UK 'can cope with solar superstorm'
If a solar superstorm struck the Earth, the effects on the UK would be "challenging but not cataclysmic", says a major report.
An expert panel for the Royal Academy of Engineering assessed the readiness of Britain to handle a huge outburst of radiation and particles from the Sun.
It found the nation's infrastructure to be reasonably well prepared.
However, the report warns disruption is likely in a number of areas. Some power cuts would probably occur, for example.
Systems reliant on the timing signals from GPS satellites might have to resort to backup oscillators for a period of days, and aviation services could have to be limited for a while because of disruption to communications and possible upsets in aircraft avionics.
But the experts stress that it is the sum of a number of issues all happening at once rather than one or two big calamities that will test society's ability to cope.
"It will be perhaps comparable to the Icelandic volcano eruption [in 2010], or something similar, where there will be severe disruption to our way of life for a while, but it will be something we believe we can deal with," Prof Paul Cannon, the report chairman, told BBC News.
Explosive eruptions of energy from the Sun are a common occurrence.
Our star can sometimes despatch big bursts of shortwave and longwave radiation, superfast particles and colossal volumes of charged gas (plasma) in our direction.
This "space weather" can have a number of effects on modern infrastructure, from glitching electronics in orbiting spacecraft to increasing the interference heard on radio broadcasts such as those from the BBC.
But it is the impacts that would stem from a truly big eruption that concerned the RAEng panel.
It used as its yardstick the so-called "Carrington storm" of September 1859. During this eruption, the solar particles hitting the atmosphere produced auroras across the whole world, not just at high-latitude locations as is normally the case.
The experts examined how various aspects of UK life would handle these 1-in-200-year type events.
They found the National Grid to be in good shape. A big solar storm could induce currents and heating in equipment that leads ultimately to blown transformers and blackouts. But the report said many of the contingencies to mitigate such problems were already in place because of the constant threat from terrestrial weather.
"Our grid is organised as a lattice, which means it has resilience built in," commented Chris Train, the director of market operation at the National Grid. "That's very different to the Canadian grid, for example, which is point-to-point with long lines in series. You can see how that kind of system might be vulnerable to a cascade."
Satellites would undoubtedly be affected, the report said. The assessment was that perhaps one in 10 might be knocked offline by the storm. Most of these would be brought back into operation reasonably quickly, the panel found, although the experience might shorten the lifetimes of some sub-systems and components.
"Fortunately, satellites are already designed to deal with a lot of this space weather," observed one of the report's authors, Keith Ryden, a reader in space engineering at the University of Surrey Space Centre.
"Also, satellite engineers are extremely conservative people and they tend to put in big design margins, and, additionally, we have a big diversity of satellite designers these days.
"For all these reasons, we think that the effects of a superstorm, although it will lead to disruption, will be limited by these mitigating factors."
There is a particular concern about the Global Positioning System (GPS) service. A lot of utilities use the timing signals broadcast by the American sat-nav spacecraft to synchronize the operation of their networks. These broadcasts will likely be degraded, even lost, said the panel for one to three days because of disturbances in the ionosphere.
Those who were reliant on GPS timing should ensure they had back-up oscillators available, the panel said. It commended the traditional fixed and mobile phone networks in the UK in this respect, but raised a flag about the introduction of the newer 4G cellular systems. The standards underpinning the next generation of mobile phones were not as robust as they could be, the experts warned.
A GPS outage would also impact navigation in the shipping and aviation sectors. Disturbance to satellite and high-frequency radio communications would cause them problems, also. The panel noted that ships and planes had alternatives available. However, they recommended these sectors, especially planes, consider putting sensors on board to understand better the glitches that can occur in electronics.
Aeroplane avionics, for example, are vulnerable to the perturbations caused by neutron particles cascading down through the high atmosphere during a storm.
The other aspect relevant to aviation is the increase in radiation that aircrew and passengers caught in a major solar storm would experience.
Dr Jill Meara is affiliated to the Centre for Radiation, Chemical and Environmental Hazards at the Health Protection Agency. She cited the example of a London to Tokyo flight. In normal circumstances, a passenger might receive a radiation dose of 0.1 millisieverts on such a journey, she explained. If the flight was made during a Carrington storm, this dose could be as much as 20mSv.
"To put that into context, 20mSv is the same dose you get from three computed tomography (X-ray) scans of your chest, roughly," she told reporters.
"It's also the dose you might get from 2.5 years living in Cornwall where the natural radiation dose is higher because of radon coming up from the ground. Clearly, 20mSv is an unusual dose and not to be recommended, but it's not a significant dose for an individual or in public health terms."
The RAEng recommends that a UK Space Weather Board be set up by the government to lead the response to the space weather issue. It also calls for more research and more coordination with the UK's international partners.
Jonathan.Amos-INTERNET@bbc.co.uk and follow me on Twitter: @BBCAmos