12 research outputs found
THE DOSIS AND DOSIS 3D EXPERIMENTS ON-BOARD THE INTERNA- TIONAL SPACE STATION - CURRENT STATUS AND LATEST DATA FROM THE DOSTELS AS ACTIVE INSTRUMENTS
Besides the effects of the microgravity environment, and the psychological and psychosocial
problems encountered in confined spaces, radiation is the main health detriment for long duration
human space missions. The radiation environment encountered in space differs in nature
from that on earth, consisting mostly of high energetic ions from protons up to iron, resulting in
radiation levels far exceeding the ones encountered on earth for occupational radiation workers.
Accurate knowledge of the physical characteristics of the space radiation field in dependence
on the solar activity, the orbital parameters and the different shielding configurations of the
International Space Station ISS is therefore needed. For the investigation of the spatial and
temporal distribution of the radiation field inside the European COLUMBUS module the experiment
DOSIS (Dose Distribution Inside the ISS) under the lead of DLR has been launched
on July 15th 2009 with STS-127 to the ISS. The experimental package was transferred from the
Space Shuttle into COLUMBUS on July 18th. It consists of a combination of passive detector
packages (PDP) distributed at 11 locations inside the European Columbus Laboratory and two
active radiation detectors (Dosimetry Telescopes = DOSTELs) with a DDPU (DOSTEL Data
and Power Unit) in a Nomex pouch (DOSIS MAIN BOX) mounted at a fixed location beneath
the European Physiology Module rack (EPM) inside COLUMBUS. The active components of
the DOSIS experiment were operational from July 18th 2009 to June 16th 2011. After refurbishment
the hardware has been reactivated on May 15th 2012 as active part of the DOSIS
3D experiment and provides continuous data since this activation. The presentation will focus
on the latest results from the two DOSTEL instruments as absorbed dose, dose equivalent and
the related LET spectra gathered within the DOSIS (2009 - 2011) and DOSIS 3D (since 2012)
experiment. The CAU contributions to DOSIS and DOSIS 3D are financially supported by
BMWi under Grants 50WB0826, 50WB1026, 50WB1232 and 50WB1533
Modeling the variations of Dose Rate measured by RAD during the first MSL Martian year: 2012-2014
The Radiation Assessment Detector (RAD), on board Mars Science Laboratory's
(MSL) rover Curiosity, measures the {energy spectra} of both energetic charged
and neutral particles along with the radiation dose rate at the surface of
Mars. With these first-ever measurements on the Martian surface, RAD observed
several effects influencing the galactic cosmic ray (GCR) induced surface
radiation dose concurrently: [a] short-term diurnal variations of the Martian
atmospheric pressure caused by daily thermal tides, [b] long-term seasonal
pressure changes in the Martian atmosphere, and [c] the modulation of the
primary GCR flux by the heliospheric magnetic field, which correlates with
long-term solar activity and the rotation of the Sun. The RAD surface dose
measurements, along with the surface pressure data and the solar modulation
factor, are analysed and fitted to empirical models which quantitatively
demonstrate} how the long-term influences ([b] and [c]) are related to the
measured dose rates. {Correspondingly we can estimate dose rate and dose
equivalents under different solar modulations and different atmospheric
conditions, thus allowing empirical predictions of the Martian surface
radiation environment
Mars’ Surface Radiation Environment Measured with the Mars Science Laboratory’s Curiosity Rover
The Radiation Assessment Detector (RAD) on the Mars Science Laboratory’s Curiosity rover began making detailed measurements of the cosmic ray and energetic particle radiation environment on the surface of Mars on 7 August 2012. We report and discuss measurements of the absorbed dose and dose equivalent from galactic cosmic rays and solar energetic particles on the Martian surface for ~300 days of observations during the current solar maximum. These measurements provide insight into the radiation hazards associated with a human mission to the surface of Mars, and provide an anchor point to model the subsurface radiation environment, with implications for microbial survival times of any possible extant or past life, as well as for the preservation of potential organic biosignatures of the ancient Martian environment
Matroshka DOSTEL measurements onboard the International Space Station (ISS)
This paper presents the absorbed dose and dose equivalent rate measurements achieved with the DOSimetry TElescope
(DOSTEL) during the two Matroshka (MTR) experiment campaigns in 2004/2005 (MTR-1) and 2007/2008 (MTR-2B). The comparison
between the inside (MTR-2B) and outside (MTR-1) mission has shown that the shielding thickness provided by the International
Space Station (ISS) spacecraft hull has a minor effect on the radiation exposure caused by Galactic Cosmic Rays (GCR).
