Surviving in space: the challenges of a manned mission to Mars
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Transcript of Surviving in space: the challenges of a manned mission to Mars
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Surviving in space: the challenges Surviving in space: the challenges of a manned mission to of a manned mission to MarsMars
Lecture 3Lecture 3Modeling the Interaction of the Modeling the Interaction of the
Space Radiation in Spacecraft & Space Radiation in Spacecraft & Humans, and Assessing the Risks Humans, and Assessing the Risks
on a Mission to Marson a Mission to Mars
CERN Course – Lecture 3October 28, 2005 – L. Pinsky
Modeling the Interaction of the Space Radiation in Spacecraft & Humans, and
Assessing the Risks on a Mission to Mars
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Back to the Moon…Then, On to Mars
• President Bush has committed the US Space Program to going to Mars…
• The first step will be a return to the Moon to develop and test the techniques needed eventually to go to Mars…
• Crew radiation exposure has been identified as one of the major problems that must be dealt with to make this possible…
CERN Course – Lecture 3October 28, 2005 – L. Pinsky
Modeling the Interaction of the Space Radiation in Spacecraft & Humans, and
Assessing the Risks on a Mission to Mars
3
Radiation Exposure Guidelines
• Recall that astronauts will be held to the same exposure limits in terms of risk to health that ground-based atomic workers are!
• Nominally, for chronic exposure threats the biggest risk is radiation-induced cancer, and the current exposure guideline is to keep the Excess Lifetime Risk (ELR) to under 3%...
CERN Course – Lecture 3October 28, 2005 – L. Pinsky
Modeling the Interaction of the Space Radiation in Spacecraft & Humans, and
Assessing the Risks on a Mission to Mars
4
Mars Reference Mission
CERN Course – Lecture 3October 28, 2005 – L. Pinsky
Modeling the Interaction of the Space Radiation in Spacecraft & Humans, and
Assessing the Risks on a Mission to Mars
5
Reference Mars Vehicles
CERN Course – Lecture 3October 28, 2005 – L. Pinsky
Modeling the Interaction of the Space Radiation in Spacecraft & Humans, and
Assessing the Risks on a Mission to Mars
6
CERN Course – Lecture 3October 28, 2005 – L. Pinsky
Modeling the Interaction of the Space Radiation in Spacecraft & Humans, and
Assessing the Risks on a Mission to Mars
7
Exposure Regimes• Trans-Mars & Trans-Earth Vehicle
– Normal Crew Compartment– “Storm Shelter” within Vehicle– Spacesuit EVAs
• Martian Surface– Within Surface Habitat– Possible “Storm Shelter” within Habitat– EVA Vehicle– Spacesuit EVAs
CERN Course – Lecture 3October 28, 2005 – L. Pinsky
Modeling the Interaction of the Space Radiation in Spacecraft & Humans, and
Assessing the Risks on a Mission to Mars
8
DEEP SPACE GCR DOSESTrans-Mars & Trans-Earth
• Annual bone marrow GCR doses will range up to ~ 15 cGy at solar minimum (~ 40 cSv) behind ~ 2cm Al shielding
• Effective dose at solar minimum is ~ 45-50 cSv per annum
• At solar maximum these are ~ 15-18 cSv• Secondary neutrons and charged particles are the
major sources of radiation exposure in an interplanetary spacecraft
• No dose limits yet for these missions
Courtesy of L. Townsend, US NCRP
CERN Course – Lecture 3October 28, 2005 – L. Pinsky
Modeling the Interaction of the Space Radiation in Spacecraft & Humans, and
Assessing the Risks on a Mission to Mars
9
Annual GCR Doses
Al Shield
(g cm-2)
Skin Bone Marrow
Annual Effective
Dose (cSv)
Annual Dose
(cGy)
Annual Dose
Equiv.
(cSv)
Annual Dose
(cGy)
Annual Dose
Equiv.
(cSv)
1970-71 Solar Maximum
1 6.2 27.4 5.7 16.7 17.9
5 6.4 24.6 5.8 15.6 16.7
10 6.5 21.8 5.8 14.6 15.4
Courtesy of L. Townsend, US NCRP
CERN Course – Lecture 3October 28, 2005 – L. Pinsky
Modeling the Interaction of the Space Radiation in Spacecraft & Humans, and
Assessing the Risks on a Mission to Mars
10
Solar Min Annual GCR Dose
Al Shield
(g cm-2)
Skin Bone Marrow
Annual Effective
Dose (cSv)
Annual Dose
(cGy)
Annual Dose
Equiv.
(cSv)
Annual Dose
(cGy)
Annual Dose
Equiv.
(cSv)
1977 Solar Minimum
1 18.4 79.8 16.4 44.5 48.8
5 18.3 66.9 16.3 40.5 43.7
10 18.0 56.2 16.1 37.0 39.3
Courtesy of L. Townsend, US NCRP
CERN Course – Lecture 3October 28, 2005 – L. Pinsky
Modeling the Interaction of the Space Radiation in Spacecraft & Humans, and
Assessing the Risks on a Mission to Mars
11
GCR Risks• Clearly, annual doses < 20cGy present no acute health
hazard to crews on deep space missions• Hence only stochastic effects such as cancer induction
and mortality or late deterministic effects, such as cataracts or damage to the central nervous system are of concern.
