Authors: NASA JSC SRAG
The Space Radiation Analysis Group at NASA Johnson Space Center has prepared a tutorial about the risks to astronaut health due to radiation exposure from Solar Energetic Particle (SEP) events. The presentation is intended to be a useful reference for the operations and research community and will be publicly available at https://srag.jsc.nasa.gov (soon). When discussing space weather, researchers often state that SEP events have the potential to kill astronauts, but is this a reasonable assumption? This presentation first describes how radiation dose is calculated, clarifying the different methodologies and units. A discussion of the radiation-related health effects follows. Lastly, a study of radiation dose and health outcomes for a variety of SEP event and shielding scenarios is presented. The study will explore how SEP events ranging from typical to extreme would impact an astronaut in free space in a thickly shielded vehicle like Orion, a thinly shielded vehicle similar to a space station module, and in nothing but a space suit. Lunar scenarios in a lunar base or lunar EVA are also explored. Finally, calculations will be performed to identify the necessary SEP intensity levels to exceed career limits, to cause acute radiation sickness, and to cause death. The SEP events that will be used for the study include:
May 2024 Gannon Storm (most recently publicized event due to strong geomagnetic component)
March 7, 2012 (most intense event of SC 24)
October – November 1989 series of storms (SRAG’s design reference event)
August 1972 King event (most attributed to have likely caused radiation sickness or death)
Summary slides containing key points:
Slides 1 – 10: Overview of radiation quantities, units, and uses
Slides 54 – 56: Visualization of why numerical values calculated using different methodologies are not comparable
Slides 59 – 60: Key takeaways about radiation dose values and NASA limits
Slides 71 – 81: Dose values used to evaluate likely health impacts from SEP + shielding scenarios
Slides 82-83: Key takeaways about radiation impacts to health
Slides 84 – 107: Study of 4 SEP events with different shielding scenarios showing likely health outcomes, including an evaluation of what it would take to achieve lethality.
Slide 108: Summary of health risks
Slide 109: Why SEP forecasting and radiation protection is relevant and important.