The exposure varies with the solar modulation of the GCR, too. Particles from Earth’s radiation belts are effectively shielded by
the spacecraft hull, and thus the contribution to the radiation exposure is lower for the inside measurement during MTR-2B. While
the MTR-DOSTEL absorbed dose rate shows a good agreement with passive detectors of the MTR experiment for the MTR-2B
mission phase, the MTR-1 absorbed dose rates from MTR-DOSTEL measurements are much lower than those obtained by a nearby
passive detector. Observed discrepancies between the MTR-DOSTEL measurements and the passive detectors located nearby
could be explained by the additional exposure to an enhanced flux of electrons trapped between L-parameter 2.5 and 3.5 caused by
solar storms in July 2004
THE DOSIS 3D PROJECT ONBOARD THE INTERNATIONAL SPACE STATION - ANALYSIS OF THE SOLAR PARTICLE EVENT IN SEPTEMBER 2017
Besides the effects of the microgravity environment, and the psychological and psychosocial
problems encountered in confined spaces, radiation is the main health detriment for long duration human space missions. The radiation environment encountered in space differs in nature
from that on earth, consisting mostly of high energetic ions from protons up to iron, resulting in
radiation levels far exceeding the ones encountered on earth for occupational radiation workers.
Accurate knowledge of the physical characteristics of the space radiation field in dependence on
the solar activity, the orbital parameters and the different shielding configurations of the International Space Station ISS is therefore needed. As a follow up to the DOSIS experiment (2009 -
2011) DOSIS 3D measures since May 2012 the spatial and temporal variations of the radiation
field in Columbus. The active part the DOSIS MAIN BOX thereby consist of two active radiation detectors (Dosimetry Telescopes = DOSTELs) with a DDPU (DOSTEL Data and Power
Unit) is mounted in a Nomex pouch at a fixed location in the bottom area of the European
Physiology Module rack (EPM). The temporal variation in dependence of ISS altitude and
solar cycle has been measured with the DOSTEL instruments since May 2012 covering thereby
already 6 years of continuous measurements in the frame of DOSIS 3D. Of special interest was
the first Solar Particle Event (SPE) (GLE 72) measured inside the Space Station within the
DOSIS 3D project in September 2017. This was the first event measured since 2012 inside the
ISS and in terms of exploration missions extremely important, since it was also measured in
Moon orbit and at the surface of Mars. The presentation will focus on the timeline of the event
observed inside Columbus and provide data for dose and relevant energy deposition spectra
and also show first comparisons with GEANT4 simulations. It will also provide comparison
with events observed with DOSTEL like instruments on space station MIR (1997) and on ISS
(2001). The CAU contributions to DOSIS and DOSIS 3D are financially supported by BMWiunder Grants 50WB0826, 50WB1026, 50WB1232 and 50WB1533
Matroshka DOSTEL measurements onboard the International Space Station (ISS)
This paper presents the absorbed dose and dose equivalent rate measurements achieved with the DOSimetry TElescope (DOSTEL) during the two Matroshka (MTR) experiment campaigns in 2004/2005 (MTR-1) and 2007/2008 (MTR-2B). The comparison between the inside (MTR-2B) and outside (MTR-1) mission has shown that the shielding thickness provided by the International Space Station (ISS) spacecraft hull has a minor effect on the radiation exposure caused by Galactic Cosmic Rays (GCR). The exposure varies with the solar modulation of the GCR, too. Particles from Earth’s radiation belts are effectively shielded by the spacecraft hull, and thus the contribution to the radiation exposure is lower for the inside measurement during MTR-2B. While the MTR-DOSTEL absorbed dose rate shows a good agreement with passive detectors of the MTR experiment for the MTR-2B mission phase, the MTR-1 absorbed dose rates from MTR-DOSTEL measurements are much lower than those obtained by a nearby passive detector. Observed discrepancies between the MTR-DOSTEL measurements and the passive detectors located nearby could be explained by the additional exposure to an enhanced flux of electrons trapped between L-parameter 2.5 and 3.5 caused by solar storms in July 2004
The Martian surface radiation environment – a comparison of models and MSL/RAD measurements
Context: The Radiation Assessment Detector (RAD) on the Mars Science Laboratory (MSL) has been measuring the radiation environment on the surface of Mars since August 6th 2012. MSL-RAD is the first instrument to provide detailed information about charged and neutral particle spectra and dose rates on the Martian surface, and one of the primary objectives of the RAD investigation is to help improve and validate current radiation transport models.
