Issues in deep space radiation protection

The exposures in deep space are largely from the Galactic Cosmic Rays (GCR) for which there is as yet little biological experience. Mounting evidence indicates that conventional linear energy transfer (LET) defined protection quantities (quality factors) may not be appropriate for GCR ions. The avai lable biological data indicates that aluminum alloy structures may generate inherently unhealthy internal spacecraft environments in the thickness ran ge for space applications. Methods for optimization of spacecraft shielding and the associated role of materials selection are discussed. One material which may prove to be an improtant radiation protection material is hydrog enated carbon nanofibers. (C) 2001 Elsevier Science Ltd. All rights reserve d.