Shielding against Debris and Radiation in Orbit
And exploration into shielding strategies for large structures in LEO

NEAmines group, November 2008
With contributions from Jan Kaliciak (EOS Mars Program, Graphic Design),  Ueli Scheuermeier,  Debi-Lee Wilkinson, James Brown, Shaun Strong

This article is published as a printable document . This is the webpage with the summary

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All illustrations are copyrighted. Permission for their use in any other publication or format must first be sought by contacting Jan Kaliciak at eos.mars.program@btinternet.com
Summary
Specifications for the shielding:
  • Where the crew work inside the garage in their coveralls, radiation levels shall be held equivalent to altitude 4000m on Earth
  • Keep a hit by a piece of junk or meteorite up to the size of a tennisball from breaching the pressure shell. Tennisball, because this is the minimum size that can reasonably be expected to be tracked by ground-based radar
    • <><>Anything bigger than this is not what the shield must manage, as collisions can be predicted and taken care of with evasive manoeuvres of the station, or through hunting the piece with a tug and hauling it in.
  • Anything smaller must not breach the pressure shell.
  • Must not result in a spray of smaller pieces flying off from an impact and contributing to the junk in orbit.
  • This means the shield must ‘swallow and hold’ the incoming debris.
  • Progressive improvement of the shield possible through modular elements added to it.

The shield must have the following four layers with diverse functions:
1  Outer skin
The outer skin must allow incoming projectiles to go right through it in a clear and contained puncture, and then hold in any pieces and debris resulting from the impact. Sizes of projectiles are expected to be from less than 1 mm to 50 mm (tennisball). The pieces that will need to be held will range in size from small chips (1mm) to large chunks from the shielding material getting displaced or cut loose by an impact.
2  Impact layer
This is the main zone where serial impacts through multiple layers of metal foil and refraction from variously dense material with angled surfaces stops the projectiles and brakes down or dissipates the radiation. Furthermore this layer is also the crush-zone for slow collisions. This layer should therefore be as ‘fluffy’ as possible, and thereby may
be as wide as possible. The structure of this layer is open for a lot of fantasy. Apart from materials specifically designed and manufactured for this layer, other materials can also be integrated, such as collected space-junk, waste from operations and
processing, tanks of various liquids, stores, semi-processed materials waiting for further processing, equipment ‘parked’ for later use, etc….
3  Pressure skin
This holds in the atmosphere when the ‘garage’ of LEOstation is under pressure. Again, many solutions can be thought of, ranging from inflatables pressing against ‘chainmail’, foamed structures for stiffening, several skins one within the other with progressively lower pressure towards the outside, metal sheeting, etc…
4  Radiation layer
These are plastics in various forms finally stopping any cosmic or secondary radiation that makes it through to this level.




The full article is 16 pages, 4.7MB, pdf

Download it HERE

The NEAmines group welcomes feedback on these preliminary designs.
We also welcome people who may want to join the effort.
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