Radiation in space poses threats for both astronauts and electronic equipment. While it is relatively easy to shield against non-ionizing RF and microwave radiation, shielding against higher energy ionizing radiation – gamma rays, protons, neutrons and galactic cosmic radiation (GCR) – is much more challenging. With longer missions to Jupiter or future manned missions and with the use of smaller spacecraft that cannot accommodate additional weight needed for shielding, the importance of lightweight shielding to NASA has increased. Radiation shielding approaches that have been considered through prior work include fabricating spacecraft out of hydrogen-rich radiation absorbing and scattering plastics instead of aluminum, placing external liquid hydrogen fuel and internal supply water around astronauts as radiation absorbers, and creating strong electromagnetic fields to deflect the radiation. To be effective, however, conventional shielding materials need to be thick and material thickness increases the total unwanted mass to be carried by a small satellite, and the amount of power required to create a deflection field would require significant fuel. NanoSonic proposes to develop lightweight composites consisting of multiple layers of graded atomic number (Z-number) materials as effective ionizing radiation shields beyond Low Earth Orbit. NanoSonic shall advance the Technology Readiness Level to 3 – 5 during Phase I. The composites could be used as the structural shells and support members of small satellites so serve multiple purposes. Preliminary research results with NanoSonic’s materials in the Department of Environmental and Radiological Health Sciences at Colorado State University, and at the NASA Space Radiation Laboratory at the Brookhaven National Laboratory, have shown that our materials significantly attenuate X-rays and gamma rays without secondary radiation, and structurally survive simulated 50-year exposure to solar energetic particles and GCR.
This program would develop a lightweight radiation shielding composite. We foresee integration with future spacecraft as a path to market our materials on a much larger scale. These radiation shielding composites offer enhanced safety and reliability for space structures as they include components for moderate protection against galactic cosmic radiation (GCR), solar energetic particles (SEP), and secondary neutrons. This radiation shielding methodology could represent a large market to improve virtually any existing spacecraft shielding needs.
Similar, multifunctional nanocomposite shielding materials are being developed for other applications by NanoSonic building on our Metal Rubber family of materials, in the 1) electronics, 2) aerospace and defense, and 3) biomedical engineering areas. We foresee integration with current commercial partners such as Lockheed Martin and others as a path to market our materials on a much larger scale.