radiation hazard to astronauts on low-earth orbit monika puchalska (on behalf of the polish...
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Radiation hazard to astronauts
on Low-Earth Orbit
Monika Puchalska (on behalf of the Polish MATROSHKA group)
Department of Radiation Physics and Dosimetry Institute of Nuclear Physics Polish Academy of Sciences
Previous experimentsinside ISS, 2001
1.1doseeffective
readoutdosemeter
effective dosequantity
Radiation hazard
The problem
What does the personal dosemeter measure?
?MTR-2a
MTR-1
Outline
1. Space project MATROSHKA 2. Methods3. Results4. Conclusions
International Contribution:20 Institutes for MATROSHKA
Science and Project Leader: G. Reitz, DLR
ESA Project
MATROSHKA project
Project on the International Space Station (ISS)
The main goal: evaluation of the radiation hazard outside and inside ISS
TTT
T QDwE Effective dose [Sv]
where:wT - tissue weighting factor
DT - average dose in organ/tissue
QT - Quality factor
Hiroshima & Nagasaki
MATROSHKA project
1. Phantom RANDO: tissue-equivalent material human skeleton embedded
inside2. Container simulating spacesuit
MATROSHKA project
TLDs
Total: 1631 measurement points 5373 TLDs(3140 TLDs from IFJ Kraków)
2.5 cm
3. Thermoluminescent detectors (TLDs)
MATROSHKA project
Methods
150 200 250 300 3500
2000
4000
6000
8000
Temperature [0C]
TL
sig
na
l
MTS-7
Thermoluminescent (TL) method
TL light emission
Dose
Methods
Numerical phantom – developed at IFJ
MATROSHKA - Results
3D dose distribution
MTR-1 – outside ISS
MTR-2a – inside ISS
Dose distribution
60% dose fall 30% dose fall from the most outer into the most inner measurement point
MATROSHKA - Results
MTR-1 – outside ISS MTR-2a – inside ISS
from the skin into the most outer measurement point
80% dose fall 10% dose fall
MATROSHKA - Results
Dose distribution
MTR-1 – outside ISS MTR-2a – inside ISS
+
MATROSHKA - Results
Evaluation of the organ doses
Spatial dose distribution Numerical phantom
MATROSHKA - Results
Kidney
Bladder
Small intestine
Stomach
Colon
Bone marrow
Heart
Liver
Lungs
Bones
Thyroid
Brain
Breast
Eye lens
Skin
0.0 0.2 0.4 0.6 0.8 1.0
Daily dose [mGy/day]
Outside ISS Inside ISS
Organ dose decreases for the inner structures 70% for outside exposure 20% for inside exposure
Inside comparing to outside exposure:• 5 times lower skin dose value 30% lower organ doses in
the inner part of the body
Evaluation of the organ doses
MTR-1 MTR-2a
mSv/day 0.08 0.60 mSv/day 0.07 0.45
MATROSHKA - Results
Evaluation of the effective dose
TTT
T QDwE
factor 1.3
MTR-1 – outside ISS MTR-2a – inside ISS
2.2doseeffective
dosemeterpersonalPersonal dosemeter readout: 1.30 mSv/dayEvaluated effective dose: 0.60 mSv/day
Reason:
low energy particles depositing their energy in the first few millimetres in the body whereas the important organs are located deeper and the personal dosemeter is located in front of the body
MATROSHKA - Results
Effective dose versus the personal dosemeter readout
MTR-1 - outside ISS
3.1doseeffective
dosemeterpersonalPersonal dosemeter readout: 0.58 mSv/dayEvaluated effective dose: 0.45 mSv/day
MTR-2a - inside ISS
Conclusions
o For the first time the radiation hazard to astronauts outside ISS was evaluated.
o Radiation hazard to astronauts on Low-Earth Orbit outside ISS is higher by a factor 1.3 than inside ISS.
o The personal dosimeter more than two times overestimates the real radiation hazard outside ISS and by 30% inside ISS.
Thank you for your attention