Space Radiation Hazards Space Radiation Hazards and Protectionand Protection

UND: Space Studies 410UND: Space Studies 410 Dr. Warren Jensen Dr. Warren Jensen Dr. Vadim Rygalov Dr. Vadim Rygalov NASA Ames Research Center: NASA Ames Research Center: Jon Rask Jon Rask Matt Allner Matt Allner

Bell RingerBell Ringer

1.1. & & are 2 types of are 2 types of radiation.radiation.

2.2. The Van Allen Belts & South Atlantic Anomaly The Van Allen Belts & South Atlantic Anomaly are both examples of sources of are both examples of sources of ..

3.3. Radiation can cause Radiation can cause & break & break ..

4.4. The most common way to protect astronauts The most common way to protect astronauts from radiation is with from radiation is with ..

Types of RadiationTypes of Radiation Ionizing RadiationIonizing Radiation

Removes electrons from atomsRemoves electrons from atoms

Leaves behind two electrically charged particles (ions)Leaves behind two electrically charged particles (ions)

Ionizing radiation causes changes in living tissueIonizing radiation causes changes in living tissue

Non-ionizing RadiationNon-ionizing Radiation Insufficient energy to remove electrons from atomsInsufficient energy to remove electrons from atoms

visible light, microwaves, or radio wavesvisible light, microwaves, or radio waves

Sources of Ionizing RadiationSources of Ionizing Radiation Galactic Cosmic Radiation (GCR)Galactic Cosmic Radiation (GCR)

Background, constantBackground, constant

Van Allen BeltsVan Allen Belts Contained in a Contained in a

specific regionspecific regionof spaceof space

South Atlantic South Atlantic AnomalyAnomaly

Solar Flares and Solar WindsSolar Flares and Solar Winds Solar Particle Solar Particle

Events (SPE)Events (SPE)IrregularIrregular

Predictable on Predictable on short noticeshort notice

Emits ionizing Emits ionizing & non-ionizing & non-ionizing radiationradiation

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Biologic Mechanisms of DamageBiologic Mechanisms of Damage Free Radical FormationFree Radical Formation

Cells incorrectly repair themselvesCells incorrectly repair themselves Formation of unstable molecules leading to indirect damageFormation of unstable molecules leading to indirect damage Water in cells is converted to hydrogen peroxideWater in cells is converted to hydrogen peroxide

DNA DamageDNA Damage Impaired cell function and production from loss of DNA controlImpaired cell function and production from loss of DNA control

Chromosomal DamageChromosomal Damage Cell replication abnormalities, birth defects, cancer Cell replication abnormalities, birth defects, cancer

DNA DamageDNA Damage CancerCancer

DNA BreaksDNA Breaks Different tissues are Different tissues are

more or less more or less sensitive to radiationsensitive to radiation

How often cells How often cells divide affects divide affects sensitivitysensitivity

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Protection / CountermeasuresProtection / CountermeasuresProtection by shielding is most commonProtection by shielding is most common

Materials for shielding will vary with the Materials for shielding will vary with the radiation type (mission definition)radiation type (mission definition)GCR - difficult due to high energyGCR - difficult due to high energy

5 m of lunar soil needed to equate Earth’s 5 m of lunar soil needed to equate Earth’s atmosphereatmosphere

SPE - easier due to decreased energy of particlesSPE - easier due to decreased energy of particles

1.1. Space Radiation Protection Space Radiation Protection Activity Activity

2. Yearly Radiation Exposure 2. Yearly Radiation Exposure WorksheetWorksheet

Today

Monday

Ticket InTicket In

Completed Cornell NotesCompleted Cornell Notes

Summary CompletedSummary Completed

Passes “Mr. Allner Test”Passes “Mr. Allner Test”

Ticket OutTicket Out

1.1. & & are 2 types of are 2 types of radiation.radiation.

2.2. The Van Allen Belts & South Atlantic Anomaly The Van Allen Belts & South Atlantic Anomaly are both examples of sources of are both examples of sources of ..

3.3. Radiation can cause Radiation can cause & break & break ..

4.4. The most common way to protect astronauts The most common way to protect astronauts from radiation is with from radiation is with ..

Bell RingerBell Ringer1.1. & & are 2 types of are 2 types of

radiation.radiation.

