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Radiation Shielding of Lunar Spacecraft

  • T. G. Barnes
  • E. M. Finkelman
  • A. L. Barazotti

Abstract

A description of the radiation environment to be encountered in space is presented. Based on available experimental data, a model of the spatial, spectral, and temporal variation of charged particles from the Van Allen belts and cosmic radiation is established.

The attenuation of charged particles has been calculated using data on the range and relative energy loss as function of energy for protons and electrons in various materials. Calculations have been performed to determine the relative effectiveness of varying thicknesses of different shielding materials as a function of geometry of the shield. Shield weight penalties as a function of material and threshold energy for a representative hazard chamber are presented. Tissue dose rate variation with time for a typical three-dimensional lunar trajectory is presented and compared to flight radially in the plane of the magnetic equator. Total integrated biological dose as a function of carbon shield thickness was calculated for four solar-flare events, and for flight radially out through the inner belt. Considering the amounts of ablation material, structure, and equipment surrounding the crew in a reentry vehicle, it was found that the additional shielding required for traversal of the belts is small. It is shown that approximately 10 g/cm2 of carbon shielding is sufficient to shield not only the inner-belt protons, but would also provide adequate protection against solar flares of the magnitude that occurred in March and August of 1958. However, it was also found to be impossible to shield against solar flares of the highest known energy within the reasonable weight limits of a typical lunar mission. Since adequate shielding cannot be provided against these very intense solar proton events, the probability of encountering these and and various lesser intensity flares is extremely important. Accordingly, the probability of encountering solar protons as a function of mission time is presented. These encounter probabilities are considerably reduced if flares can be predicted. Continuing effort in this area indicates that some degree of solar-flare prediction is feasible.

Keywords

Solar Flare Radiation Belt Solar Proton Radiation Shielding Solar Proton Event 
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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References

  1. 1.
    Robert Jastrow(ed.) “Symposium on the Exploration of Space,” Journal of Geophysical Research, 64:11 (November 1959).Google Scholar
  2. 2.
    J. R. Winckler, “Balloon Study of High Altitude Radiations during the International Geophysical Year,” Journal of Geophysical Research, 65:5 (May 1960).Google Scholar
  3. 3.
    B. Peters, “Progress in Cosmic Ray Research since 1947,” Journal of Geophysical Research, 64:2 (February 1959).Google Scholar
  4. 4.
    Bruno Rossi, “Scientific Results of Experiments in Space,” Transactions, American Geophysical union, 41:3 (September 1960).CrossRefGoogle Scholar
  5. 5.
    J.R. Winckler, “Primary Cosmic Rays,” a paper presented at the Radiation Research Society Symposium, May 10, 1960.Google Scholar
  6. 6.
    J.A. Van Allen, and L.A. Frank, “Radiation Measurements to 658, 300 km with Pioneer IV,” State Univ. of Iowa Report SUI-59–18 (August 1959).Google Scholar
  7. 7.
    R.L. Arnoldy, R.A. Hoffman, and J.R. Winckler, “Observations of the Van Allen Radiation Regions during August and September 1959, Part I,” Journal of Geophysical Research, 64:11 (November 1959).Google Scholar
  8. 8.
    P. Rothwell and C.E. Mcllwain, “Magnetic Storms and the Van Allen Radiation Belts—Observations from Explorer IV,” Journal of Geophysical Research, 65:3 (March 1960).Google Scholar
  9. 9.
    S.C. Freden, and R.S. White, “Particle Fluxes in the Inner Radiation Belt,” Journal of Geophysical Research, 65:5 (May 1960).Google Scholar
  10. 10.
    K.A. Anderson, “Solar Particles and Cosmic Rays,” Scientific American, 202:6 (June 1960).CrossRefGoogle Scholar
  11. 11.
    G.C. Ried, and H. Leinbach, “Low Energy Cosmic-Ray Events Associated with Solar Flares,” Journal of Geophysical Research, 64:11 (November 1959).Google Scholar
  12. 12.
    E.P. Ney, J.R. Winckler, and P.S. Frier, “Protons from the Sun on May 12, 1959,” Physical Review Letters, 3:4 (1959).CrossRefGoogle Scholar
  13. 13.
    B.T. Price, C.C. Horton, and K.T. Spinney, Radiation Shielding, London, Pergammon Press, 1957.Google Scholar
  14. 14.
    W.L. Brown and G.L. Pearson, “Proton Radiation Damage in Silicon Solar Cells-Cases 38139–7 and 38788,” Company Memorandum, Murray Hill, N.J., Bell Telephone Labs, (June 30, 1960).Google Scholar
  15. 15.
    W.L. Brown and G.L. Pearson, “Electron Radiation Damage to Silicon Solar Cells-Cases 38139–7 and 38788,” Company Memorandum, Murray Hill, N.J., Bell Telephone Laboratories, (April 6, 1960; contains Lofersky and Rappaport data).Google Scholar
  16. 16.
    R.G. Downing, “Electron Bombardment of Silicon Solar Cells,“ ARS Report No. 1294–60 (September 1960).Google Scholar
  17. 17.
    A set of preliminary data curves received from the International Rectifier Corporation, E1 Segundo, California, September, 1960.Google Scholar
  18. 18.
    H.J. Schaeffer, “Radiation Danger in Space,” Astronautics (July 1960).Google Scholar
  19. 19.
    H.J. Schaeffer, a paper presented to the 2nd International Symposium on Physics and Medicine of the Atmosphere and Space (November 1958).Google Scholar
  20. 20.
    K.A. Anderson, “Prediction Aspects of Solar Proton Events,” July 1960.Google Scholar
  21. 21.
    K.A. Anderson, “Prediction Aspects of Solar Cosmic Ray Events—Preliminary Version,” October 4, 1960.Google Scholar

Copyright information

© Springer Science+Business Media New York 1962

Authors and Affiliations

  • T. G. Barnes
    • 1
  • E. M. Finkelman
    • 1
  • A. L. Barazotti
    • 1
  1. 1.Space Sciences GroupGrumman Aircraft Engineering CorporationBethpageUSA

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