radiation challenges for human exploration marco durante fourth european space weather week,...
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Radiation challenges for human exploration
Marco DuranteMarco Durante
Fourth European Space Weather Week, Bruxelles, Belgium, November the 9th, 2007
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?
Harmful Radiation Effects• Cancer• Tissue degenerative effects
(CNS, cardiovascular diseases, cataracts,…..)
• Acute radiation sickness• Hereditary effects
Health risks in space exploration
SPACERADIATION
HUMAN FACTORS
MICROGRAVITY
Behavioral Problems • Disorientation• Sleep problems • Psychosocial problemsAcute 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
Concordia Mars-500
Two major radiation Two major radiation risks in exploratory risks in exploratory
missionsmissions
SPESPE: sporadic, : sporadic, high dose. high dose. Shielding generally Shielding generally effective. Acute effective. Acute (deterministic) (deterministic) effectseffects
GCRGCR: chronic, low : chronic, low dose. Shielding dose. Shielding poorly effective. poorly effective. Late (stochastic) Late (stochastic) effectseffects
Annual dose on Earth
Daily dose in LEO
CT abdomen/pelvis
Annual dose limit for radiation workers
AzoospermiaLymphopeniaNauseaVomiting
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
Radiation doses in different missions
0.1
1
10
100
1000
104
1950 1960 1970 1980 1990 2000 2010 2020 2030
Dos
e (m
Sv)
Year
Gemini
Apollo
Skylab STS/Mir
Shuttle
ISS
Mars
Populationper year
RadWorkper year
Astronautscareer
Past Future
Radiation field on MarsRadiation field on Mars
About 100x Earth’s background
Relative contribution of different Relative contribution of different components of space radiation to components of space radiation to
dose equivalentdose equivalent
Solar particle events
Modelling SPEModelling SPE Worst case scenarios (NASA: Worst case scenarios (NASA:
4xOct89, ESA TT: MaxSEP) 4xOct89, ESA TT: MaxSEP) are generally considerd to be are generally considerd to be potentially lethalpotentially lethal
These events are very seldomThese events are very seldom
For assessement of health risk, it is necessary to take into account
Significant sparing effect Significant sparing effect (usually (usually dD/dtdD/dt<10 cSv/h)<10 cSv/h)
Contamination by HZE (high Contamination by HZE (high RBE) particlesRBE) particles
Secondary radiation produced Secondary radiation produced by shielding in high knee-by shielding in high knee-energy eventsenergy events
Stochastic risk can be higher Stochastic risk can be higher than nonstochasticthan nonstochastic
ESA TT on shielding, final report, ESTEC SP-1281, June 2005
Deterministic effectsDeterministic effects
Traditionally Traditionally identified as identified as nonstochastic nonstochastic early effects with early effects with thresholdthreshold
Actually, they Actually, they can be both early can be both early and late, and are and late, and are probabilisticprobabilistic
Risk is dose-rate Risk is dose-rate dependentdependent
0
0,2
0,4
0,6
0,8
1
0 5 10 15 20
Ris
k
Dose (Gy)
GI syndrome
Fibrosis
Vomiting
ESA TT on shielding, final report, ESTEC SP-1281, June 2005
Shielding of SPE – dose equivalent Shielding of SPE – dose equivalent for WCS 4xOct1989 eventfor WCS 4xOct1989 event
SPE and late stochastic riskSPE and late stochastic risk
Galactic cosmic radiation
GCR shielding (HZETRN calculation)
Aluminum ~ 30%
Polyethylene ~ 50%
Liquid hydrogen ~ 90%
Max GCR dose
reduction
Shielding on ISS
Sleep station outfitted with PE and waterThin, flat panels are PE shieldsStowage water packaging above the sleep station
Space radiation biology
Role of Uncertainties in Risk ProjectionsRole 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??
DNA dsb visualized by immunofluorescence of -H2AX histone in human skin firbroblasts exposed to 2 Gy of ionizing radiation
-rays
silicon
ironCucinotta and Durante, Lancet Oncol. 2006
“Special” chromosomal damage induced by low doses of heavy ions
3 Gy -rays 0.3 Gy Fe-ions
Durante et al., Radiation Research 2002
Harderian gland tumors in mice
Data Alpen et al. (1993); IPP Model Cucinotta, et al. (1994)
Fluence, m2
10-3 10-2 10-1 100 101 102 103
Tum
or P
reva
lenc
e (%
)
0
20
40
60
80
100
Iron
Neon
-rays
Proton
Helium
AML incidence in CBA mice exposed to
Fe-ions or -raysControl # mice total (still alive) AML % total
0 cGy 157 (23) 0 0
Gamma cGy # mice total (still alive) AML % total
100 400 (65) 4 1.0
200 300 (50) 16 5.3
300 100 (1) 9 9.0
HZE cGy # mice total (still alive) AML % total
10 300 (0) 0 0
20 300 (0) 0 0
40 200 (0) 1 0.5
100 200 (0) 3 1.5
Radiation Leukemogenesis NSCOR Courtesy of M. Weil
Conclusions – SPEConclusions – SPE
Shielding will be very effective for any events Shielding will be very effective for any events with E<100-200 MeVwith E<100-200 MeV
For soft events, main risks are accelerated For soft events, main risks are accelerated cataractogenesis and skin erythema in EVAcataractogenesis and skin erythema in EVA
For hard spectra, prodromal syndrome is For hard spectra, prodromal syndrome is possible (around 2xFeb 1956 intensities)possible (around 2xFeb 1956 intensities)
SPE will increase stochastic risk, especially SPE will increase stochastic risk, especially leukemialeukemia
More research is needed in: RBE of H- and He-More research is needed in: RBE of H- and He-ions at low dose-rates, biomedical ions at low dose-rates, biomedical countermeasures for acute radiation sicknesscountermeasures for acute radiation sickness
Conclusions – GCRConclusions – GCR
Current uncertainties on biological effects Current uncertainties on biological effects are too high for long-term exploratory are too high for long-term exploratory missions, especially Marsmissions, especially Mars
Passive shielding can only partly solve the Passive shielding can only partly solve the problem, active shielding is not yet problem, active shielding is not yet availableavailable
More research is needed on biological More research is needed on biological effects of heavy ions: cancer risk, CNS effects of heavy ions: cancer risk, CNS damage, interaction with other space damage, interaction with other space environment stressors.environment stressors.