Patent Number: 
Section: claims

1. A radiation shielding apparatus, comprising:a. an annular cryogenic vessel adjacent a circumferential side wall of a crew module; andb. a cryogenic hydrogen radiation shielding material capable of providing a radiation shield, said cryogenic hydrogen radiation shielding material including hydrogen at a temperature of less than or equal to about 20 K,wherein said cryogenic hydrogen radiation shielding material is contained in said annular cryogenic vessel. 2. The radiation shielding apparatus of claim 1, wherein said cryogenic hydrogen radiation shielding material includes hydrogen at a temperature of less than or equal to about 14 K. 3. The radiation shielding apparatus of claim 1, wherein said cryogenic hydrogen radiation shielding material includes hydrogen at a temperature of less than or equal to about 12 K. 4. The radiation shielding apparatus of claim 1, said cryogenic hydrogen radiation shielding material including hydrogen at a temperature of from about 10 K to about 12 K. 5. The radiation shielding apparatus of claim 1, wherein said cryogenic hydrogen radiation shielding material includes liquid hydrogen, subcooled liquid hydrogen, solid hydrogen, subcooled solid hydrogen or a mixture thereof. 6. The radiation shielding apparatus of claim 1, wherein said cryogenic hydrogen radiation shielding material includes solid hydrogen, subcooled solid hydrogen or a mixture thereof. 7. The radiation shielding apparatus of claim 6, wherein said annular cryogenic vessel includes an aluminum skin and aluminum foam. 8. The radiation shielding apparatus of claim 1, wherein the cryogenic vessel includes at least one connector capable of attaching to a conduit capable of supplying or maintaining the temperature of the cryogenic hydrogen radiation shielding material.