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# Cosmic Ray Shield

Copy the Earth's method; use a giant magnetic field
 (0) [vote for, against]

I first had this Idea many years ago, but seldom thought of it, and was reminded of it by the linked Idea.

The Earth has a HUGE magnetic field that protects the biosphere from many cosmic rays. Not all of them, but many. Logically, a space-ship should have the same, if it can.

How?

Well, suppose we build the ship as a hollow cylinder, about as wide as it is tall, and make the walls of that cylinder thick enough to hold all the crew and supply compartments. That gives us two walls, one on the outside of the cylinder, and one on the inside. I have an earlier-posted aircraft-body idea (linked) that is not hugely dissimilar from this one, so refer to it for a better picture. (The linked page has a linked picture, with a description that likely deserves to be [marked-for-tagline]: "I can see it, and I *still* don't believe it!") This spaceship cylinder, though, is a LOT larger than the aircraft body. Please keep that in mind.

We actually want to double-up on those walls. What we now do is make sure those walls are thoroughly insulated, and lower their temperatures so they become superconductive. The next paragraph concerns the outermost and innermost walls, with respect to the overall cylindrical spaceship.

We can now generate a very powerful magnetic field, using the spaceship walls as a giant "single-turn coil". The strongest part of the magnetic field is in the hollow of the cylinder.

The inner parts of the doubled walls are also superconductive, but we don't run a current through them. They exist to prevent the magnetic field generated by the outer walls from penetrating and causing problems in the crew and storage compartments.

Per the Inverse-Square Law, the farther away from the spaceship, the weaker its magnetic field will be. Also, the stronger the magnetic field AT the spaceship, the huger will be the overall magnetic field, in terms of being able to affect cosmic rays.

If the overall field is large enough, the path of those charged particles will TEND to be curved such that they pass through the hollow of the cylindrical spaceship, completely bypassing the crew and storage compartments.

 — Vernon, May 29 2015

Reminding Idea Cosmic_20ray_20protection
As mentioned in the main text. [Vernon, May 29 2015]

Cylindrical aircraft body Cylindrical_20Aircraft_20Body
As mentioned in the main text. [Vernon, May 29 2015]

 Actually, I think you want to power inner and outer coils. If the same current is in both in the same direction, the net magnetic field between them will be close to 0. If the width of the passenger compartment is small in relation to the diameter of the cylinder fields can cancel very well. As the curvature is greater in comparison to the size, the field will be stronger, the magnetic field will increase near the inner and outer walls.

An unpowered superconductor would act as a Faraday cage with doesn't stop static magnetic fields. A steal box can shield it's contents from a magnetic field, but it would surely saturate at the levels that we're talking about. Then again, some ferromagnetic shielding might be just the thing to get rid of or reduce the uneven uneven magnetic filed between the inner and outer walls.
 — scad mientist, May 29 2015

 [scad mientist], I specified using 2 sets of walls partly because I was unsure about there being zero field inside the "outer" wall. Also, I think you are misinterpreting something (but easy to do without a diagram). Here's an ASCII sketch representing the description in the main text: //=\\ . . . . . //=\\ ||=|| . . . . . ||=|| ||=|| . . . . . ||=|| ||=|| . . . . . ||=|| ||=|| . . . . . ||=|| \\=// . . . . . . \\=// The = signs represent the crew and storage compartment regions of the cylinder. The dots occupying the interior hollow of the overall cylinder should be ignored; they are only there so space the cylinder walls apart. The leftmost and rightmost vertical bars are the SAME outermost wall of the overall cylinder. The vertical bars adjacent to the dots are the SAME innermost wall of the overall cylinder.

 While not specifically stated in the main text, a cylinder has an END-edge, which in this case is implied by the various slash characters. The innermost and outermost walls connect at the top and bottom of the cylinder (not portrayed).

 In the main text is the phrase, "the inner parts of the doubled walls", and you can see it in the above sketch as the vertical bars NOT previously described here. These walls are, electrically speaking, entirely separate from the outermost and innermost walls (but also connect near the top and bottom of the overall cylinder.)

 Now here is an ASCII sketch of an alternative, missing the "inner parts of the doubled walls": /=\ . . . . . /=\ |=| . . . . . |=| |=| . . . . . |=| |=| . . . . . |=| |=| . . . . . |=| \=/ . . . . . \=/

If all the current flows in the wall, and there is no magnetic field inside the wall, where the crew and storage compartments are, then there is simply no need for the doubled walls previously mentioned. But if there IS an interior magnetic field, the occupants of the spaceship need to be protected from it, and that is what the extra walls are for (as specified in the main text).
 — Vernon, May 29 2015

I believe the Borg have a similar solution, but it's merely a double-wall outside the hull, packed with cats.
 — not_morrison_rm, May 29 2015

 Very, very tightly packed ... and open to vacuum.

 //The Earth has a HUGE magnetic field that protects the biosphere from many cosmic rays. Not all of them, but many. //

That depends on the definition of a "cosmic ray". Most are highly energetic gamma rays which aren't deflected by magnetic fields.
 — 8th of 7, May 29 2015

 Shirley that would lower the efficacy? As cats contain water. Removing the water would lower the numbers of atoms between you and cosmic rays....

Alternatively, the less water the the cats contain the lower the chance of hits by a gamma rays turning one of them green, angry and very large, then using the outside of the warp drive as a scratching post, leading to the...usual consequences.
 — not_morrison_rm, May 29 2015

If any of this is possible where is the vast amount of power going to come from to make it work? From the cosmic rays themselves?
 — cudgel, May 29 2015

 Would it not be better to do this electrostatically? A charged mesh around the ship should either deflect cosmic rays away, or pull them onto the mesh (depending on charges).

I suspect that you could maintain an extremely high charge on a mesh (which could be deployed some distance from the ship) with very very little energy cost, and with much less mass than either permanent or electromagnets.
 — MaxwellBuchanan, May 29 2015

Any charge you need on this mesh would presumably come as a by-product of the spacecraft's ion drive.
 — hippo, May 29 2015

One very obscure sf book, "Jupiter Thieves" (from memory), some pesky aliens make off with Jupiter as a shield against this kind of stuff and other nasties when travelling very quick around the universe..
 — not_morrison_rm, May 29 2015

Okay, I misread the superconductors to be between the walls. As I said, the magnetic field in the crew compartment will be fairly small without the extra layer of superconductors, but on further consideration my statement that a Faraday cage doesn't block static magnetic fields was actually incorrect when applied to a superconducting Faraday cage. In a copper Faraday cage a magnet approaching will induce an eddy current that will soon go away due to resistance. An eddy current in a superconducting Faraday cage will keep going. But if the field is small enough without it, you could save weight by leaving it out.
 — scad mientist, May 29 2015

 Vernon I may have vaguely remembered your concept in putting together mine. I think astronauts would be safe inside a giant, turned on MRI. I thought the power requirements would be impractical so made it many tiny MRI-like coils, which would in fact be powered by the charged particles themselves as cudgel proposed.

Still looking for some math for that other idea. Supercat? Lurch?
 — bungston, May 29 2015

 //How would we know that hasn’t actually happened, and here’s where they hid it?

One way to tell, see if it still has the "Planet Jupiter: Packed by weight, not volume. Contents may settle in transit" sticker just above the red spot.
 — not_morrison_rm, May 29 2015

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