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

2. 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! Is cosmic radiation a showstopper for the colonization of the Solar system?

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

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

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 Modelling SPE Worst case scenarios (NASA: 4xOct89, ESA TT: MaxSEP) are generally considerd to be potentially lethal Worst case scenarios (NASA: 4xOct89, ESA TT: MaxSEP) are generally considerd to be potentially lethal These events are very seldom 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) Significant sparing effect (usually dD/dt<10 cSv/h) Contamination by HZE (high RBE) particles Contamination by HZE (high RBE) particles Secondary radiation produced by shielding in high knee- energy events Secondary radiation produced by shielding in high knee- energy events Stochastic risk can be higher than nonstochastic 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 Traditionally identified as nonstochastic early effects with threshold Actually, they can be both early and late, and are probabilistic Actually, they can be both early and late, and are probabilistic Risk is dose-rate dependent Risk is dose-rate dependent ESA TT on shielding, final report, ESTEC SP-1281, June 2005

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

13. SPE and late stochastic risk

14. Galactic cosmic radiation

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

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

17. Space radiation biology

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

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

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

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

22. AML incidence in CBA mice exposed to Fe-ions or  -rays Control# mice total (still alive)AML% total 0 cGy157 (23)00 Gamma cGy# mice total (still alive)AML% total 100400 (65)41.0 200300 (50)165.3 300100 (1)99.0 HZE cGy# mice total (still alive)AML% total 10300 (0)00 20300 (0)00 40200 (0)10.5 100200 (0)31.5 Radiation Leukemogenesis NSCOR Courtesy of M. Weil

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

24. Conclusions – GCR Current uncertainties on biological effects are too high for long-term exploratory missions, especially Mars 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 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. More research is needed on biological effects of heavy ions: cancer risk, CNS damage, interaction with other space environment stressors.