Pourable and Destroyable Cosmic Ray Radiation Shield for Spacecraft

Abstract

Historically, materials such as lead, tungsten, and iron have been used in spacecraft to shield scientific detectors from Cosmic Rays. These materials work well when reentry to Earth is not an issue. The typical strategy is to have a controlled descent of the spacecraft or to have extremely limited shielding, if any, due to the NASA requirement that all impacting parts must impact with no greater than 15J of energy. Given the nature of this mission neither a controlled descent nor having no shielding was not an option. This is the issue Wichita State University nuSOL team is facing for its 3U CubeSat demonstrator. The CubeSat will be equipped with scientific equipment with the purpose of detecting solar neutrinos, and the less background noise from Cosmic Rays the better the study will be. Through simulations, density tests, and burn tests, WSU was able to develop an epoxy based shield doped with either iron or tungsten powder. The simulations were conducted by firing electrons, protons, alpha particles, and oxygen and iron nuclei into the shield material with energies ranging from 1MeV until consistent failure rate using Geant4. The standards for these simulations are the base epoxy at 1.15g per cc to solid steel at 8g per cc . Mixing tests have determined for iron, a density of 4g per cc is achievable, which is 53 percent iron by volume. Tungsten epoxy with a density of 7.5g per cc is more easily achieved, and results in 40 percent tungsten by volume. These ratios are concrete in texture, pourable, and homogeneous.