2.2. Does it matter what kind of radiation you are Does it matter what kind of radiation you are exposed to?exposed to?

3.3. Why should we care about our radiation exposure?Why should we care about our radiation exposure?

4.4. Name 1 thing you learned from the Space Name 1 thing you learned from the Space Radiation Activity.Radiation Activity.

How we measure radiation & exposuresHow we measure radiation & exposuresSI UnitsSI Units

RadioactivityRadioactivity Becquerel Becquerel 1 disintegration/sec1 disintegration/sec

Absorbed RadiationAbsorbed Radiation GreyGrey 1 Watt-Second/kg1 Watt-Second/kgDoseDose (J/kg) (J/kg)

Equivalent RadiationEquivalent Radiation SievertSievert 1 Watt-Second-kg1 Watt-Second-kgDoseDose (J-kg) (J-kg)

English UnitsEnglish Units RadioactivityRadioactivity CurieCurie 3.7*103.7*101010 Becquerel Becquerel

RRadiation adiation AAbsorbed bsorbed RadRad .01 Grey.01 GreyDDoseose

RRadiation adiation EEquivalent quivalent RemRem .01 Sievert.01 SievertMManan

Dose ~ EffectDose ~ Effect::

Dose, SvDose, Sv Probable EffectProbable Effect

0-0.50-0.5 No obvious effects; ~ minor blood changesNo obvious effects; ~ minor blood changes

0.5-10.5-1 RS in ~ 5-10% personnel; no serious disabilityRS in ~ 5-10% personnel; no serious disability

1-1.51-1.5 RS ~ 25% exposed personnelRS ~ 25% exposed personnel

1.5-21.5-2 RS ~ 50 % exposed personnelRS ~ 50 % exposed personnel

2-3.52-3.5 RS ~ 100% personnel; ~ 20% deathsRS ~ 100% personnel; ~ 20% deaths

3.5-53.5-5 RS; ~ 50% deathesRS; ~ 50% deathes

1010 Probably no survivorsProbably no survivors

Radiation Exposure LimitsRadiation Exposure Limits No threshold of exposure is safeNo threshold of exposure is safe

ALARA PrincipleALARA Principle AAs s LLow ow AAs s RReasonably easonably AAchievablechievable

LimitsLimits Terrestrial & Space: 50 mSv/yr.; Eye 15 mSv/yrTerrestrial & Space: 50 mSv/yr.; Eye 15 mSv/yr Space variables:Space variables:

Age at initial exposure, tissue type, genderAge at initial exposure, tissue type, genderCareer vs. 30 day exposureCareer vs. 30 day exposure

NASA ISS Astronaut NASA ISS Astronaut Chromosomal AberrationsChromosomal Aberrations

DeletionsDeletions

TranslocationsTranslocationsChromosome 3 & XChromosome 3 & XChromosomes 7 & 21Chromosomes 7 & 21Chromosomes 7,12, Chromosomes 7,12,

& 15& 15

Mutations from RadiationMutations from Radiation 1927 – Experiment creates fruit flies without wings1927 – Experiment creates fruit flies without wings

Trait passed through many generationsTrait passed through many generations

Most radiation induced mutations are recessiveMost radiation induced mutations are recessive

No hereditary effects in any mammals (hotly contested)No hereditary effects in any mammals (hotly contested) MiceMice Hiroshima or Nagasaki atomic bomb victimsHiroshima or Nagasaki atomic bomb victims

Plants have been modified through radiation exposurePlants have been modified through radiation exposure Swedish grain from a radiation induced strain resistant to coldSwedish grain from a radiation induced strain resistant to cold

Shield TypesShield Types Space bulk shieldingSpace bulk shielding

Aluminum works well, Aluminum works well, but has weight restrictionbut has weight restriction

Electromagnetic/ Electromagnetic/ Electrostatic shieldingElectrostatic shielding Not practical due to Not practical due to

power and weightpower and weight

Modified Clothing Modified Clothing (radiation shields)(radiation shields) DemronDemron Lead ApronLead Apron

Minimizing Radiation Exposure (cnt’d)Minimizing Radiation Exposure (cnt’d)

Shielding ConsiderationsShielding Considerations Acceptable risk/exposure limitsAcceptable risk/exposure limits

3% increase is currently discussed 3% increase is currently discussed Materials available (Water, fuel, etc.)Materials available (Water, fuel, etc.)

