Dose Predictions for Moon Dose Predictions for Moon AstronautsAstronauts

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Nicholas Bachmann, Ian Rittersdorf

Nuclear Engineering and Radiological Sciences

Premise <- Abstract??Premise <- Abstract??

We will be sending astronauts into space We will be sending astronauts into space for Lunar and Martian exploration for Lunar and Martian exploration missions.missions.

The dose given to these astronauts is a The dose given to these astronauts is a big concern to their safety.big concern to their safety.

Cosmic Dose SourcesCosmic Dose Sources

Galactic Cosmic Rays (GCR)Galactic Cosmic Rays (GCR)Solar Energetic Particles (SEP)Solar Energetic Particles (SEP) Intrinsic Lunar RadiationIntrinsic Lunar Radiation

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Galactic Cosmic RaysGalactic Cosmic Rays

Composition:Composition:85% protons85% protons14% alpha particles14% alpha particles1% heavy nuclei1% heavy nuclei

Heavy nuclei are very dangerous because Heavy nuclei are very dangerous because of the energy they have of the energy they have (proportional to Z(proportional to Z22))

Hard to measure precisely.Hard to measure precisely.Current Models are believed to be 25% Current Models are believed to be 25%

accurateaccurate

Solar Energetic ParticlesSolar Energetic Particles

SEPs consist primarily of protons and SEPs consist primarily of protons and alpha particles.alpha particles.

Are formed on active Are formed on active surfaces of the sun.surfaces of the sun.

Lower energy Lower energy particles than GCRsparticles than GCRs

Higher flux of Higher flux of particles than GCRsparticles than GCRs

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Solar FlaresSolar Flares

Solar flares emit considerable amounts of Solar flares emit considerable amounts of radiation, up to tens of Gy.radiation, up to tens of Gy.

Between Apollo 16 and 17 , one of the Between Apollo 16 and 17 , one of the largest solar flares ever recorded largest solar flares ever recorded occurred. If the flare had occurred during a occurred. If the flare had occurred during a mission — even inside their shielded mission — even inside their shielded spacecraft, the astronauts would have spacecraft, the astronauts would have absorbed lethal doses within 10 hours.absorbed lethal doses within 10 hours.

Lunar Thorium HotspotsLunar Thorium Hotspots Because space suits Because space suits

protect well against protect well against αα/ / low energy gamma, Th low energy gamma, Th in the soil is not a major in the soil is not a major concernconcern

If any kind of space If any kind of space station were station were constructed on the constructed on the moon, radon would be moon, radon would be a major concern if lunar a major concern if lunar soil was used in soil was used in cementcement

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Apollo Mission DosesApollo Mission Doses

No significant No significant difference difference between between

Nuclear Radiation from a Planetary Nuclear Radiation from a Planetary SurfaceSurface

Effects on HealthEffects on Health

Worst-case scenario estimates an Worst-case scenario estimates an increase in carcinogenic risk of 45% to increase in carcinogenic risk of 45% to interplanetary astronauts.interplanetary astronauts.NASA/NCRP goal is 3%NASA/NCRP goal is 3%

Is difficult to quantify due to the uncertainty Is difficult to quantify due to the uncertainty in the knowledge of the biological in the knowledge of the biological response of to particles of various atomic response of to particles of various atomic numbers and energies.numbers and energies.

ConclusionsConclusions

Elevated or even fatal does to astronauts Elevated or even fatal does to astronauts are possible outside of Low Earth Orbit if are possible outside of Low Earth Orbit if proper planning is not doneproper planning is not done

Radionuclides in the soil may be a Radionuclides in the soil may be a concern for lunar basesconcern for lunar bases

Due to longer travel times, potential Due to longer travel times, potential missions to Mars would have to be ready missions to Mars would have to be ready for solar flaresfor solar flares

ReferencesReferences