• Unfortunately, there are NO DATA NO DATA for human exposures from these radiations that can be used to estimate risks to crews
• In fact, as noted yesterday, it is not clear that the usual methods of estimating risk by calculating dose equivalent are even appropriate for these particles
Courtesy of L. Townsend, US NCRP
CERN Course – Lecture 3October 28, 2005 – L. Pinsky
Modeling the Interaction of the Space Radiation in Spacecraft & Humans, and
Assessing the Risks on a Mission to Mars
12
From NASA 1996Strategic Program Plan
CERN Course – Lecture 3October 28, 2005 – L. Pinsky
Modeling the Interaction of the Space Radiation in Spacecraft & Humans, and
Assessing the Risks on a Mission to Mars
13
10 YEAR CAREER EFFECTIVE DOSE LIMITS (Sv)
(NCRP Report 132)
Age at Exposure (y) Female Male
25 0.4 0.7
35 0.6 1.0
45 0.9 1.5
55 1.7 3.0
Courtesy of L. Townsend, US NCRP
CERN Course – Lecture 3October 28, 2005 – L. Pinsky
Modeling the Interaction of the Space Radiation in Spacecraft & Humans, and
Assessing the Risks on a Mission to Mars
14
Dose v. Shielding DepthFor Various Materials
From NASA CP3360, J.W.Wilson et al., eds.
CERN Course – Lecture 3October 28, 2005 – L. Pinsky
Modeling the Interaction of the Space Radiation in Spacecraft & Humans, and
Assessing the Risks on a Mission to Mars
15
Cosmic Rays and Nuclear Physics
• NASANASA Sponsors Nuclear Modeling to Obtain Nucleus-Nucleus EVENT GENERATORS for use in Monte Carlo Transport Codes…
• Like FLUKAFLUKA…– We have embedded DPMJETDPMJET 2.5 & 3
(for E > 5 GeV/A)– as well as RQMDRQMD
(for 100 MeV/A < E < 5 GeV/A)
CERN Course – Lecture 3October 28, 2005 – L. Pinsky
Modeling the Interaction of the Space Radiation in Spacecraft & Humans, and
Assessing the Risks on a Mission to Mars
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…And, There is an OngoingNASA-Sponsored Program to Improve the
Accuracy of the Event Generators• There is a Dual Program to Both Model and
Measure Cross Sections…– The Focus is on the E < 5GeV/A Region…– Several Approaches are being taken…– The NASA-FLUKA Team is developing a new
Hamiltonian QMD Formalism (HQMD).• These Improvements will Directly benefit many
Cosmic Ray Applicatons…– Air Shower Calculations…– Galactic Transport Calculations…– Experimental Corrections…
CERN Course – Lecture 3October 28, 2005 – L. Pinsky
Modeling the Interaction of the Space Radiation in Spacecraft & Humans, and
Assessing the Risks on a Mission to Mars
17
FLUKA rQMDFragmentation Yields
CERN Course – Lecture 3October 28, 2005 – L. Pinsky
Modeling the Interaction of the Space Radiation in Spacecraft & Humans, and
Assessing the Risks on a Mission to Mars
18
FLUKA Simulations
“GOLEM” Voxel Phantom in FLUKA
CERN Course – Lecture 3October 28, 2005 – L. Pinsky
Modeling the Interaction of the Space Radiation in Spacecraft & Humans, and
Assessing the Risks on a Mission to Mars
19
FLUKA MIR TPEC Simulations
Neutron Fluences
(Note the albedo fluences outside of the phantom…)
Charged Particle Fluences
CERN Course – Lecture 3October 28, 2005 – L. Pinsky
Modeling the Interaction of the Space Radiation in Spacecraft & Humans, and
Assessing the Risks on a Mission to Mars
20
NASA Revised Standard for Radiation Limits Revised standard applies a 95%
confidence level to the career limit of 3% risk of lifetime fatal cancer Approved by NASA Medical
Policy Board 95% confidence is conservative
Takes specific risk probabilities of individuals into account
Narrows range of increased risk
Epidemiology, DDREF (Dose and Dose Rate Effectiveness Factor), quality (QF) and dosimetry uncertainties part of evaluation
“Lack of knowledge” leads to costs and restrictions
ISS Mission Nominal Fatal Cancer Risk
% Fatal Risk per
0 1 2 3 4 5 6
Pro
babi
lity
0.0000
0.0025
0.0050
0.0075
0.0100
0.0125
0.0150
Risk DistributionD = 100 mGy E = 252 mSvQ = 2.52R0 = 1.0 %
95% C.I. = [0.41, 3.02%]
Slide Courtesy of F. Cucinotta, NASA/JSC
CERN Course – Lecture 3October 28, 2005 – L. Pinsky
Modeling the Interaction of the Space Radiation in Spacecraft & Humans, and
Assessing the Risks on a Mission to Mars
21
