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
The problem
Radiation hazard
quantity
effective dose
MTR-1 Previous experiments
MTR-2a
What does the personal
dosemeter measure?
inside ISS, 2001
dosemeter readout
 1.1
effective dose
Outline
1. Space project MATROSHKA
2. Methods
3. Results
4. Conclusions
MATROSHKA project
ESA Project
Science and Project Leader: G. Reitz, DLR
International Contribution:
20 Institutes for MATROSHKA
Project on the International Space Station (ISS)
MATROSHKA project
The main goal: evaluation of the radiation
hazard outside and inside ISS
Effective dose [Sv]
E   wT DT QT
T
Hiroshima & Nagasaki
where: wT - tissue weighting factor
DT - average dose in organ/tissue
QT - Quality factor
MATROSHKA project
1. Phantom RANDO:
 tissue-equivalent material
 human skeleton embedded inside
2. Container simulating spacesuit
MATROSHKA project
3. Thermoluminescent detectors (TLDs)
TLDs
2.5 cm
Total:
 1631 measurement points
 5373 TLDs
(3140 TLDs from IFJ Kraków)
Methods
 Thermoluminescent (TL) method
8000
MTS-7
TL light emission
TL signal
6000
4000
2000
Dose
0
150
200
250
300
0
Temperature [ C]
350
Methods
 Numerical phantom – developed at IFJ
MATROSHKA - Results
 3D dose distribution
MTR-1 – outside ISS
MTR-2a – inside ISS
MATROSHKA - Results
 Dose distribution
MTR-2a – inside ISS
0.5
0.5
0.4
0.4
Daily dose [mGy/d]
Daily dose [mGy/d]
MTR-1 – outside ISS
0.3
0.2
0.3
0.2
0.1
0.1
0
20
40
60
80
Min. distance from the phantom edge [mm]
100
120
0
20
40
60
80
Min. distance from the phantom edge [mm]
 60% dose fall
 30% dose fall
from the most outer into the most inner measurement point
100
120
MATROSHKA - Results
 Dose distribution
MTR-1 – outside ISS
MTR-2a – inside ISS
2.5
2.5
Daily dose [mGy/day]
Daily dose [mGy/day]
skin dose
2.0
0.5
2.0
0.5
skin dose
0.0
0.0
0
20
40
60
80
Min. distance from the phantom edge [mm]
100
120
0
20
40
60
80
Min. distance from the phantom edge [mm]
 10% dose fall
 80% dose fall
from the skin into the most outer measurement point
100
120
MATROSHKA - Results
 Evaluation of the organ doses
Spatial dose distribution
Numerical phantom
+
MATROSHKA - Results
 Evaluation of the organ doses
 Organ dose decreases for the
inner structures
Skin
Eye lens
Breast
Outside ISS
Inside ISS
Brain
•  70% for outside exposure
•  20% for inside exposure
Thyroid
Bones
Lungs
Liver
Heart
 Inside comparing to outside
exposure:
Bone marrow
Colon
Stomach
Small intestine
Bladder
Kidney
0.0
0.2
0.4
0.6
Daily dose [mGy/day]
0.8
1.0
• 5 times lower skin dose value
•  30% lower organ doses in the
inner part of the body
MATROSHKA - Results
 Evaluation of the effective dose
E   wT DT QT
T
MTR-1 – outside ISS
MTR-2a – inside ISS
MTR-1
0.60  0.08 mSv/day
MTR-2a
0.45  0.07 mSv/day
factor 1.3
MATROSHKA - Results
 Effective dose versus the personal dosemeter readout
MTR-1 - outside ISS
Evaluated effective dose:
0.60 mSv/day
Personal dosemeter readout: 1.30 mSv/day
personal dosemeter
 2.2
effective dose
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
MTR-2a - inside ISS
Evaluated effective dose:
0.45 mSv/day
Personal dosemeter readout: 0.58 mSv/day
personal dosemeter
 1.3
effective dose
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