Polymer/carbon nanotube composites including single-wall or multi-wall carbon nanotubes incorporated into the matrix of a polymer are provided. These composites can be used in environments exposed to galactic cosmic radiation. Accordingly, the composites are useful in deep space applications like space vehicles, space stations, personal equipment as well as applications in the biomedical arts and atom splitting research. The composites can be modified with organic dyes containing at least one phenyl ring and the resulting doped composite is useful as a radiation detector. The preferred polymer is poly(4-methyl-1-pentene). At low nanotube concentrations (i.e., about 0.5 wt % or less), the composites exhibit transparent optical qualities. At higher nanotube concentrations (i.e., about 0.6 wt % or more), the composites are non-transparent.