4-6 crew to Low Earth OrbitCrew Exploration Vehicle: Launch EnvironmentLEO EnvironmentEarth entry, water (or land) recovery
4-6 crew to lunar surface for extended-duration stayCEV:Earth-moon cruise – 4 daysLow lunar orbit (LLO) operations- 1 dayUntended lunar orbit operations – 4-14 daysLow lunar orbit operations – 1 dayMoon-Earth cruise – 4 days
Lunar Lander: Lunar surface operations 60-90 days
Crew TBD to Mars VicinityTransit vehicle: Earth-Mars cruise – 6-9 monthsMars vicinity operations – 30-90 daysMars-Earth cruise – 9-12 months
4-6 crew to lunar surface for long-duration stayLunar Habitat: Lunar surface operations 60-90 days
Crew TBD to Mars surfaceSurface Habitat
2030+
2020
2025+
2014
2015-2020
NASA ESMDSlide Courtesy of F. Cucinotta, NASA/JSC
CERN Course – Lecture 3October 28, 2005 – L. Pinsky
Modeling the Interaction of the Space Radiation in Spacecraft & Humans, and
Assessing the Risks on a Mission to Mars
22
1.E-05
1.E-04
1.E-03
1.E-02
1.E-01
1.E+00
1.E+01
1.E+02
0 40 80 120 160 200 240
Time, h
Do
se
Rat
e,
cS
v/h
Al thickness,
g/cm2:
0135
10152030
1 rem/h
August 1972 Solar Particle Event
Depth Alum Poly
5 61.1 39.1
10 20.9 10.7
20 4.57 1.83
BFO Dose, rem (cSv)
Slide Courtesy ofF. Cucinotta, NASA/JSC
CERN Course – Lecture 3October 28, 2005 – L. Pinsky
Modeling the Interaction of the Space Radiation in Spacecraft & Humans, and
Assessing the Risks on a Mission to Mars
23
GCR and SPE Dose: Materials & Tissue- GCR much higher energy producing secondary radiation
Shielding Depth, g/cm20 5 10 15 20 25 30 35
Do
se E
qu
iva
len
t, r
em
/yr
1
10
100
1000
10000
GCR L. HydrogenGCR PolyethyleneGCR GraphiteGCR AluminumGCR RegolithSPE GraphiteSPE Regolith
No Tissue Shielding With Tissue Shielding
August 1972 SPEShielding Depth, g/cm2
0 5 10 15 20 25 30 35
Dos
e E
quiv
alen
t, re
m/y
r1
10
100
1000
10000GCR L. HydrogenGCR PolyethyleneGCR GraphiteGCR AluminumGCR RegolithSPE GraphiteSPE RegolithSPE L. Hydrogen
Slide Courtesy of F. Cucinotta, NASA/JSC
CERN Course – Lecture 3October 28, 2005 – L. Pinsky
Modeling the Interaction of the Space Radiation in Spacecraft & Humans, and
Assessing the Risks on a Mission to Mars
24
Fatal Cancer Risk at Solar MinimumMinimum(20 g/cm2 Aluminum Shielding)
Mission D, Gy E, Sv %REID 95% CI
Males
Lunar (90 d) 0.03 0.071 0.28 [0.09,0.96]
Mars (600 d) 0.36 0.87 3.2 [1.0,10.5]
Mars (1000 d) 0.41 0.96 3.4 (3.2)* [1.1,11.0]
Females
Lunar (90 d) 0.03 0.071 0.34 [0.11,1.2]
Mars (600 d) 0.36 0.87 3.9 [1.2, 12.8]
Mars (1000 d) 0.41 0.96 4.1 (4.5)** [1.4, 14.4]
*Parenthesis exclude Prostate cancer; **Parenthesis LSS-report 12 (others report 13)Slide Courtesy of F. Cucinotta, NASA/JSC
CERN Course – Lecture 3October 28, 2005 – L. Pinsky
Modeling the Interaction of the Space Radiation in Spacecraft & Humans, and
Assessing the Risks on a Mission to Mars
25
Fatal Cancer Risk near Solar MaximumMaximum*(Males)
Mission D, Gy E, Sv %REID 95% CI
5 g/cm2 Al
Lunar (90 d) 0.45 0.69 2.7 [0.92,7.4]
Lunar (600 d) 0.63 1.21 4.4 [1.5,13.3]
Lunar (1000 d) 0.66 1.24 4.4 [1.5,13.0]
20 g/cm2 Al
Lunar (90 d) 0.042 0.09 0.35 [0.11,1.2]
Mars (600 d) 0.22 0.54 2.0 [0.65, 6.8]
Mars (1000 d) 0.25 0.60 2.1 [0.69, 7.2]
*Phi=1100 MV (solar modulation) with Aug. 1972 SPE in transit
Slide Courtesy of F. Cucinotta, NASA/JSC
CERN Course – Lecture 3October 28, 2005 – L. Pinsky
Modeling the Interaction of the Space Radiation in Spacecraft & Humans, and
Assessing the Risks on a Mission to Mars
26
Material Shielding and GCR Risks
• Do materials rich in hydrogen and other light atomic mass atoms significantly reduce GCR risks?
• Possible advantages– High Z/A ratio increases stopping effectiveness– Higher projectile fragmentation per unit mass in hydrogen– Reduced target fragmentation per unit mass in hydrogen
• Possible physics limitations to GCR shielding approaches– GCR not stopped in practical amounts of shielding– Target fragmentation is largely short-range and correlated with
projectile track– Target fragments in tissue occur for all materials and largely produced
by relativistic ions not absorbed by shielding• Do the biological uncertainties prevent us from knowing?
