Galactic cosmic radiation doses to astronauts outside the magnetosphere

Technical Report · Sun Dec 06 00:00:00 EST 1987

OSTI ID:6318929

Letaw, J R

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

Related Subjects

73 NUCLEAR PHYSICS AND RADIATION PHYSICS
63 RADIATION, THERMAL, AND OTHER ENVIRON. POLLUTANT EFFECTS ON LIVING ORGS. AND BIOL. MAT.
ASTRONAUTS
RADIATION DOSES
COSMIC RADIATION
DOSE EQUIVALENTS
CALCULATION METHODS
ATMOSPHERES
CARBON DIOXIDE
FUNCTIONS
GALAXIES
HUMAN FACTORS ENGINEERING
MOON
NEUTRONS
NUCLEI
PARTICLES
PROTONS
SHIELDING
SOLAR CYCLE
SPALLATION
SURFACES
THICKNESS
BARYONS
CARBON COMPOUNDS
CARBON OXIDES
CHALCOGENIDES
DIMENSIONS
DOSES
ELEMENTARY PARTICLES
ENGINEERING
FERMIONS
HADRONS
IONIZING RADIATIONS
NUCLEAR REACTIONS
NUCLEONS
OXIDES
OXYGEN COMPOUNDS
PERSONNEL
RADIATIONS
SATELLITES
654001* - Radiation & Shielding Physics- Radiation Physics
Shielding Calculations & Experiments
560151 - Radiation Effects on Animals- Man