Europe launched its first space weather coordination centre Wednesday to raise the alarm for possible satellite-sizzling solar storms that also threaten astronauts in orbit, plane passengers and electricity grids on Earth.
Though impossible to predict, a worst-case scenario mega-storm can happen at any time, leaving the world without Internet, telephones, television, electricity and air and rail transport for days on end.
Limited precautions can be taken, but early warning is key, say experts at the European Space Agency (ESA) which runs the centre from Brussels.
"A pilot can always land a plane... because they have alternatives (to satellites) for navigation, but if they get the disturbance without warning, at the wrong time, that can be dangerous," Juha-Pekka Luntama, head of ESA's space weather division told AFP at the launch.
Even a slight satellite glitch can put navigation out by 100 metres (yards) -- enough to miss a runway.
Earth's atmosphere and magnetosphere protect the planet from radiation released during solar flares and geomagnetic storms -- some of the most severe forms of space weather.
Smaller eruptions usually have little noticeable effect -- perhaps slight problems with car navigation systems or mobile phones.
But a major solar storm on the scale of an event in 1859 that crippled global telegraph systems could have severe impacts today.
A "coronal mass ejection" -- which sends electromagnetic radiation flying towards Earth at a speed of some 2,500 kilometres (1,500 miles) per second and plays havoc with long transmission lines -- caused surges on telegraph lines so strong in 1859 that offices caught fire and operators received electric shocks.
Such a storm today could claim about 50 to 100 satellites -- 10 percent of the total in orbit, according to ESA.
But probably the biggest threat to Earth lies in electric power grid surges.
"In the worst case, what could happen is that the transformers in the power grid are damaged and in that case, replacement of the transformers can take weeks or months," said Luntama.
Even if only a small part of the grid is damaged, overloading in neighbouring systems can lead to more blackouts that spread domino-like, such as the nine-hour power blackout in Quebec in Canada in 1989.
Astronauts orbiting Earth on the International Space Station (ISS), closer to the source of the radiation, could be at high risk of a severe solar storm, as could plane crews and passengers flying over the polar regions.
Precautions would include turning off satellites to lessen the risk, reducing the load on power grids, astronauts taking cover in well-shielded part of the ISS, and planes being diverted or even grounded if communications become unreliable.
Once witnessed by space weather watchers, the fallout from a solar storm takes between 17 and 48 hours to reach Earth, depending on its severity.
The coordination centre, a central point for space weather enquiries, will draw on the expertise of dozens of European universities, research institutions and private companies.
A similar service already exists in the United States.
For the moment, the ESA service -- funded by 14 member states -- is free.
The centre started operating six months ago and is expected to be fully operational by 2020 -- part of wider, multi-billion euro ESA system that also tracks objects in space that pose a collision threat.