CERN Course – Lecture 3October 28, 2005 – L. Pinsky
Modeling the Interaction of the Space Radiation in Spacecraft & Humans, and
Assessing the Risks on a Mission to Mars
27
Significance of Shielding Materials for GCRSpiral 4 (40-yr Males): 20 g/cm2 Shields
(%) Fatal Cancer Risk
0 3 6 9 12 15
Pro
babi
lity
0.000
0.003
0.006
0.009
0.012
0.015
Distribution aluminumDistribution polyethyleneDistribution Liq. Hydrogen (H2) E(alum) = 0.87 Sv E(poly) = 0.77 SvE(H2) = 0.43 SvR(alum) = 3.2 [1.0,10.5] (%)R(poly) = 2.9 [0.94, 9.2] (%)R(H2) = 1.6 [0.52, 5.1] (%)
Slide Courtesy of F. Cucinotta, NASA/JSC
CERN Course – Lecture 3October 28, 2005 – L. Pinsky
Modeling the Interaction of the Space Radiation in Spacecraft & Humans, and
Assessing the Risks on a Mission to Mars
28
2 test at solar minimum for 20 g/cm2 shields for 40-yr males on Mars swing-by mission. P(n,2) is the probability materials can not be determined to be significantly different (n=500). Values in bold for P(n,2)<0.2 indicate a significant improvement over aluminum. Test Material E, Sv REID(%) 95% CL 2/n P(n,2) All Uncertainties Aluminum 0.87 3.2 [1.0, 10.5] - - Polyethylene 0.78 2.9 [0.94, 9.2] 0.05 >0.99 Hydrogen 0.43 1.6 [0.52, 5.1] 0.63 >0.99 LET-dependent Uncertainties Aluminum 0.87 3.2 [1.9, 8.7] - - Polyethylene 0.78 2.9 [1.8, 7.5] 0.08 >0.99 Hydrogen 0.43 1.7 [1.0, 4.2] 1.10 <0.15 Solar maximum for 5 g/cm2 shields. Test Material E, Sv REID(%) 95% CL 2/n P(n,2) All Uncertainties Aluminum 1.21 4.4 [1.5, 13.1] - - Polyethylene 0.94 3.5 [1.2, 10.8] 0.14 >0.99 Hydrogen 0.52 2.1 [0.60, 6.4] 0.81 >0.99 LET-dependent Uncertainties Aluminum 1.21 4.4 [3.0. 11.0] - - Polyethylene 0.94 3.5 [2.3, 8.8] 0.32 >0.99 Hydrogen 0.52 2.1 [1.2, 5.2] 1.38 <0.001
Significance Tests of Shielding Effectiveness
Slide Courtesy of F. Cucinotta, NASA/JSC
CERN Course – Lecture 3October 28, 2005 – L. Pinsky
Modeling the Interaction of the Space Radiation in Spacecraft & Humans, and
Assessing the Risks on a Mission to Mars
29
Future approaches• Lack of data for hazard rates for carcinogenesis in model systems drives
uncertainties
• Current model for fluence F, and LET, L
• Biological based models will consider incidence in model systems for various radiation qualities and dose-rates
– Knudson-Moolgavkar approach mutation rates 1 and 2; expansion rate
– Extension introduce covariates for radiation type, dose, and dose-rate into model parameters
• Track structure/Repair Kinetics IPP Models (Cucinotta and Wilson, 1995)– Extend IPP models to include track structure and repair kinetics effects on initiation or
promotion rates, cell killing of target cells, etc.
– Requires mechanistic assumption on initiation processes (mutation, LOH, CI, number and nature of steps, etc)
)],()1(),()([)(
),,( aaEARvaaMavERRFLDDREF
LQaaEh EcEE E
)))(exp(()(),(),(),( 2221, ataNLFLFaaEh TE
Slide Courtesy of F. Cucinotta, NASA/JSC
CERN Course – Lecture 3October 28, 2005 – L. Pinsky
Modeling the Interaction of the Space Radiation in Spacecraft & Humans, and
Assessing the Risks on a Mission to Mars
30
Radiation Quality in Track Structure Models-possible advantages of Bayesian Statistics
Slide Courtesy of F. Cucinotta, NASA/JSC
CERN Course – Lecture 3October 28, 2005 – L. Pinsky
Modeling the Interaction of the Space Radiation in Spacecraft & Humans, and
Assessing the Risks on a Mission to Mars
31
CONCLUSIONS - GCR• Cancer risks for exploration missions
– Risks from GCR are 2 to 5 percent mortality with upper 95% C.I. exceeding 10% for both males and females
• Shielding will not significantly reduce GCR risks
• Materials have unknown benefits because of biological uncertainties
– Risks from SPE are manageable with shielding approaches• Hydro-carbon shields offer a mass reduction over Aluminum shields of factor of
two or more for acute effects from most SPE spectra
• Benefits for cancer risk reduction are similar, however not significant for poly or similar materials again due to biological uncertainties
• Uncertainty factors of 4-fold for GCR and 2.5 fold for SPE do not include several model assumptions– Uncertainties for Mars mission likely higher than estimated here
• Exploration vehicle shielding should focus on SPE not GCR
Slide Courtesy of F. Cucinotta, NASA/JSC
CERN Course – Lecture 3October 28, 2005 – L. Pinsky
Modeling the Interaction of the Space Radiation in Spacecraft & Humans, and
Assessing the Risks on a Mission to Mars
32
New Methods
FLUKAGCR and SPE spectra
Quality factors Yields of “Complex Lesions”
Dose
Equivalent dose
“Biological dose”
(Complex Lesions/cell)
30 DNA base-pairs
mathematical phantom (68 regions)
“voxel” phantom (287 regions, 2x106 voxels)
Courtesy of F. Balarini
CERN Course – Lecture 3October 28, 2005 – L. Pinsky
Modeling the Interaction of the Space Radiation in Spacecraft & Humans, and
Assessing the Risks on a Mission to Mars
33
The FLUKA Monte Carlo code
hadron-hadron and hadron-nucleus interactions 0-100 TeV nucleus-nucleus interactions 5 GeV/u-10,000 TeV/u (DPMJET) electromagnetic and interactions 0-100 TeV neutron multigroup transport and interactions 0-20 MeV
nucleus-nucleus interactions below 5 GeV/u down to 100 MeV/u (by coupling with the RQMD 2.4 code)
parallel development of an original non-relativistic QMD code down to 20 MeV/u
Courtesy of F. Balarini
CERN Course – Lecture 3October 28, 2005 – L. Pinsky
Modeling the Interaction of the Space Radiation in Spacecraft & Humans, and
Assessing the Risks on a Mission to Mars
34
August 1972 SPE - comparison to NCRP limits
1 13.31 11.63 6.89 8.01 1.80 2.76
2 7.25 6.57 4.90 5.81 1.32 1.95
5 2.23 2.11 1.60 1.79 0.62 0.88
10 0.62 0.60 0.56 0.42 0.25 0.33 !!!
