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Old 06-12-2009, 08:57 PM   #1
Agemegos
 
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Default Radiation shielding

What's the story with radiation shielding on ships and orbital habitats in Traveller? Solar storms, Van Allen belts, and the radiation belts of gas giants are never mentioned as a hazard (that I know of), but I seem to remember something about radiation killing crew in space combat.

Is there a canonical explanation in terms of physical or magnetic shielding? Or are cosmic radiation and radiation belts simply ignored without explicit explanation?
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Old 06-12-2009, 11:21 PM   #2
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Default Re: Radiation shielding

At least according to Striker, even an "unarmored" starship has an armor rating of 40, which was 33 cm of steel equivalent as far as penetration goes. That's about 33 halving thicknesses, depending on what sort of radiation you're talking about, if the material absorbed radiation as well as steel. A ten-billionth of the incident radiation may be negligible for natural causes. And of course the material matters; maybe higher-tech spaceship hull material is better at absorbing radiation than is steel.

The meson weapons would penetrate the armor and then decay inside, so you wouldn't get protection from the hull, hence the radiation casualties. If I recall, the High Guard nukes also has a bonus for calculating casualties due to radiation, but they'd be external.

Nuclear dampers (and enhancers) exist. They were only described as anti-nuke weapons, as I recall, but the same tech might be pressed into service as a radiation "shield" to reduce Bremsstrahlung in the armor.

Higher tech medicine might presumably allow you to better recover from radiation exposure, thus allowing more exposure over long time intervals (as opposed to combat). I don't recall any mention of that in particular, but it could be another reason the routine exposure is neglected.
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Old 06-13-2009, 12:00 AM   #3
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Default Re: Radiation shielding

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Originally Posted by Anaraxes View Post
At least according to Striker, even an "unarmored" starship has an armor rating of 40, which was 33 cm of steel equivalent as far as penetration goes. That's about 33 halving thicknesses, depending on what sort of radiation you're talking about, if the material absorbed radiation as well as steel.
I am immediately concerned with natural-source radiation from solar storms and radiation belts, which means mostly charged particle radiation: beta rays and protons, some high-energy ions.

Quote:
Nuclear dampers (and enhancers) exist. They were only described as anti-nuke weapons, as I recall, but the same tech might be pressed into service as a radiation "shield" to reduce Bremsstrahlung in the armor.
That's the issue with charged particles, isn't it? They aren't very penetrating themselves, but braking radiation when they stop amounts to some pretty hard x-rays.

Quote:
Higher tech medicine might presumably allow you to better recover from radiation exposure, thus allowing more exposure over long time intervals (as opposed to combat). I don't recall any mention of that in particular, but it could be another reason the routine exposure is neglected.
Well, I'm considering radiation levels like those in the radiation belts of a large gas giant like Jupiter. And those will probably kill you too fast for medicine to fix you up, besides which they fry hardware.
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Old 06-13-2009, 01:47 AM   #4
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Default Re: Radiation shielding

AFAIK there is no real discussion of it. VE2 had Radiation Shielding of superscience quality, presumably the OTU has something comparable or even better.
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Old 06-13-2009, 06:46 AM   #5
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Default Re: Radiation shielding

Radiation shielding in Traveller is what I like to call a MacGuffin Technology made from unobtanium and powered by handwavium. Like jump Drives, maneuver drives contra gravity, etc.

It is an example of an essential technology that is required to allow us to tell fascinating adventure stories. The key to using such technology is to limit the effect to just solving the first problem.
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Old 06-13-2009, 08:25 AM   #6
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Default Re: Radiation shielding

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Originally Posted by Brett View Post
What's the story with radiation shielding on ships and orbital habitats in Traveller? Solar storms, Van Allen belts, and the radiation belts of gas giants are never mentioned as a hazard (that I know of), but I seem to remember something about radiation killing crew in space combat.

Is there a canonical explanation in terms of physical or magnetic shielding? Or are cosmic radiation and radiation belts simply ignored without explicit explanation?
They are ignored in CT and (basically) GT.

Cosmic and radiation belt stuff (along with solar storms) are two different sorts of beasts. Shielding against things like Jupiter's radiation belts is thoroughly doable. Transhuman Space basically ignores them except for people in vacc suits and equivalents. Very low penetration.

Cosmic radiation shielding in entirely another matter. Space habitats should have the equivalent of 3 meters of lunar rock (and nothing but mass matters). That 33 cm of steel is nowhere near good enough.

Transhuman Space again just heals this faster with nano than the cosmic radiation can do damage. Canon Traveller has no equivalent.
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Old 06-13-2009, 12:22 PM   #7
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Default Re: Radiation shielding

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Cosmic radiation shielding in entirely another matter. Space habitats should have the equivalent of 3 meters of lunar rock (and nothing but mass matters). That 33 cm of steel is nowhere near good enough.
In itself no, but I've always figured the expense and TL of the hull implied/includes magnetic shielding specifically for this. So you're fine aboard a space ship or small craft. Not aboard a simple vehicle or in a vacc-suit for very long.
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Old 06-13-2009, 12:35 PM   #8
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Default Re: Radiation shielding

I agree canon didn't address the question at all. We're just retrofitting explanations.

