This paper describes an experimental study of gamma radiation effects in low-density arrays of vertically aligned carbon nanotubes. These arrays are characterized by excellent anti-reflective and absorbing properties for wavelengths from UV to IR which makes them an interesting option for stray light control in optical space applications. Gamma irradiation equivalent to an estimated surface life-time exposition in geostationary orbit does not affect the reflectivity of the structures. First high-energy proton irradiation studies indicate that the reflectivity of the carbon nanotubes forests remains unchanged.