radiation sheilding

[GreylockDS2]

A few pages i have been reading as of late have covered it, but i am curious about the input of this community. Cosmic radiation is a big deal in us going to space , prolonged contact form the background radiation , to solar flares and the surges of radiation that produces.

Most of the sources i have read so far talk about using different materials in the hull of the ships to help block radiation , and even in some cases bunkers on board for the times of extreme radiation form a solar flare.

I am curious would it be practical to have a large electromagnet on the ship to sorta emulate the magnetic field that the earth provides to block the cosmic radiation. Or would the power needed to use it as a shield be impractical, or would having such a shield centralized on a ship disrupt electronics on the ship. Perhaps there is a lot more flaws that i am not seeing.

[Simon_Jester]

Very, very impractical.

The Earth's magnetic field is only marginally helpful in stopping radiation- atmosphere counts for more. It works because it's big: thousands and thousands of miles deep, so even a weak magnetic effect on incoming cosmic rays adds up over long distances. A spacecraft with non-ridiculous power supplies and size couldn't create a field over such a large volume.

An intense enough field to matter over short distances would totally screw over electronics, as you suspected.

You're much better off just piling up stuff in the path of incoming cosmic rays.

[GreylockDS2]

is there any other way of blocking the cosmic rays other then just piling stuff in its path. ?

[Simon_Jester]

Not really. I mean, you might be able to rig up something wonky and complicated, but it'd be far more failure-prone and a lot heavier than just piling graphite and lead on.

Radiation in space isn't actually that big of a problem. It's an issue for something the size of an Apollo capsule because there's no good place to take shelter, but if you're looking at serious designs for interplanetary spacecraft in the tens or hundreds of tons, putting in a well-shielded compartment that can handle radiation hazards becomes pretty easy.

[dragon]

Very, very impractical.

The Earth's magnetic field is only marginally helpful in stopping radiation- atmosphere counts for more. It works because it's big: thousands and thousands of miles deep, so even a weak magnetic effect on incoming cosmic rays adds up over long distances. A spacecraft with non-ridiculous power supplies and size couldn't create a field over such a large volume.

An intense enough field to matter over short distances would totally screw over electronics, as you suspected.

You're much better off just piling up stuff in the path of incoming cosmic rays.

Not quite scientist now say a 100m to 200m buble would be sufficent and require only 1 Tesla.

A team of physicists from the UK, Portugal and Sweden led by Ruth Bamford of the Rutherford lab has shown that it should be possible to shield spacecraft using artificial magnetospheres. Like the real thing, these would separate out the electrons and protons of the solar wind, generating a separation of charge in space that would deflect these particles away from the spacecraft.

snip
Bamford and colleagues say these results show that a spacecraft could in fact be protected using a bubble just some 100–200 m across. This, they say, would correspond to a magnet of about 1 Tesla, which would be light enough to be transported into space.

link

Deflector shields made of ionized gas are under development by British scientists. These Star Trek-style shields could be turned off or on depending on solar activity or other requirements.

Astronauts who spend time in low earth orbit are mostly protected from radiation by the magnetosphere, Earth's powerful magnetic field. However, travelers to other planets will run the risk of exposure to cancer-causing radiation from the sun and other sources outside the solar system.

According to Dr. Ruth Bamford, of the Rutherford Appleton Laboratory in Didcot, UK: "You don't need much of a magnetic field to hold off the solar wind. You could produce the shield 20-30 kilometers away from the spacecraft."

She presented the idea today at the Royal Astronomical Society National Astronomy Meeting in Preston, England. Researchers intend to create the "deflector shield" by generating a magnetic field and then filling the space around the craft with ionized gas. The magnetic field would hold the plasma in place. The same technique could be used to protect an installation on the Moon (which has no magnetosphere like the Earth's).

link

Theres quite a few more. While researching radiation protection for my Masters I found dozens of ways that are being developed or might be someday.
noticed how the newer article dropped the distance.

[Simon_Jester]

It's physically possible, I know- but... well. If I'm wrong about the weight requirements then I'm simply wrong, but do you know of any sources for this that aren't Popular Science-type magazines? There's a tendency to play up technologies like this without bothering to talk about the feasibility.

I think the real thing Greylock should take away from this is that it's a solvable problem- using physical mass of radiation shielding works, there's no urgent need to develop something 'better' although it might be nice if you could make it lighter than the level of radiation shielding otherwise needed- which might be something as simple as a single compartment with a big plate of graphite on one side, which can be rotated to have the plate facing the sun in a pinch.

[dragon]

oh yeah they would need some sort of nuclear power at the least.
But we know how much the anti nuke crowds would love that.

But might would be about the only way to get the power required. Or really huge solar panels

[Rabid]

Or really huge solar panels

Since we're already here... Have solar panels already been used to double as radiators in spacecrafts yet ?

[Sea Skimmer]

The thing to keep in mind is a spacecraft needs shielding against both radiation and debris impacts, and ideally the same system to protect against both. NASA has been studying Polyethylene based compounds for this purpose; while it’s a plastic it works well as shielding because of its high hydrogen content and adding fibers can make it excellent ballistic protection. Magnetic shields might work, but naturally they only provide one half of the protection you need and that's going to work against them heavily in benefit to weight ratio. It’s also doubtful they can ever fully cope with solar particles which significant mass just like the fast neutrons from a nuclear weapon, magentic fields can slow them down but stopping them is probably always going to take physical material.

You’ll probably always need some kind of bunker for radiation buried inside the fuel tanks or some such setup; but the less often you need to use it the smaller and less habitable it can be, and thus lighter.