Quote:
braking radiation when they stop amounts to some pretty hard x-rays
That depends a lot on the material. Metals are bad in this regard. Polyester and other plastics are a common modern-day suggestion. The Striker terms for armor tend to suggest super-metals ("crystaliron", etc). But even just considered as armor, it's probably layered. I don't think it's much of a stretch to assume there's layers of hydrogen-dense radiation absorption material in the hull -- or even armor of ground vehicles, military or those ATVs and G-Carriers intended to explore planets without the benefit of atmosphere or magnetic fields.

Liquid hydrogen is also pretty good radiation shielding in this regard. Traveller ships certainly haul around vast quantities of the stuff. (We finally know why! It's flushed into jumpspace to get rid of the isotopes with induced radiation :)) Most of the deck plans put the fuel conformally along the hull, which is convenient for this bit of handwaving.

There's not much to hint at magnetic or electrostatic shielding. Sandcaster sand gets carried along by gravitic tech. (Didn't Traveller 2300 ships have emag shields suspending ablative particles? But that's not really Traveller anyway.)

Quote:
the equivalent of 3 meters of lunar rock
Google isn't giving me any convenient numbers for lunar rock. Concrete has a halving thickness of about 6 cm, so 500 halving-thicknesses or a High Guard armor factor of 4 (Striker 72, 538 cm steel equivalent). Assuming, again, that the superscience armor shields against radiation proportionately. The armor factors are really about penetration.

It occurs to me that most of the crew's time in spent in jumpspace. They're only exposed to cosmic rays during the transition to and from the 100D limit. Then they spend another week on the ground arranging for cargo (and having adventures) So the annual exposure might actually not be that high. Military vessels, on the other hand, presumably spend a lot more of their time sitting around in normal space with at least one shift of crew on board. The garrisons and patrol cruisers will have a concern.
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Old 06-13-2009, 12:45 PM   #9
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Default Re: Radiation shielding

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It occurs to me that most of the crew's time in spent in jumpspace. They're only exposed to cosmic rays during the transition to and from the 100D limit.
Except when they decide to run to the local gas giant to skim fuel (about a week in normal space for a trader). And all the implied bits about in-system traffic of up to a week travel time (since if it's much longer than a week Jump is faster and then it's a matter of expense/cost evaluation).

And that 100D travel time may also be a week (or longer?) for a world in a close orbit of the larger stars. Earth itself is just outside the 100D of Sol iirc so it's not an issue for Earth, but other systems may well have long real space travel times.

Whatever method is used it can't be good enough to negate weapon radiation damage on it's own. That's the job of extra armor and/or nuclear dampers.
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Old 06-13-2009, 02:31 PM   #10
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Default Re: Radiation shielding

Hey Brett, Thought I'd chime in here being that my background is in Health Physics...


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I am immediately concerned with natural-source radiation from solar storms and radiation belts, which means mostly charged particle radiation: beta rays and protons, some high-energy ions.
The types of radiation in nature are Alpha, Beta and Gamma. Alpha is what your calling protons which is 2 protons and 2 neutron bound together like a helium nucleus, most alpha tends to be short range ejected from the main source... http://en.wikipedia.org/wiki/Alpha_radiation

Alpha radiation is low energy and can be blocked by paper or a layer of dead skin, and is not too penetration.

Beta radiation is medium energy electrons or positrons emitted by radioactive nuclei of most any unstable form of matter.

http://en.wikipedia.org/wiki/Beta_radiation

Beta radiation is penetrating and is in most cases blocked by lead, steel, water or distance. This would and should be the reason for "40 G" starship armor.

The third and last form is Gamma radiation and is the most lethal and dangerous form. Gamma Radiation is high energy Electromagnetic radiation of usually sub-atomic reactions. It is this form of radiation where atomic and sub atomic meet and where energy particles can and do become waves of energy... the more energy, the more likely it is in wave form, the less likely it is a particle. and vice versa.

http://en.wikipedia.org/wiki/Gamma_Radiation

As Wiki states Gamma sources come from many different methods, They are produced by sub-atomic particle interactions, such as electron-positron annihilation, neutral pion decay, radioactive decay, fusion, fission or inverse Compton scattering in astrophysical processes.

In truth the only known forms of protections from Gamma is Time, Distance and Shielding. Time only works in space if you can isolate the source and then put distance between you and it so that it can decay. Distance works well for stationary sources, and Shielding is usable where large masses can stand between you and the source protecting you from the full strength of the source.

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Originally Posted by Brett View Post
That's the issue with charged particles, isn't it? They aren't very penetrating themselves, but braking radiation when they stop amounts to some pretty hard x-rays.
Correct, when I went to school they had a film of particles hitting a wall of a radiation containment and putting off x-rays... this was one way of proving and showing that radiation existed in the areas around the containment.


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Originally Posted by Brett View Post
Well, I'm considering radiation levels like those in the radiation belts of a large gas giant like Jupiter. And those will probably kill you too fast for medicine to fix you up, besides which they fry hardware.
Correct again, the only true methods in these areas will be to use robots, waldos and probes... and then special shielding will have to be created to protected these devices to even allow them to function...

Hope this helps some...
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Last edited by Voidstar; 06-13-2009 at 02:35 PM. Reason: submitted too early
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