the chance that a storm might create harmonics in the grid, which could cause problems much as mechanical harmonics can in a bridge.
The Royal Academy’s assessment of the UK grid shows that it is better prepared than that of many countries. According to the report, Britain’s power grid has some vulnerabilities, but the National Grid is working with the British Geological Survey to develop monitoring systems to deal with geomagnetic storms, and National Grid personnel regularly rehearse damage avoidance and mitigation procedures. The UK grid depends on 13 super transformers to relay power to customers. Some or all of these might be knocked out, resulting in local blackouts, but spares are kept on hand and damage could be repaired in as little as four weeks. In addition, new hardened transformer design has been carried out since 2003.
Satellites are another major area of concern regarding superstorms, but the fears that the skies would be wiped clean by the Sun turn out not to be the case. Satellites aren't as vulnerable as once thought, because engineers tend to be a bit conservative. The Academy estimates that ten percent would be knocked out temporarily for hours or days. However, there is some cause for concern because standard designs means that whole constellations of identical satellites might be affected if one of their type is.
Though satellites have some redundancy and inbuilt shielding, and coping with component degradation is included in their design, radiation would also reduce the operational life of satellites – older satellites could be knocked out early on in an event. This degradation would mean that more satellites would need to be replaced ahead of schedule. However, exactly how well current satellites would ride out a superstorm is uncertain and there is also the danger that such a storm would cause the Earth's atmosphere to expand, increasing drag on satellites. This was the cause of the loss of the US Skylab space laboratory in the 1970s, before a rescue mission could be arranged.
GNSS signals are also used for timing various systems, such as those for communications and financial trading, and even terrestrial radio broadcasts could be affected. According to the report, Britain is already equipped with devices called holdover oscillators to transmit time signals while GPS is out, although the Academy recommends that more be deployed.
Solar storms are notorious for affecting radio broadcasts, and superstorms are no exception. Shortwave broadcasts, such as the BBC World Service, might be unavailable for a while, but satellite broadcasting would not be affected because satellites operate at much higher frequencies. However, the loss of radio isn't as serious as it would have been 50 years ago, though some aircraft communications would be affected.
Another area where the Academy says that Britain is well prepared compared to the US is its mobile phone network, which is hardened and has inbuilt redundancies. Ironically, one area of vulnerability is the UK’s Terrestrial European Trunked Radio Access (TETRA) emergency communications network, which depends on GNSS signals to operate.
Protection from superstorms is partly a matter of keeping the atmosphere between us and the incoming radiation, as well as keeping a distance from the magnetic poles where the Earth’s magnetic defenses are weakest. Ground-based electronics are relatively safe from superstorm effects, though by how much is uncertain. Electronics in aircraft are another matter. Avionics would be at greater risk than circuits on the ground, but avionics are also made to be redundant and robust, so it is more a question of an increase of risk rather than a direct hazard.
Not only would the avionics be affected, so would the passengers and aircrew, who would be subjected to a radiation dose of over 20 mSv – 20 times the annual dose limit and exceeding the occupational limit for radiation workers. This sounds alarming, but it only increases cancer risk by one in 1,000 over a lifetime. According to the report, it’s astronauts who have more to fear, since they can’t get out of the way of the storm while aircraft can reduce altitude or be routed southward. Nevertheless, the Academy does recommend classifying solar storms as radiation emergencies for flight passengers and that emergency plans be developed.
There are plans by NASA and ESA to launch satellites as early warning outposts before the Solar Maximum in 2024, and the UK Space Agency is flying experimental sensors aboard NASA’s upcoming Sunjammer solar sail spacecraft to investigate the possibility of using solar sails to position warning satellites. Unfortunately, even if these early warning satellites come online, they will still only provide 15 to 30 minutes of warning.
Professor Paul Cannon FREng (sic), Chair of the Academy's working group on extreme solar weather said, "Our message is: Don't panic, but do prepare – a solar superstorm will happen one day and we need to be ready for it. Many steps have already been taken to minimize the impact of solar superstorms on current technology and by following the recommendations in the report we anticipate that the UK can further minimize the impact."
Part of this preparedness would include the establishment of a UK Space Weather Board to maintain an overview of space weather strategy across all government departments. Additionally, it's recommended that the Engineering and Physical Sciences Research Council should make sure that it continues research into mitigating the effects of solar storms.
One area of particular importance is the need to understand storms and their impact. Data on storms only goes back 170 years, which makes gauging probabilities difficult. Exactly how often they occur is unknown and though a Carrington Event will most likely happen once every 250 years, it may occur in as little as every 50 years. For this reason, the Academy recommends that information on solar storms be readily shared, that equipment standards be improved, agreed response procedures be developed and provisions for rapid decisions established.
Source: Royal Academy of Engineering
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