Radiation – Protection and Mitigation
Future NASA human exploration missions to Mars or other distant destinations are some of the key elements of NASA’s strategic roadmap. While several risks identified by the Human Research Program are successfully mitigated, the impacts of health risks due to space ionizing radiation is an unresolved aspect of our Journey to Mars.
The significance of the space radiation health risks manifests most profoundly in the limitation on the maximum duration of exploration missions. The quantification of space radiation health risks relies heavily on modeling, both for the external radiation environment and the passage of external radiation to the inside of crewed vehicles. The datasets used to create and optimize these models are coarse and sparse, causing significant uncertainties in model predictions. Following the ALARA principle, these uncertainties are accounted for in mission planning which effectively reduces the maximum permissible mission durations. This conservatism, however, results in a conflict with required minimum mission durations from trajectory dynamics and science objectives.
Uncertainties on health risk projections can be reduced by collecting new precise data of the radiation environment internal and external to crewed vehicles. The new data enables high-precision comparisons between the modeled/predicted and the actual radiation environment which in turn enables improvement of space radiation environment and transport models and reduction of uncertainties of model predictions.
This innovation challenge topic seeks to complement and support NASA’s current investments in radiation detection technologies by leveraging on external resources to identify and develop precision radiation detectors. Desired radiation detectors and capabilities include the following two categories:
1) Compact/miniaturized neutron spectrometer, to measure time-resolved neutron energy flux spectrum between 0.5 and 200 MeV, with 20% energy resolution above 8 MeV, for IV use in crewed vehicles;
2) Compact/miniaturized charged particle spectrometer, to measure time-resolved directional proton, helium and heavier ion (with charge resolution ΔZ = 2) energy flux spectra, from 50 MeV/n to 500 MeV/n, with 10% energy resolution, for use on unmanned satellites or IV/EV crewed vehicles.
In addition, potential space radiation health effects during or post mission could be controlled and/or mitigated by novel pharmaceutical agents administered pre-, post- or chronically during exposure. Specifically, high priority agents include those which target pathways effecting DNA damage and repair, carcinogenesis, ischemic heart disease, inflammation, neurodegenerative pathologies and cataractogenesis. It is important that these pharmaceutical countermeasures are cross-evaluated to avoid potential negative off-target effects between health risks.
This challenge also includes a call for research results and pharmaceutical agents which support the control or mitigation of space radiation health risks.