radiation physiology and effectsspacecraft.ssl.umd.edu/.../697s13/697s13l06.radiation1.pdf · 2013....

Radiation Physiology and EffectsENAE 697 - Space Human Factors and Life Support

U N I V E R S I T Y O FMARYLAND

Radiation Physiology and Effects• Sources and types of space radiation• Effects of radiation• Shielding approaches

1

© 2011 David L. Akin - All rights reservedhttp://spacecraft.ssl.umd.edu

http://spacecraft.ssl.umd.edu

http://spacecraft.ssl.umd.edu



The Origin of a Class X1 Solar Flare

2



The Earth’s Magnetic Field

Ref: V. L. Pisacane and R. C. Moore, Fundamentals of Space Systems Oxford University Press, 1994

3



The Van Allen Radiation Belts


4



Cross-section of Van Allen Radiation Belts


5



Electron Flux in Low Earth Orbit


6



Heavy Ion Flux

Ref: Neville J. Barter, ed., TRW Space Data, TRW Space and Electronics Group, 1999

Background Solar Flare

7



Radiation Units• Dose D= absorbed radiation

• Dose equivalent H= effective absorbed radiation

• LET = Linear Energy Transfer <KeV/µ m>

8

1 Gray = 1Joule

kg= 100 rad = 10, 000

ergs

gm

1 Sievert = 1Joule

kg= 100 rem = 10, 000

ergs

gm

H = DQ rem = RBE × rad



Radiation Quality Factor

9

Radiation QX-rays 1

5 MeV !-rays 0.51 MeV !-rays 0.7

200 KeV !-rays 1.0Electrons 1.0Protons 2-10

Neutrons 2-10"-particles 10-20

GCR 20+



Radiation in Free Space

10



Radiation Dose vs. Orbital Altitude

Ref: Neville J. Barter, ed., TRW Space Data, TRW Space and Electronics Group, 1999

300 mil (7.6 mm) Al shielding

11



Dosage Rates from Oct/Nov 2003 SPE

12



SPEs in Solar Cycles 19, 20, and 21

13



GCR Constituent Species

14



Solar Max/Min GCR Proton Flux Ratio

15



Radiation Damage to DNA

16



Symptomology of Acute Radiation Exposure• “Radiation sickness”: headache, dizziness, malaise,

nausea, vomiting, diarrhea, lowered RBC and WBC counts, irritability, insomnia

• 50 rem (0.5 Sv)– Mild symptoms, mostly on first day– ~100% survival

• 100-200 rem (1-2 Sv)– Increase in severity and duration– 70% incidence of vomiting at 200 rem– 25%-35% drop in blood cell production– Mild bleeding, fever, and infection in 4-5 weeks

17



Symptomology of Acute Radiation Exposure• 200-350 rem (2-3.5 Sv)

– Earlier and more severe symptoms– Moderate bleeding, fever, infection, and diarrhea at 4-5

weeks• 350-550 rem (3.5-5.5 Sv)

– Severe symptoms– Severe and prolonged vomiting - electrolyte imbalances– 50-90% mortality from damage to hematopoietic system if

untreated

18



Symptomology of Acute Radiation Exposure• 550-750 rem (5.5-7.5 Sv)

– Severe vomiting and nausea on first day– Total destruction of blood-forming organs– Untreated survival time 2-3 weeks

• 750-1000 rem (7.5-10 Sv)– Survival time ~2 weeks– Severe nausea and vomiting over first three days– 75% prostrate by end of first week

• 1000-2000 rem (10-20 Sv)– Severe nausea and vomiting in 30 minutes

• 4500 rem (45 Sv)– Survival time as short as 32 hrs - 100% in one week

19



Long-Term Effects of Radiation Exposure

• Radiation carcinogenesis– Function of exposure, dosage, LET of radiation

• Radiation mutagenesis– Mutations in offspring– Mouse experiments show doubling in mutation rate at

15-30 rad (acute), 100 rad (chronic) exposures

• Radiation-induced cataracts– Observed correlation at 200 rad (acute), 550 rad (chronic)– Evidence of low onset (25 rad) at high LET

20



Radiation Carcinogenesis• Manifestations

– Myelocytic leukemia– Cancer of breast, lung, thyroid, and bowel

• Latency in atomic bomb survivors– Leukemia: mean 14 yrs, range 5-20 years– All other cancers: mean 25 years

• Overall marginal cancer risk– 70-165 deaths/million people/rem/year– 100,000 people exposed to 10 rem (acute) -> 800

additional deaths (20,000 natural cancer deaths) - 4%

21



NASA Radiation Dose Limits

22



Density of Common Shielding Materials

23

0

2

4

6

8

10

12

Polyethyle

neWate

rGr/E

p

Acrylic

s

AluminumLea

d



Comparative Thickness of Shields (Al=1)

24

0

1

2

3

Polyethyle

neWate

rGr/E

p

Acrylic

s

AluminumLea

d



Comparative Mass for Shielding (Al=1)

25

0

1

2

3

4

5

Polyeth

ylene

Water

Gr/Ep

Acrylics

Aluminu

mLe

ad



Effective Dose Based on Shielding

26

Francis A. Cucinotta, Myung-Hee Y. Kim, and Lei Ren, Managing Lunar and Mars Mission Radiation Risks Part I: Cancer Risks, Uncertainties, and Shielding Effectiveness NASA/TP-2005-213164, July, 2005



Shielding Materials Effect on GCR

27

–, Human Integration Design Handbook, NASA SP-2010-3407, Jan. 2010



Lunar Regolith Shielding for SPE

28




Mars Regolith Shielding Effectiveness

29




Radiation Exposure Induced Deaths

30

Francis A. Cucinotta, Myung-Hee Y. Kim, and Lei Ren, Managing Lunar and Mars Mission Radiation Risks Part I: Cancer Risks, Uncertainties, and Shielding Effectiveness NASA/TP-2005-213164, July, 2005

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(%) Fatal Cancer Risk0 3 6 9 12 15

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radiation physiology and effectsspacecraft.ssl.umd.edu/.../697s13/697s13l06.radiation1.pdf · 2013....

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