““Safe Haven” conceptSafe Haven” concept

Chemical radioprotectants (drugs)Chemical radioprotectants (drugs)

Mission planning (SAA avoidance)Mission planning (SAA avoidance)

Medical Therapies for treatment of radiation Medical Therapies for treatment of radiation exposuresexposures

Shielding Al/Equivalent:Shielding Al/Equivalent:

MaterialMaterial Thickness needed for 1 inch Al ShieldThickness needed for 1 inch Al Shield

PolyethylenePolyethylene 5.08 cm5.08 cm

H2OH2O 5.33 cm5.33 cm

AcrylicsAcrylics 5.84 cm5.84 cm

PbPb 2.79 cm2.79 cm

AlAl 2.54 cm2.54 cm

ReferencesReferences1. http://www.radshield.com/faq_qa.asp2. http://library.thinkquest.org/3471/radiation_effects_body.ht

ml3. http://searchcio-midmarket.techtarget.com/sDefinition/0,,sid

183_gci528813,00.html4. http://en.wikipedia.org/wiki/Inverse-square_law 5. http://www.nasa.gov/mission_pages/station/science/experim

ents/Chromosome.html

6. http://www.ias.u-psud.fr/medoc/presentations_solaires/Young/c2cme.mpeg

7.7. Choppin, Gregory, et al. Choppin, Gregory, et al. Radiochemistry & Nuclear Radiochemistry & Nuclear ChemistryChemistry. 3. 3rdrd edition. Woburn, MA:Butterworth- edition. Woburn, MA:Butterworth-Heinemann ©2002Heinemann ©2002

Electromagnetic RadiationElectromagnetic Radiation

Radiation TypeRadiation Type Wave length, mWave length, m

- rays- rays 1010-14-14 – 10 – 10-12-12

X – raysX – rays 1010-12-12 – 10 – 10-8-8

UltravioletUltraviolet 1010-8-8 – 10 – 10-7-7

Visible lightVisible light ~ 10~ 10-7-7

InfraredInfrared 1010-6-6 – 10 – 10-3-3

Radio wavesRadio waves 1010-3-3 – 10 – 10+4+4

Non-ionizing RadiationNon-ionizing Radiation

Ionizing RadiationIonizing Radiation

The penetration of radiation The penetration of radiation depends on mass.depends on mass.-radiation (zero mass) -radiation (zero mass)

penetrates much further thanpenetrates much further than

-radiation, -radiation, which penetrates much further thanwhich penetrates much further than

-radiation (helium)-radiation (helium)

Penetrating RadiationPenetrating Radiation

Minimizing Radiation ExposureMinimizing Radiation Exposure TimeTime

How many times are you How many times are you exposed?exposed?OnceOnceTwiceTwiceEvery day for 30 yearsEvery day for 30 years

How long are you How long are you exposed?exposed?MinutesMinutesYearsYears

DistanceDistance Further is betterFurther is better

Exposure drops Exposure drops exponentially with exponentially with increasing distanceincreasing distance

Minimizing Radiation Exposure (cnt’d)Minimizing Radiation Exposure (cnt’d) SourceSource

Half life/ActivityHalf life/Activity EmissionEmission

Alpha ParticleAlpha ParticleBeta ParticleBeta ParticleElectromagnetic Electromagnetic

DistanceDistance Further is betterFurther is better Exposure drops exponentially with increasing distanceExposure drops exponentially with increasing distance

Shield TypesShield Types Chemical Radioprotection (CRP):Chemical Radioprotection (CRP):

Aminopropyl-aminoethyl thiophosphoric acid Aminopropyl-aminoethyl thiophosphoric acid (APAETF) (APAETF) have to be rapidly absorbed & distributed to have to be rapidly absorbed & distributed to

the tissues to avoid negative side effectsthe tissues to avoid negative side effects

Prussian BluePrussian Blue

DiethylenetriaminepentaacetateDiethylenetriaminepentaacetateRestricted use, no kids, Restricted use, no kids,

or pregnant womenor pregnant women

Shield TypesShield Types Space bulk shieldingSpace bulk shielding

Aluminum works well, but has weight Aluminum works well, but has weight restrictionrestriction

Electromagnetic/Electrostatic shieldingElectromagnetic/Electrostatic shieldingNot practical due to power and weight Not practical due to power and weight

requirementsrequirements

Clothing modified to act as radiation shieldsClothing modified to act as radiation shields DemronDemron Lead ApronLead Apron

