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Galactic Cosmic Radiation Doses to Astronauts Outside the Magnetosphere

  • John R. Letaw
  • Rein Silberberg
  • C. H. Tsao
Chapter
Part of the Nato ASI Series book series (NSSA, volume 154)

Abstract

The dose and dose equivalent from galactic cosmic radiation outside the magnetosphere have been computed. Each of the principal radiation components were considered. These include primary cosmic rays, spallation fragments of the heavy ions, and secondary products (protons, neutrons, alphas, and recoil nuclei) from interactions in tissue. COnventional quality factors were used in converting from dose to dose equivalent.

Three mission environments have been 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−1, 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.

Keywords

Dose Equivalent Lunar Surface Solar Energetic Particle Libration Point Cosmic Radiation 
These keywords were added by machine and not by the authors. This process is experimental and the keywords may be updated as the learning algorithm improves.

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Copyright information

© Plenum Press, New York 1988

Authors and Affiliations

  • John R. Letaw
    • 1
  • Rein Silberberg
    • 2
  • C. H. Tsao
    • 2
  1. 1.Severn Communications CorporationSeverna ParkUSA
  2. 2.E.O. Hulburt Center for Space Research, Naval Research LaboratoryUSA

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