CLEAR – All-Clear SEP Forecast: A NASA Space Weather Center of Excellence

CLEAR will deliver capabilities for robust and quantifiable forecasts of the space radiation level of up to 24 hours, in support of aviation, satellites, and space exploration. Solar energetic particles (SEPs) can be accelerated over a wide range of energies extending up to GeVs. At relatively low energies (e.g., ~10 MeV), their flux intensity can exceed the background of galactic cosmic rays by several orders of magnitude. Protons of >100 MeV with elevated fluxes exceeding 1 proton flux unit are responsible for an increased astronaut exposure inside spacecraft shielding. Protons of >150MeV are very difficult to shield against as they can penetrate 20 gm cm (7.4 cm of Al, or 15.5 cm of water/human tissue). Furthermore, > 500 MeV protons can penetrate the atmosphere and pose radiation hazards to aviation. Besides protons, energetic heavy ions, e.g., Fe ions, can be of more severe radiation concerns. SEPs are hazardous not only to humans but also to electronics and other sensitive components in space, affecting satellite operations. The sparsity and high variability in terms of intensity, duration, composition,and energy spectra of SEP events make them difficult to predict. The CLEAR Center will develop, test and validate a self-contained, modular (“plug and play”) framework that includes all major elements impacting SEPs in the inner heliosphere: 4π maps of photospheric magnetic fields, corona (1 − 20Rs), inner and middle heliosphere (0.1 AU to Jupiter’s orbit) plasma environment, magnetic connectivity with respect to the solar source, flare/CME initiation, SEP seed population, flare and shock acceleration, and energetic particle transport. In addition, the framework will be able to accommodate radiation interaction models, which will be used to study the penetration of spacecraft walls, radiation effects on the terrestrial magnetosphere, and the radiation doses received by human tissues.