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Currently the sun is launching some intense solar flares.


Th article I've linked also mentions how a "coronal mass ejection knocked out the power grid in Quebec" in 1989. Some powerful stuff. Thankfully the Earth's magnetic fields protect us rather well from the brunt of the force. But I wondered about those on the International Space Station? How are they protected, if it all? Surely a blackout on the ISS would mean death, so how do they prevent them?

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They are not really protected. Some 1-2mm of metal is nothing. So, god bless earth magnetic field.

To prevent blackout there is just proper onboard powergrid engineering with redundancy (which in fact exist in civil power grids too, but fails because someone wanted to save money somewhere).

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I see, so any interference with stuff on earth is because it simply hasn't been engineered to compensate, or handle, solar activity. While the ISS, of course, that would have been a major design decision. As far as protection, I guess it's only time spent on the ISS then? –  Ben Griffiths Feb 18 '11 at 10:11
There is engineering to compensate on Earth too. Bloody managers just save money everywhere even if it makes the system unstable. That's the cause. Don't understand your second part about time on ISS. –  BarsMonster Feb 18 '11 at 10:15
Sorry - I meant that they can only 'protect' themselves by not spending too much time up there. –  Ben Griffiths Feb 18 '11 at 10:17
Dear Ben, being an astronaut has always posed some risk, hasn't it? The astronauts used to be celebrated as heroes, and for a good reason. Challenger burned its crew on TV screens in front of millions of viewers in 1986. Columbia did the same thing away from screens in 2003. There have been many accidents. Flying on a spaceship is unhealthy and you will see the impact after half a year, for sure. The impact on your muscles etc. might still be more dangerous or harmful in average than the radiation or risks of a blackout. –  Luboš Motl Feb 18 '11 at 10:20
Yes. But again, it's not that dangerous (I mean yes, there are risks, but you not gonna die immidiately). Some guys in USSR spent more than 1 year on orbit and they were fine. –  BarsMonster Feb 18 '11 at 10:21
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They are protected by the metal that is specifically designed to prevent the astronauts from being hit by a large amount of solar radiation which will kill you if exposed to it.

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The induced EMF from a change in magnetic field strength (note it is a vector quantity so a change in direction also changes things), is the time rate of change in the net magnetic flux going through a closed circuit. Flux is area (normal vector) dotted with the field. So the area covered by a current loop determines the sensitivty to field changes. In the power grid on earth, dimensions are on the order or hundreds to a few thousand kilometers, so a small change in the magnetic field times a large area can generate a high voltage. The ISS is many times smaller, so induced voltages/currents should be orders of magnitude smaller. The real problem for the ISS is the ionizing radiation of the particles, either from the solar wind, or trapped in the earths geomagnetic field. A secondary issue is that the strength of the solar wind interaction determines the temperature and hence the rate of the pressure/density decline with altitude. During periods of high activity the pressure of the earths atmosphere that objects in low earth orbit encounter is higher, so drag forces and orbital lifetimes are affected.

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