Skin Lens BFO
NCRP limits for 30 days LEO missions: 1.5, 1.0 and 0.25 Gy-Eq for skin, lens and BFO, respectively a 10 g/cm2 Al storm shelter would provide adequate protection
Erma Golem Erma Golem Erma Golem
Al shield
(g/cm2)
Courtesy of F. Balarini
CERN Course – Lecture 3October 28, 2005 – L. Pinsky
Modeling the Interaction of the Space Radiation in Spacecraft & Humans, and
Assessing the Risks on a Mission to Mars
35
GCR - comparison with skin dose results obtained with HZETRN+CAM (Wilson et al. 1997, NASA TP 3682)
This work Wilson et al.
Al Shield (g/cm2)
1 0.51 0.56 0.16 0.19
5 0.52 0.57 0.17 0.20
10 0.53 0.56 0.19 0.21
20 0.56 0.55 0.23 0.21
This work Wilson et al.
Solar min. (mGy/d) Solar max. (mGy/day)
Courtesy of F. Balarini
CERN Course – Lecture 3October 28, 2005 – L. Pinsky
Modeling the Interaction of the Space Radiation in Spacecraft & Humans, and
Assessing the Risks on a Mission to Mars
36
GCR proton component - skin doses
• increase of proton doses (all dose types) with Al shielding thickness
• large role of nuclear reaction products, especially for equivalent and “biological” dose
0
0.05
0.1
0.15
0.2
0.25
0.3
0.35
0.4
0.3 1 2 3 5 10
Al thickness (g*cm-2)
mG
y*d
-1
Total Primary Secondary Hadrons Electromagnetic
0.00E+00
5.00E-05
1.00E-04
1.50E-04
2.00E-04
2.50E-04
0.3 1 2 3 5 10
Al thickness (g*cm-2)
Cl*
cell
-1*d
-1
Total Primary Secondary Hadrons Electromagnetic
0
0.1
0.2
0.3
0.4
0.5
0.6
0.7
0.3 1 2 3 5 10
Al thickness (g*cm-2)
mS
v*d
-1
Total Primary Secondary Hadrons Electromagnetic
Skin Dose [mGy/d] Equivalent Dose [mSv/d]
“Biological” Dose [(CL/cell)/d]
Courtesy of F. Balarini
CERN Course – Lecture 3October 28, 2005 – L. Pinsky
Modeling the Interaction of the Space Radiation in Spacecraft & Humans, and
Assessing the Risks on a Mission to Mars
37
August 1972 SPE - skin doses
• dramatic dose decrease with increasing shielding (from 13.3 to 0.62 Sv in the range 1-10 g/cm2)
• major contribution from primary protons (the role of nuclear reaction products is not negligible only for equivalent and “biological” dose)
• similar trends for equivalent and “biological” dose
skin dose (Gy) skin equivalent dose (Sv)
skin “biological” dose (CLs/cell)
Courtesy of F. Balarini
CERN Course – Lecture 3October 28, 2005 – L. Pinsky
Modeling the Interaction of the Space Radiation in Spacecraft & Humans, and
Assessing the Risks on a Mission to Mars
38
August 1972 SPE - skin vs. internal organs
• much lower doses to liver than to skin (e.g. 1.0 vs. 13.3 Sv behind 1 g/cm2 Al )
• larger relative contribution of nuclear reaction products for liver than for skin (e.g. 14% vs. 7% behind 1 g/cm2 Al)
0
0.2
0.4
0.6
0.8
1
1.2
1 2 5 10 20
Al thickness (g/cm2)
Total Primary Protons Secondary Hadrons
Equivalent dose to skin (Sv) Equivalent dose to liver (Sv)
Courtesy of F. Balarini
CERN Course – Lecture 3October 28, 2005 – L. Pinsky
Modeling the Interaction of the Space Radiation in Spacecraft & Humans, and
Assessing the Risks on a Mission to Mars
39
Aug. 1972 and Oct. 1989 SPEs -Effective Dose (Sv)
Al shield August 1972 (Erma) October 1989 (Erma)
(g/cm2) E E* E*NASA E E* E*NASA
1 2.04 1.35 1.31 1.11 0.78 0.78
2 1.43 0.95 0.94 0.79 0.55 0.58
5 0.63 0.43 0.52 0.42 0.30 0.33
10 0.23 0.17 0.27 0.20 0.15 0.18
• large contribution (33-50%) from gonads, especially with small shielding
