BOUNDING-CASE RADIATION ENVIRONMENT MODEL FOR SHORT CREWED MISSIONS

Abstract:

We have applied a data-driven approach to develop a probabilistic model for solar energetic

particle fluences during missions lasting up to ten days. This model provides bounding-case

fluence spectra for protons and helium which may be used as an alternative Design Reference

Environment (DRE) for mission design and planning. Previously NASA adopted the Band

function fitting of the series of event occurred on1989-10-19 as the standard DRE, and provided

it to their partners in the US aerospace industry guiding the development of next generation

crewed spacecraft. The probabilistic model can generate a sequence of event spectra that

depend on user supplied mission duration (< 10 days), an approximate sun spot number, and

different confidence levels. The details of the model and the data on which it is based will be

described. The application of a DRE will be demonstrated to NASA’s Artemis program which

seeks to land astronauts on the moon again very soon. The final leg of the mission will launch

from a Lunar Gateway station in near lunar orbit, and a lunar landing vehicle will transport

the crew between the Gateway and the lunar surface on missions lasting up to 10 days. The

calculation of crew dose using the DRE will be demonstrated for a notional lander design. This

model will be used to insure the proposed lander designs provide adequate shielding to limit

crew doses even in the worst-case environment.