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.
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