• E* values (by neglecting gonads) very similar to those calculated with the BRYNTRN code and the CAM phantom (Hoff et al. 2002, J. Rad. Res. 43)
Courtesy of F. Balarini
CERN Course – Lecture 3October 28, 2005 – L. Pinsky
Modeling the Interaction of the Space Radiation in Spacecraft & Humans, and
Assessing the Risks on a Mission to Mars
40
GCR at solar min. (=465 MV) - skin doses
• roughly constant skin dose (decrease in heavy-ion contribution balanced by increase in light-ion contribution) with increasing shielding; decrease of skin equivalent and “biological” doses starting from 2 g/cm2
• much larger relative contribution of heavy ions for the skin equivalent and “biological” dose than for the skin dose
0
0.1
0.2
0.3
0.4
0.5
0.6
0.3 1 2 3 5
Al thickness (g*cm-2)Total Proton Alpha 3≤Z≤10 11≤Z≤20 21≤Z≤28
00.20.40.60.8
11.21.41.61.8
2
0.3 1 2 3 5
Al thickness (g*cm-2)
Total Proton Alpha 3≤Z≤10 11≤Z≤20 21≤Z≤28
Skin Dose [mGy/d] Skin Equivalent Dose [mSv/d]
Skin “Biological” Dose [(CL/cell)/d]
Courtesy of F. Balarini
CERN Course – Lecture 3October 28, 2005 – L. Pinsky
Modeling the Interaction of the Space Radiation in Spacecraft & Humans, and
Assessing the Risks on a Mission to Mars
41
GCR at solar min. (=465 MV) - skin vs. internal organs
With respect to skin, internal organs have 1) similar dose (0.5 mGy/day) but smaller equivalent dose ( 1.3 vs. 1.7 mSv/day); 2) larger relative contributions from nuclear interaction products
skin liver
0
0.1
0.2
0.3
0.4
0.5
0.6
0.3 1 2 3 5
Al thickness (g*cm-2)
mG
y*d
-1
Total Primary Ions Secondary Hadrons Electromagnetic
0
0.1
0.2
0.3
0.4
0.5
0.6
0.3 1 2 3 5
Al thickness (g*cm-2)
mG
y*d
-1
Total Primary Ions Secondary Hadrons Electromagnetic
0
0.5
1
1.5
2
0.3 1 2 3 5
Al thickness (g*cm-2)m
Sv
*d-1
Total Primary Ions Secondary Hadrons Electromagnetic
0
0.5
1
1.5
2
0.3 1 2 3 5
Al thickness (g*cm-2)
mS
v*d-1
Total Primary Ions Secondary Hadrons Electromagnetic
Courtesy of F. Balarini
CERN Course – Lecture 3October 28, 2005 – L. Pinsky
Modeling the Interaction of the Space Radiation in Spacecraft & Humans, and
Assessing the Risks on a Mission to Mars
42
GCR at solar min. - Annual Effective Dose (Sv)
NCRP recommendations for LEO a 2-year mission to Mars at solar minimum would allow us to respect the career limits for males of at least 35 years-old (limit: <1 Sv) and females of at least 45 (limit: < 0.9 Sv) THAT is IF the Same Limits Apply!
0.3 0.47 0.43 0.37
1 0.47 0.44 0.38 0.49 0.37
2 0.46 0.41 0.35 0.47 0.36
3 0.43 0.41 0.35 0.44 0.33
5 0.42 0.42 0.34 0.39 0.30
Al (g/cm2) This work (male)
This work (female)
This work (no gonads)
Hoff et al. (male)
Hoff et al. (no gonads)
• large contribution from gonads, especially with small shielding (30% at 2 g/cm2)
• results very similar to those calculated with the HZETRN code and the CAM model (Hoff et al. 2002, J. Rad. Res. 43)
Courtesy of F. Balarini
CERN Course – Lecture 3October 28, 2005 – L. Pinsky
Modeling the Interaction of the Space Radiation in Spacecraft & Humans, and
Assessing the Risks on a Mission to Mars
43
Conclusions - SPEs
calculation of:
- dose decrease with increasing shielding
- differences between internal organs and skin
- relative contribution of primary protons and secondaries
- contribution to effective dose from gonads
Concludes that in case of an SPE similar to the August 1972 event, a 10 g/cm2 Al storm shelter should allow us to respect the 30-days NCRP limit.
