What Will Still Remain Unknown, and What Risk Does This Represent?

The benefits gained from pursuing these strategies will be not only a reduction by a factor of 2 or more in the uncertainty in estimates of the risk of late effects for crew members exposed to radiation in space, but also greater understanding of CNS and other effects about which little is currently known. These benefits will result in a narrowing of the scope of the types and designs of shielding that need to be considered for crew protection, and thus should result in a significant cost savings. The liability of following these strategies is that the time required to complete them may delay a decision on shielding design and consideration of any near-term (within 25 years) launch dates if suitable resources are not made available to complete the research expeditiously.

Since these research strategies are narrowly focused and based entirely on current understanding of space radiation issues, there is also no guarantee that this approach will necessarily address all of the significant radiation hazards for crews of deep-space missions. Utilizing a wider range of radiation and biological models could lead to recognition of previously unappreciated hazards for those crews and reveal useful new avenues of research.


1. National Council on Radiation Protection and Measurements (NCRP). 1989. Guidance on Radiation Received in Space Activities. Recommendations of the National Council on Radiation Protection and Measurements. NCRP Report No. 98. National Council on Radiation Protection and Measurements, Bethesda, Md. See also Board on Radiation Effects Research, National Research Council. 1990. Health Effects of Exposure to Low Levels of Ionizing Radiation: BIER V. National Academy Press, Washington, D.C.

2. Fry, R.J.M. 1981. Experimental radiation carcinogenesis: What have we learned? Radiat. Res. 87:224–239.

3. Lett, J. T., Keng, P.C., Bergtold, D.S., and Howard, J. 1987. Effects of heavy ions on rabbit tissues: Induction of DNA strand breaks in retinal photoreceptor cells by high doses of radiation. Radiat. Environ. Biophys. 26: 23–36.

4. Lett, J.T., Cox, A.B., Keng, P.C., Lee, A.C., Su, C.M., and Bergtold, D.S. 1980. Late degeneration in rabbit tissues after irradiation by heavy ions. Pp. 131–142 in: Life Sciences and Space Research, Volume XVIII (R. Holmquist, ed.). Pergamon Press, Oxford. See also Lett et al., 1987, Effects of heavy ions on rabbit tissues; and Williams, G.R., and Lett, J.T. 1995. Damage to the photoreceptor cells of the rabbit retina from 56Fe ions: Effect of age at exposure. Adv. Space Res. 18: 55–58.

5. Wu, B., Medvedovsky, C., and Worgul, B.V. 1994. Non-subjective cataract analysis and its application in space radiation risk assessment. Adv. Space Res. 14: 493–500.

6. Parshad, R., Sanford, K.K., and Jones, G.M. 1983. Chromatid damage after G2 phase X-irradiation of cells from cancer-prone individuals implicates deficiency in DNA repair. Proc. Natl. Acad. Sci. U.S.A. 80: 5612–5616.

7. Sanford, K.K., Parshad, R., Gantt, R., Tarone, R.E., Jones, G.M., and Price, F.M. 1989. Factors affecting and significance of G2 chromatin radiosensitivity in predisposition to cancer. Int. J. Radiat. Biol. 55: 963–981.

8. Parshad, R., Price, F.M., Pirollo, K.F., Chang, E.H., and Sanford, K.K. 1993. Cytogenetic response to G2-phase X-irradiation in relation to DNA repair and radiosensitivity in a cancer-prone family with Li-Fraumeni syndrome. Radiat. Res. 136: 236–240.

9. Bender, M.A., Viola, M.V., Riore, J., Thompson, M.H., and Leonard, R.C. 1988. Normal G2 chromosomal radiosensitivity and cell survival in the cancer family syndrome. Cancer Res. 48: 2579–2584.

10. Scott, D., Spreadborough, A.R., Jones, L.A., Robert, S.A., and Moor, C.J. 1996. Chromosomal radiosensitivity in G2-phase lymphocytes as an indicator of cancer predisposition. Radiat. Res. 145:3–16.

11. Scott, D., Spreadborough, A., Levine, E., and Roberts, S.A. 1994. Genetic predisposition in breast cancer. Lancet 344: 1444.

12. Kranert, T., Schneider, E., and Kiefer, J. 1990. Mutation induction in V79 Chinese hamster cells by very heavy ions. Int. J. Radiat. Biol. 58: 975–987.

13. Belli, M., et al. 1993. Inactivation and mutation induction in V79 cells by low energy protons: Re-evaluation of the results at the LNL facility. Int. J. Radiat. Biol. 63: 331–337.

14. Stoll, U., Schmidt, A., Schneider, E., and Kiefer, J. 1995. Killing and mutation of Chinese hamster V79 cells exposed to accelerated oxygen and neon ions. Radiat. Res. 142: 288–294.

The National Academies | 500 Fifth St. N.W. | Washington, D.C. 20001
Copyright © National Academy of Sciences. All rights reserved.
Terms of Use and Privacy Statement