Dose Predictions for Moon Astronauts Image Source: Nicholas Bachmann, Ian Rittersdorf Nuclear Engineering and Radiological Sciences

Premise <- Abstract?? We will be sending astronauts into space for Lunar and Martian exploration missions. We will be sending astronauts into space for Lunar and Martian exploration missions. The dose given to these astronauts is a big concern to their safety. The dose given to these astronauts is a big concern to their safety.

Cosmic Dose Sources Galactic Cosmic Rays (GCR) Galactic Cosmic Rays (GCR) Solar Energetic Particles (SEP) Solar Energetic Particles (SEP) Intrinsic Lunar Radiation Intrinsic Lunar Radiation Image Source :

Galactic Cosmic Rays Composition: Composition: 85% protons 85% protons 14% alpha particles 14% alpha particles 1% heavy nuclei 1% heavy nuclei Heavy nuclei are very dangerous because of the energy they have (proportional to Z 2 ) Heavy nuclei are very dangerous because of the energy they have (proportional to Z 2 ) Hard to measure precisely. Hard to measure precisely. Current Models are believed to be 25% accurate Current Models are believed to be 25% accurate

Solar Energetic Particles SEPs consist primarily of protons and alpha particles. SEPs consist primarily of protons and alpha particles. Are formed on active surfaces of the sun. Are formed on active surfaces of the sun. Lower energy particles than GCRs Lower energy particles than GCRs Higher flux of particles than GCRs Higher flux of particles than GCRs Image Source:

Solar Flares Solar flares emit considerable amounts of radiation, up to tens of Gy. Solar flares emit considerable amounts of radiation, up to tens of Gy. Between Apollo 16 and 17, one of the largest solar flares ever recorded occurred. If the flare had occurred during a mission — even inside their shielded spacecraft, the astronauts would have absorbed lethal doses within 10 hours. Between Apollo 16 and 17, one of the largest solar flares ever recorded occurred. If the flare had occurred during a mission — even inside their shielded spacecraft, the astronauts would have absorbed lethal doses within 10 hours.

Lunar Thorium Hotspots Because space suits protect well against α/ low energy gamma, Th in the soil is not a major concern Because space suits protect well against α/ low energy gamma, Th in the soil is not a major concern If any kind of space station were constructed on the moon, radon would be a major concern if lunar soil was used in cement If any kind of space station were constructed on the moon, radon would be a major concern if lunar soil was used in cement Image Source:

Apollo Mission Doses No significant difference between

Nuclear Radiation from a Planetary Surface

Effects on Health Worst-case scenario estimates an increase in carcinogenic risk of 45% to interplanetary astronauts. Worst-case scenario estimates an increase in carcinogenic risk of 45% to interplanetary astronauts. NASA/NCRP goal is 3% NASA/NCRP goal is 3% Is difficult to quantify due to the uncertainty in the knowledge of the biological response of to particles of various atomic numbers and energies. Is difficult to quantify due to the uncertainty in the knowledge of the biological response of to particles of various atomic numbers and energies.

Conclusions Elevated or even fatal does to astronauts are possible outside of Low Earth Orbit if proper planning is not done Elevated or even fatal does to astronauts are possible outside of Low Earth Orbit if proper planning is not done Radionuclides in the soil may be a concern for lunar bases Radionuclides in the soil may be a concern for lunar bases Due to longer travel times, potential missions to Mars would have to be ready for solar flares Due to longer travel times, potential missions to Mars would have to be ready for solar flares

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