Spacecraft shield
A spacecraft and spacesuit having a radiation shield are disclosed. The shield comprises a hydrogen-containing material encapsulated or bound in a polymer. The hydrogen-containing material has a higher hydrogen content than polyethylene. The hydrogen-containing material may be: encapsulated in a polymer container, sandwiched between layers of polymer, mixed with a polymer as binder, or held in the pores of a polymer foam. The hydrogen may be a hydride or borohydride such as beryllium borohydride, ammonium octahydrotriborate, lithium borohydride tetramethyl ammonium borohydride and beryllium hydride. Methods of manufacturing the shield are also disclosed.
1. A radiation shield characterised by comprising a hydride and a thermoplastic or thermosetting polymer binder wherein the radiation shield comprises greater than 14.4 wt % hydrogen.
2. A radiation shield as claimed in claim 1 characterised in that the hydride is selected from one or more of ammonia borane, ammonium borohydride, methylammonium borohydride, an ammoniate of lithium borohydride, a methyl amine borane, ammonia triborane, ammonium octahydrotriborane, lithium borohydride and beryllium hydride.
3. A radiation shield as claimed in claim 1 characterised in that the polymer binder is one or more of polyethylene, polypropylene, polyisobutylene, polybutadiene, poly(methyl methacrylate), polysulphone, polystyrene, poly(vinyl pyrrolidone), poly(vinylidene fluoride), poly(tetrafluoromethylene), polyethylene oxide, poly(vinyl acetate), polyester, a co-polymer comprising two or more polymers, polyepoxide, polyimide, polyamide, polyaramide and melamine formaldehyde.
4. A radiation shield as claimed in claim 1 characterised in that the polymer binder is one or more of polyethylene, polypropylene, poly(4-methyl-1-pente), nylon6,6, poly(vinyl alcohol) and poly(oxymethylene).
5. A radiation shield as claimed in claim 1 characterised in that the hydride has a hydrogen content in the range 14 to 25 wt %.
6. A radiation shield as claimed in claim 1 characterised in that it is prepared by polymerising a monomer corresponding to the polymer binder in the presence of the hydride and a polymerisation catalyst.
7. A radiation shield as claimed in claim 1 characterised in that it is prepared by mixing the polymer binder and the hydride before moulding.
8. A radiation shield as claimed in claim 6 characterised in that preparation is carried out in the presence of a solvent.
9. A radiation shield as claimed in claim 1 characterised by comprising a composite of alternating layers of polymer binder and hydride.
10. A radiation shield as claimed in claim 1 characterised by comprising a flexible film of the polymer binder and hydride.
11. A radiation shield as claimed in claim 1 characterised by a mat of fibres comprising the polymer binder and the hydride.
12. A radiation shield as claimed in claim 1 characterised by comprising the hydride held in the pores of a foam of the polymer binder.
13. A radiation shield as claimed in claim 1 characterised by comprising a solid block prepared by sintering a mixture of the thermoplastic polymer binder and the hydride at high pressures and high temperatures.
14. A radiation shield as claimed in claim 1 characterised by comprising a mixture of the hydride and polymer binder in a polymer box.
15. A radiation shield as claimed in claim 1 characterised in that the hydride does not melt or release hydrogen at temperatures below 100° C.
16. A radiation shield as claimed in claim 1 characterised by further comprising a polymer layer or metallised polymer layer, said layer being gas impermeable and enveloping the hydride.
17. A radiation shield as claimed in claim 1 characterised in that the radiation shield comprises a neutron absorber, wherein the neutron absorber is one or more of lithium isotopically enriched with lithium-6 and boron isotopically enriched with boron-10.