Courtesy of F. Balarini
CERN Course – Lecture 3October 28, 2005 – L. Pinsky
Modeling the Interaction of the Space Radiation in Spacecraft & Humans, and
Assessing the Risks on a Mission to Mars
44
Future developments
Further validation of the FLUKA Monte Carlo code in space radiation protection problems with
simple shielding geometry
Repetition for more realistic geometries of shielding and spacecraft
Ultimately, we will need to assess the risk from this kind of radiation field, and that is a Biology Problem,
not a physics challenge…
CERN Course – Lecture 3October 28, 2005 – L. Pinsky
Modeling the Interaction of the Space Radiation in Spacecraft & Humans, and
Assessing the Risks on a Mission to Mars
45
Modeling Lunar & Martian Surface Radiation Environments
• We need to start with the Free Space Fluences• For the Moon, we can just calculate the albedo
produced by the impact of the primary fluences and add one half the free space fluence to the albedo.
• For Mars, we have to propagate the free space fluence through the atmosphere to and into the surface materials. Then examine the field near and underneath the surface including all secondaries…
CERN Course – Lecture 3October 28, 2005 – L. Pinsky
Modeling the Interaction of the Space Radiation in Spacecraft & Humans, and
Assessing the Risks on a Mission to Mars
46
Free Space GCR Environments at 1 AU1977 Solar Minimum (solid)1990 Solar Maximum (dashed)
Energy (MeV/amu)
Particle
Flu
ence
(#particles/cm
2-M
eV/a
mu-y
ear)
10-2 10-1 100 101 102 103 104 105 10610-3
10-2
10-1
100
101
102
103
104
105
106
Z=1
Z=2
3Z10
11Z20
21Z28
Courtesy of M. Clowdsley
CERN Course – Lecture 3October 28, 2005 – L. Pinsky
Modeling the Interaction of the Space Radiation in Spacecraft & Humans, and
Assessing the Risks on a Mission to Mars
47
Free Space Solar Particle Event Proton Spectra at 1 AU
Energy (MeV/amu)
Particle
Fluence
(#particles/cm
2-M
eV/a
mu)
10-2 10-1 100 101 102 103 104103
104
105
106
107
108
109
1010
1011
1012
Worst Case SPEFeb. 1956Aug. 1972Sept. 1989
Courtesy of M. Clowdsley
CERN Course – Lecture 3October 28, 2005 – L. Pinsky
Modeling the Interaction of the Space Radiation in Spacecraft & Humans, and
Assessing the Risks on a Mission to Mars
48
Lunar Surface GCR Environments
Energy (MeV/amu)
Particle
Fluence
(#particles/cm
2-M
eV/a
mu-y
ear)
10-2 10-1 100 101 102 103 104 105 10610-4
10-2
100
102
104
106
108
1010
Z=1
Z=0
Z=2
3Z1011Z20
21Z28
1977 Solar Minimum (solid)1990 Solar Maximum (dashed)
Courtesy of M. Clowdsley
CERN Course – Lecture 3October 28, 2005 – L. Pinsky
Modeling the Interaction of the Space Radiation in Spacecraft & Humans, and
Assessing the Risks on a Mission to Mars
49
Lunar Surface “Worst Case SPE” Environment
Energy (MeV/amu)
Particle
Fluence
(#particles/cm
2-M
eV/a
mu)
10-2 10-1 100 101 102 103 104102
103
104
105
106
107
108
109
1010
1011
Z=1
Z=0
Courtesy of M. Clowdsley
CERN Course – Lecture 3October 28, 2005 – L. Pinsky
Modeling the Interaction of the Space Radiation in Spacecraft & Humans, and
Assessing the Risks on a Mission to Mars
50
Dose Equivalent on Lunar Surface Due to GCR
Courtesy of M. Clowdsley
S p h e r e T h ic k n e s s ( g / c m2
)
An
nu
alB
FO
Do
seE
qui
vale
nt(c
Sv)
0 2 5 5 0 7 5 1 0 00
5
1 0
1 5
2 0
2 5
3 0
3 5
4 0A L 2 2 1 9 - 1 9 7 7 m in.P o ly e t h yle n e - 1 9 7 7 m in .H N a n o fib e rs - 1 9 7 7 m in .L iq u id H y d r o g e n - 1 9 7 7 m in .A L 2 2 1 9 - 1 9 9 0 m a x.P o ly e t h yle n e - 1 9 9 0 m a x.H N a n o fib e rs - 1 9 9 0 m a x.L iq u id H y d r o g e n - 1 9 9 0 m a x.
CERN Course – Lecture 3October 28, 2005 – L. Pinsky
Modeling the Interaction of the Space Radiation in Spacecraft & Humans, and
Assessing the Risks on a Mission to Mars
51
Modeling the Martian Surface Radiation Environment
CERN Course – Lecture 3October 28, 2005 – L. Pinsky
Modeling the Interaction of the Space Radiation in Spacecraft & Humans, and
Assessing the Risks on a Mission to Mars
52
Planetary Surface Material and Atmosphere
(Simonsen et al.)
