Description: Radiation from GCRs and Solar Flares provide a hostile ionizing environment for personnel and vital electronic systems. The effects of this environment has been a topic of research for many years. Issues include the exposure for humans under acute and continuous exposures and the radiogenic cancer risk that rises with total dose and is a limiting constraint on long-duration missions. The proposed metal alloy development produces a material that is multi-functional and light-weight for deep space missions. The target material has a significant reduction in mass and potentially volume for protective performance such as radiation and debris shielding applications as well as potential performance thermally and acoustically. Development of these new Mg alloys will improve the margin and overall risk associated with each of these scenarios by improving the shielding performance and provides a reduction in the likelihood of electronic component failure occurrence as well as a reduction in consequence. Equally important, this will reduce the risk of cancer to personnel from radiation exposure. With respect to electronic systems, the systems that provide life support and are considered critical systems are vulnerable to the ionizing radiation effects as well. Once the "heavy" particles penetrate the electronic components, shorts are created in worst case conditions and provide temporary upsets in the best conditions. Similarly, those electronic systems that are considered non-critical, similar effects are seen but have consequences that effect the mission assurance aspects. By replacing existing metallic components with appropriate Mg alloys, such as the ones from this project, both vehicle weight and crew dose rate can be reduced. The operational benefits of such a change are manifold. For example, weight can be replaced with fuel to achieve greater vehicle velocity. Alternatively, mission duration could be extended while operating within equivalent dose limits.

Benefits: This project provides a better alternative to continue along the path for improved multi-functional light-weight Mg alloys. The new metal alloy will improve both NASA Safety and Mission Assurance by offering better protection for the astronauts as well as improving shielding effectiveness of both critical and non-critical electronic systems. For both human and electronic scenarios, the new Mg alloy will improve the margin and overall risk associated with each of these scenarios by improving the shielding performance and provides a reduction in the likelihood of occurrence as well as respective consequence. Specific NASA deployment includes deep space mobile (as well as ISS) habitats, crew spacecraft (Organically and Commercial Crew developed), Mars/Moon fixed habitats, unmanned spacecraft, and launch vehicle/propulsion systems. Such changes may make a manned mission to Mars more feasible. The Lunar Reconnaissance Orbiter (LRO) Cosmic Ray Telescope for the Effects of Radiation (CRaTER) study showed that in interplanetary space the time to a 3% risk of exposure-induced death (REID), the NASA career cancer risk limit would be reached in under 400 days for a 30-year old male and under 300 days for a 30-year old female. The LRO study assumed a thin aluminum alloy layer under the shielding that was tested. If the aluminum were changed to Mg alloys used in this project, it is possible that those calculations could be extended.

This project models and developed multi-functional lightweight Mg alloys, with optimal thickness and chemistry for increasing strength and absorbing neutrons. With the recent approval by the Federal Aviation Administration (FAA) for Mg use in commercial airliner seats (i.e., nonstructural applications), widespread adoption of Mg would allow for high-efficiency aircraft, which could be transformational for the transportation sector. The doped Mg materials that were investigated in this project could be used for reducing the atmospheric radiation exposure of commercial flight crews and passengers on terrestrial polar flights where exposure to radiation has been shown to be significantly higher than on other routes.