Galactic cosmic radiation doses to astronauts outside the magnetosphere
The dose and dose equivalent from galactic cosmic radiation outside the magnetosphere were computed. The principal radiation components considered include primary cosmic rays, spallation fragments of the heavy ions, and secondary products (protons, neutrons, alphas, and recoil nuclei) from interactions in tissue. Three mission environments were considered: free space, the lunar surface, and the martian surface. The annual dose equivalents to the blood-forming organs in these environments are approximately 500 mSv, 250 mSv, and 120 mSv, respectively (1 mSv = 0.1 rem). The dose on the lunar surface is one-half of free space because there is only a single hemisphere of exposure. The dose on the martian surface is half again the dose on the moon because of the shielding provided by a thin, carbon dioxide atmosphere. Dose versus aluminum shielding thickness functions have been computed for the free space exposure. Galactic cosmic radiation is energetic and highly penetrating. 30 cm of aluminum shielding reduces the dose equivalent 25% to 40% (depending on the phase of the solar cycle). Aiming for conformity with the draft NCRP annual dose limit for space station crew members, which is 500 mSv/yr, we recommend 7.5 cm of aluminum shielding in all habitable areas of spacecraft designed for long-duration missions outside Earth's magnetosphere. This shielding thickness reduces the galactic cosmic ray dose and diminishes the risk to astronauts from energetic particle events.
- Research Organization:
- Severn Communications Corp., Severna Park, MD (USA)
- OSTI ID:
- 6318929
- Report Number(s):
- AD-A-203433/8/XAB; SCC-87-06
- Country of Publication:
- United States
- Language:
- English
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63 RADIATION, THERMAL, AND OTHER ENVIRON. POLLUTANT EFFECTS ON LIVING ORGS. AND BIOL. MAT.
654001* -- Radiation & Shielding Physics-- Radiation Physics
Shielding Calculations & Experiments
73 NUCLEAR PHYSICS AND RADIATION PHYSICS
ASTRONAUTS
ATMOSPHERES
BARYONS
CALCULATION METHODS
CARBON COMPOUNDS
CARBON DIOXIDE
CARBON OXIDES
CHALCOGENIDES
COSMIC RADIATION
DIMENSIONS
DOSE EQUIVALENTS
DOSES
ELEMENTARY PARTICLES
ENGINEERING
FERMIONS
FUNCTIONS
GALAXIES
HADRONS
HUMAN FACTORS ENGINEERING
IONIZING RADIATIONS
MOON
NEUTRONS
NUCLEAR REACTIONS
NUCLEI
NUCLEONS
OXIDES
OXYGEN COMPOUNDS
PARTICLES
PERSONNEL
PROTONS
RADIATION DOSES
RADIATIONS
SATELLITES
SHIELDING
SOLAR CYCLE
SPALLATION
SURFACES
THICKNESS