Mars Induced Fields
GCR ion
Diffuseneutrons
High energyparticles
Courtesy of M. Clowdsley
CERN Course – Lecture 3October 28, 2005 – L. Pinsky
Modeling the Interaction of the Space Radiation in Spacecraft & Humans, and
Assessing the Risks on a Mission to Mars
53
Mars Surface Environment
Courtesy of M. Clowdsley
CERN Course – Lecture 3October 28, 2005 – L. Pinsky
Modeling the Interaction of the Space Radiation in Spacecraft & Humans, and
Assessing the Risks on a Mission to Mars
54
Mars Surface MappingCharged Ions – 1977 Solar Minimum
from Space Ionizing Radiation Environment and Shielding Tools (SIREST) web site http://sirest.larc.nasa.gov
Courtesy of M. Clowdsley
CERN Course – Lecture 3October 28, 2005 – L. Pinsky
Modeling the Interaction of the Space Radiation in Spacecraft & Humans, and
Assessing the Risks on a Mission to Mars
55
Mars Surface MappingNeutrons – 1977 Solar Minimum
from Space Ionizing Radiation Environment and Shielding Tools (SIREST) web site http://sirest.larc.nasa.gov
Courtesy of M. Clowdsley
CERN Course – Lecture 3October 28, 2005 – L. Pinsky
Modeling the Interaction of the Space Radiation in Spacecraft & Humans, and
Assessing the Risks on a Mission to Mars
56
Mars Surface MappingLow Energy Neutrons – 1977 Solar Minimum
from Space Ionizing Radiation Environment and Shielding Tools (SIREST) web site http://sirest.larc.nasa.gov
Courtesy of M. Clowdsley
CERN Course – Lecture 3October 28, 2005 – L. Pinsky
Modeling the Interaction of the Space Radiation in Spacecraft & Humans, and
Assessing the Risks on a Mission to Mars
57
Mars Surface GCR Environments
Energy (MeV/amu)
Particle
Fluence
(#particles/cm
2-M
eV/a
mu-y
ear)
10-2 10-1 100 101 102 103 104 105 10610-4
10-2
100
102
104
106
108
1010
Z=1
Z=0Z=2
3Z10
11Z20
21Z28
1977 Solar Minimum (solid)1990 Solar Maximum (dashed)
Courtesy of M. Clowdsley
CERN Course – Lecture 3October 28, 2005 – L. Pinsky
Modeling the Interaction of the Space Radiation in Spacecraft & Humans, and
Assessing the Risks on a Mission to Mars
58
Mars Surface Neutrons
Courtesy of M. Clowdsley
CERN Course – Lecture 3October 28, 2005 – L. Pinsky
Modeling the Interaction of the Space Radiation in Spacecraft & Humans, and
Assessing the Risks on a Mission to Mars
59
Mars Surface “Worst Case SPE” Environment
E n e rg y ( M e V / a m u )
Pa
rtic
leF
lue
nce
(#p
art
icle
s/cm
2
-Me
V/a
mu
)
1 0 - 2 1 0 - 1 1 0 0 1 0 1 1 0 2 1 0 3 1 0 41 0 0
1 01
1 0 2
1 0 3
1 04
1 0 5
1 0 6
1 07
1 0 8
1 0 9
Z = 1
Z = 0Z = 2
Courtesy of M. Clowdsley
CERN Course – Lecture 3October 28, 2005 – L. Pinsky
Modeling the Interaction of the Space Radiation in Spacecraft & Humans, and
Assessing the Risks on a Mission to Mars
60
Dose Equivalent on Mars Surface Due to GCR
S p h e r e T h ic k n e s s ( g / c m2
)
An
nu
alB
FO
Do
seE
qui
vale
nt(c
Sv)
0 2 5 5 0 7 5 1 0 00
5
1 0
1 5
2 0
2 5
3 0
3 5
4 0A L 2 2 1 9 - 1 9 7 7 m in .P oly e t h yle n e - 1 9 7 7 m in .H N a n o fib e rs - 1 9 7 7 m in .L iq u id H y d r o g e n - 1 9 7 7 m in .A L 2 2 1 9 - 1 9 9 0 m a x.P oly e t h yle n e - 1 9 9 0 m a x.H N a n o fib e rs - 1 9 9 0 m a x.L iq u id H y d r o g e n - 1 9 9 0 m a x.
Courtesy of M. Clowdsley
CERN Course – Lecture 3October 28, 2005 – L. Pinsky
Modeling the Interaction of the Space Radiation in Spacecraft & Humans, and
Assessing the Risks on a Mission to Mars
61
Summary and Conclusions
• SPE’s can probably be shielded against– …But only in “Storm-Shelters” or Protected Habitats
on planetary surfaces.
– Problematic during EVAs and in thinly shielded surroundings.
• GCR is more difficult to protect against in terms of keeping the Chronic Dose acceptable during a long mission, but enough shielding or a shorter mission could work…
CERN Course – Lecture 3October 28, 2005 – L. Pinsky
Modeling the Interaction of the Space Radiation in Spacecraft & Humans, and
Assessing the Risks on a Mission to Mars
62
Acknowledgements
N. Zapp (University of Houston) A. Ferrari (CERN & INFN-Milan)
J. Wilson (NASA -Langley) L. Townsend (Univ. of Tennessee)
M. Clowdsley (NASA-Langley) J. Barth (NASA-GSFC)
F. Cucinotta (NASA-JSC) S. Antiochos (NRL)
F. Balarini (INFN-Pavia) G.P. Zank (UC Riverside)
C. Cohen (Cal Tech) G. Reeves (LANL)
…And Many Others
European Community (EC contract # FI6R-CT-2003-508842) Italian Space Agency (ASI contract # I/R/320/02) NASA (Grants NAG8-1658 and NAG8-1901)
UH Institute for Space Systems Operations