Radiation Shielding:Radiation Shielding:Shielding Effect for Al

y (protons) = 39.511e-0.0707x

R2 = 0.9835

0

10

20

30

40

50

60

0 20 40

Thickness, cm

Do

se E

qu

ival

ent,

rem

/yea

r

Heavy Ions

Protons

Neutrons

Sec Particles

Expon. (Protons)

Quality Factor QQuality Factor Q::RadiationRadiation QQ OccuranceOccurance

X – raysX – rays 11 Belts, Solar radiationBelts, Solar radiation

5 MeV 5 MeV -rays-rays 0.50.5 Belts, Solar radiationBelts, Solar radiation

1 MeV 1 MeV -rays-rays 0.70.7 Belts, Solar radiationBelts, Solar radiation

200 keV 200 keV -rays-rays 1.01.0 Belts, Solar radiationBelts, Solar radiation

ElectronsElectrons 1.01.0 Radiation beltsRadiation belts

ProtonsProtons 2.0-10.02.0-10.0 CR, inner beltsCR, inner belts

NeutronsNeutrons 2-102-10 Close to Earth, Sun, planetsClose to Earth, Sun, planets

-particles-particles 10-2010-20 Cosmic Radiation (CR)Cosmic Radiation (CR)

Heavy particlesHeavy particles ~,~,2020 Cosmic Radiation (CR)Cosmic Radiation (CR)

Health EffectsHealth Effects Separated into acute (early) and delayed effectsSeparated into acute (early) and delayed effects

Dose is a useful term in evaluating acute effects Dose is a useful term in evaluating acute effects and risk of delayed effectsand risk of delayed effects There is no “safe” dose of ionizing radiationThere is no “safe” dose of ionizing radiation The younger children are, the higher the risk of RSThe younger children are, the higher the risk of RS

Dose is dependent on orbitDose is dependent on orbit AltitudeAltitude InclinationInclination

Acute (early) EffectsAcute (early) Effects 100-200 rem: minimal symptoms100-200 rem: minimal symptoms

Rapidly replicating and productive cells are most Rapidly replicating and productive cells are most vulnerablevulnerable Bone marrow (blood components)Bone marrow (blood components) Intestinal liningIntestinal lining Hair folliclesHair follicles Growing childrenGrowing children

Characteristic symptoms of radiation sickness Characteristic symptoms of radiation sickness (latent period of 2 weeks)(latent period of 2 weeks)

Radiation Sickness (RS) Symptoms:Radiation Sickness (RS) Symptoms: Acute RS (within a few days):Acute RS (within a few days):

- nausea- nausea- vomiting- vomiting- discomfort- discomfort- loss of appetite- loss of appetite- fatigue- fatigue

Delayed RS (many years after):Delayed RS (many years after):- cancer (lung, breast, digestive system)- cancer (lung, breast, digestive system)- leukemia- leukemia

Fatal cancer: + 2-5% for each 0.5 SvFatal cancer: + 2-5% for each 0.5 Sv

Minimizing Radiation Exposure (cnt’d)Minimizing Radiation Exposure (cnt’d) ShieldingShielding

TypesTypesElectromagneticElectromagnetic

Planetary FieldsPlanetary Fields Artificially created Artificially created

FieldsFields Faraday CageFaraday Cage

PhysicalPhysical LeadLead AluminumAluminum WaterWater Demron FabricDemron Fabric

Minimizing Radiation ExposureMinimizing Radiation Exposure SourceSource

EmissionEmissionAlpha ParticleAlpha ParticleBeta ParticleBeta ParticleElectromagneticElectromagnetic

X-RayX-Ray Ultra Violet Ultra Violet

Half life/ActivityHalf life/ActivityShort Half LifeShort Half LifeLong Half LifeLong Half Life

DNA DamageDNA Damage

Damage can be:Damage can be:HarmfulHarmful

CancerCancerSickle Cell AnemiaSickle Cell Anemia

No EffectNo Effect

BeneficialBeneficialO bloodtypeO bloodtype

DNA DamageDNA Damage

Damage can be:Damage can be: HarmfulHarmful

CancerCancer Sickle Cell AnemiaSickle Cell Anemia DNA BreaksDNA Breaks

No EffectNo Effect

BeneficialBeneficial O bloodtypeO bloodtype

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