Spacecraft are self-contained biospheres that must be designed to protect astronauts from harmful aspects of the interplanetary environment. Radiation encountered in deep space poses a significant threat to the health of astronauts and the success of future NASA missions beyond low-Earth orbit. Isotropic galactic cosmic rays (GCRs) and intermittent solar particle events (SPEs) threaten to cause acute radiation sickness and exceed NASA's permissible exposure limits for cancer risk for explorers in near-term space operations. Thus, effective methods of mitigating this radiation risk are high priorities for long-duration space flight. This experiment proposed to design a magnetic shielding architecture capable of reducing the amount of radiation by a factor of four to alleviate many biological uncertainties associated with this risk in the astronaut habitat. Through computational modeling, the spectra of harmful radiation was investigated and lead to the design of a “swarm-bot” type magnetic field configuration that deflected incoming radiation, thus forming a “safe-region” within the astronaut habitat. The novel method proposed here will work in concert with many aspects of existing superconductor technology. This system operates in parallel with the existing NASA Orion spacecraft infrastructure and in a continuous mode but without the need for continuous power.
Investigators previously studied unexplored architecture for a radiation-protected deep space expedition. The Orion spacecraft itself will not be altered. Instead, a number of relatively small independent mobile satellites, each containing superconducting coils, will form a protective array around the spaceship. These satellites will act as magnetic lenses whose purpose is to reduce the radiation flux passing through the volume occupied by the spaceship, thus limiting crew exposure. The magnet array will be reconfigurable and its formation will exploit the principles of swarm-bot technology. Protection against both isotropic GCRs and late-phase SPEs require an evenly spherical magnetic shield which can be created by an array of magnets in a form of a regular polyhedron. The goal of the magnet array is to provide a safe region around the spacecraft in which the number density of the charged particles is lower than it would be in the absence of such a shield. Since magnetic fields do not change GCR and SPE particle energy, the dose of radiation absorbed by the biological tissue inside the protected region is reduced by the same proportion as the number density of the particles. This protection will also provide improved constraints for future models of biological responses to radiation and reduce uncertainties in studies of radiation effects.
The investigators built an infrastructure of robust particle tracking simulations of 10^4-10^5 particles that create an isotropic flux of high order. This infrastructure can build evenly symmetric shields comprised of numerous dispersed magnetic dipoles. They have completed scaled-down, low energy (0.01 MeV) simulations showing that a dispersed 20-dipole shield at 50 m radius can successfully deflect significant isotropic radiation from a 10 m radius central volume (i.e., spacecraft). Despite the scaled-down energies and spatial scale, the code infrastructure is promising in showing that it is indeed feasible to shield a central volume from an isotropic particle flux using a dispersed magnetic shield.