# How much power would a space craft's magnetic shield require? [closed]

I've read over the decades that a magnetic shield might protect a spacecraft from cosmic radiation. Its a fascinating idea that might only be theory or science fiction at the moment. In regards to that here is an article just in case someone isn't sure what I mean:

http://physicsworld.com/cws/article/news/2008/nov/06/magnetic-shield-could-protect-spacecraft

The article even mentions simulations about midway into the article. Does anyone know if research has continued?

My big question though, is how much electrical power would be required to protect a space vessel in this way? How large would the field be in order to be useful?

Better yet, please use some practical objects that anyone can wrap their head around: What if you were using similar technology to protect the Apollo Command Module? Or the Discovery One from 2001 (140 meters long).

In laymans terms, how much electrical power would it take to create a magnetic shield?

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## closed as off-topic by jinawee, Kyle Kanos, centralcharge, Brandon Enright, Qmechanic♦Feb 19 '14 at 14:59

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The link you provide gives a link to the relevant paper on Plasma Phys. Control. Fusion, which you can then click the "Cited By" tab and see only 4 papers referencing that one, the latest in 2012. I am unsure if the work is stalled or if it's just not cited anymore because it's outdated. – Kyle Kanos Feb 17 '14 at 15:43
If superconductors were used, once you got them up to full field strength maintaining them should take little or no more power. I'm not sure how they'd be cooled though. Radiation to space is terribly slow. – Brandon Enright Feb 17 '14 at 16:45
What if there weren't any superconductors? – Maelish Feb 18 '14 at 2:11
While it might be an engineering question, I'll grant you that. There is no other forum on stack exchange that covers this type of question. Unless perhaps you mean the Space Exploration Beta? I could cross post there. – Maelish Feb 21 '14 at 3:36

## 1 Answer

If it is a supercon magnet, it runs without losses until the field is deformed by a solar coronal mass ejection blasting by. It offers no protection against energetic photons.

Consider a one tesla field filling a 200 m diameter bubble. How many joules is 4.2 million m^3 of one tesla field? (Suppose the field collapsed into a solenoid shorted by a resistor.) A quench would be messy. Photosynthesis and mammalian metabolism both go through free radical intermediates. A one tesla field polarizes unpaired spins parallel, a triplet sate, preventing bonding or certainly slowing its kinetics. An hour in an MRI tunnel is not six months. Metabolic discrepancies will accumulate.

$1 T = 1 \mathrm{N{\cdot}s{\cdot}C^{-1}{\cdot}m^{-1}}$
${PV = energy}$, 101.325 J/liter-atm

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I don't really understand the math. Sorry, can you tell me in laymans terms please? – Maelish Feb 18 '14 at 2:11
The inflated magnetic field contains a HUGE amount of energy. If it suddenly collapses, power = energy/time. Shine a one watt light into your face for an hour, no biggie. Flash a 36 kilowatt light into your face for a tenth second, biggie. The field stressed by a solar burp warms the supercon solenoid and stresses its windings (Lorentz force). If one winding goes normal, BOOM! – Uncle Al Feb 18 '14 at 4:23
But how much power or electricity would it take to generate a field in the first place? Based on the 2 sizes I have asked about? – Maelish Feb 18 '14 at 14:41