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Radiation challenges for human exploration

Radiation challenges for human exploration. Marco Durante. Fourth European Space Weather Week, Bruxelles, Belgium, November the 9th, 2007. Is cosmic radiation a showstopper for the colonization of the Solar system?. The goal of space radiation biophysics research:.

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Radiation challenges for human exploration

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  1. Radiation challenges for human exploration Marco Durante Fourth European Space Weather Week, Bruxelles, Belgium, November the 9th, 2007

  2. Is cosmic radiation a showstopper for the colonization of the Solar system? The goal of space radiation biophysics research: To allow exploration and colonization with ACCEPTABLE risk from radiation exposure Astronauts go in EVA because they understand the risk!

  3. Health risks in space exploration • Harmful Radiation Effects • Cancer • Tissue degenerative effects (CNS, cardiovascular diseases, cataracts,…..) • Acute radiation sickness • Hereditary effects SPACE RADIATION • Behavioral Problems • Disorientation • Sleep problems • Psychosocial problems • Acute Medical Problems • • Toxicity • • Ambulatory health problems HUMAN FACTORS Concordia Mars-500 MICROGRAVITY • Physiological Changes • Cardiac arrhythmia • Osteoporosis • Fluid redistribution (puffy face, shrinked legs….) • Loss of blood plasma, anemia • Muscle loss • Kidney stones

  4. mSv 100000 10000 1000 100 10 1 0.1 Two major radiation risks in exploratory missions CNS syndrome Skin desquamation GI syndrome • SPE: sporadic, high dose. Shielding generally effective. Acute (deterministic) effects • GCR: chronic, low dose. Shielding poorly effective. Late (stochastic) effects Fibrosis Haematopoietic syndrome Vomiting Nausea Lymphopenia Azoospermia Annual dose in Kerala (India) Annual dose limit for radiation workers CT abdomen/pelvis Annual dose on Earth Daily dose in LEO Pelvis X-ray film Annual cosmic rays at sea level Chest X-ray film

  5. Radiation doses in different missions

  6. Radiation field on Mars About 100x Earth’s background

  7. Relative contribution of different components of space radiation to dose equivalent

  8. Solar particle events

  9. Modelling SPE • Worst case scenarios (NASA: 4xOct89, ESA TT: MaxSEP) are generally considerd to be potentially lethal • These events are very seldom For assessement of health risk, it is necessary to take into account • Significant sparing effect (usually dD/dt<10 cSv/h) • Contamination by HZE (high RBE) particles • Secondary radiation produced by shielding in high knee-energy events • Stochastic risk can be higher than nonstochastic ESA TT on shielding, final report, ESTEC SP-1281, June 2005

  10. Deterministic effects • Traditionally identified as nonstochastic early effects with threshold • Actually, they can be both early and late, and are probabilistic • Risk is dose-rate dependent ESA TT on shielding, final report, ESTEC SP-1281, June 2005

  11. Shielding of SPE – dose equivalent for WCS 4xOct1989 event

  12. SPE and late stochastic risk

  13. Galactic cosmic radiation

  14. GCR shielding (HZETRN calculation) Aluminum ~ 30% Polyethylene ~ 50% Liquid hydrogen ~ 90% Max GCR dose reduction

  15. Shielding on ISS Sleep station outfitted with PE and water Thin, flat panels are PE shields Stowage water packaging above the sleep station

  16. Space radiation biology

  17. Role of Uncertainties in Risk Projections 10% Maximum Acceptable Risk Mars Mission ▲ 1% ▲ ISS Mission SPE?? Lunar 0.1% ▲ “95% Confidence Interval” Shuttle Mission ▲ .01% “Point Estimate” Individual’s Fatal Risk

  18. DNA dsb visualized by immunofluorescence of g-H2AX histone in human skin firbroblasts exposed to 2 Gy of ionizing radiation g-rays silicon iron Cucinotta and Durante, Lancet Oncol. 2006

  19. “Special” chromosomal damage induced by low doses of heavy ions 3 Gy g -rays 0.3 Gy Fe-ions Durante et al., Radiation Research 2002

  20. Harderian gland tumors in mice Data Alpen et al. (1993); IPP Model Cucinotta, et al. (1994)

  21. AML incidence in CBA mice exposed to Fe-ions or g-rays Courtesy of M. Weil Radiation Leukemogenesis NSCOR

  22. Conclusions – SPE • Shielding will be very effective for any events with E<100-200 MeV • For soft events, main risks are accelerated cataractogenesis and skin erythema in EVA • For hard spectra, prodromal syndrome is possible (around 2xFeb 1956 intensities) • SPE will increase stochastic risk, especially leukemia • More research is needed in: RBE of H- and He-ions at low dose-rates, biomedical countermeasures for acute radiation sickness

  23. Conclusions – GCR • Current uncertainties on biological effects are too high for long-term exploratory missions, especially Mars • Passive shielding can only partly solve the problem, active shielding is not yet available • More research is needed on biological effects of heavy ions: cancer risk, CNS damage, interaction with other space environment stressors.

  24. Thank you very much!

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