Aims: Applying different numerical transport models with boundary conditions derived from the MSL-RAD environment the goal of this work was to both provide predictions for the particle spectra and the radiation exposure on the Martian surface complementing the RAD sensitive range and, at the same time, validate the results with the experimental data, where applicable. Such validated models can be used to predict dose rates for future manned missions as well as for performing shield optimization studies.
Methods: Several particle transport models (GEANT4, PHITS, HZETRN/OLTARIS) were used to predict the particle flux and the corresponding radiation environment caused by galactic cosmic radiation on Mars. From the calculated particle spectra the dose rates on the surface are estimated.
Results: Calculations of particle spectra and dose rates induced by galactic cosmic radiation on the Martian surface are presented. Although good agreement is found in many cases for the different transport codes, GEANT4, PHITS, and HZETRN/OLTARIS, some models still show large, sometimes order of magnitude discrepancies in certain particle spectra. We have found that RAD data is helping to make better choices of input parameters and physical models. Elements of these validated models can be applied to more detailed studies on how the radiation environment is influenced by solar modulation, Martian atmosphere and soil, and changes due to the Martian seasonal pressure cycle. By extending the range of the calculated particle spectra with respect to the experimental data additional information about the radiation environment is gained, and the contribution of different particle species to the dose is estimated
The Martian surface radiation environment – a comparison of models and MSL/RAD measurements
Context: The Radiation Assessment Detector (RAD) on the Mars Science Laboratory (MSL) has been measuring the radiation environment on the surface of Mars since August 6th 2012. MSL-RAD is the first instrument to provide detailed information about charged and neutral particle spectra and dose rates on the Martian surface, and one of the primary objectives of the RAD investigation is to help improve and validate current radiation transport models.
Aims: Applying different numerical transport models with boundary conditions derived from the MSL-RAD environment the goal of this work was to both provide predictions for the particle spectra and the radiation exposure on the Martian surface complementing the RAD sensitive range and, at the same time, validate the results with the experimental data, where applicable. Such validated models can be used to predict dose rates for future manned missions as well as for performing shield optimization studies.
Methods: Several particle transport models (GEANT4, PHITS, HZETRN/OLTARIS) were used to predict the particle flux and the corresponding radiation environment caused by galactic cosmic radiation on Mars. From the calculated particle spectra the dose rates on the surface are estimated.
Results: Calculations of particle spectra and dose rates induced by galactic cosmic radiation on the Martian surface are presented. Although good agreement is found in many cases for the different transport codes, GEANT4, PHITS, and HZETRN/OLTARIS, some models still show large, sometimes order of magnitude discrepancies in certain particle spectra. We have found that RAD data is helping to make better choices of input parameters and physical models. Elements of these validated models can be applied to more detailed studies on how the radiation environment is influenced by solar modulation, Martian atmosphere and soil, and changes due to the Martian seasonal pressure cycle. By extending the range of the calculated particle spectra with respect to the experimental data additional information about the radiation environment is gained, and the contribution of different particle species to the dose is estimated
THE DOSIS 3D PROJECT ON-BOARD THE INTERNATIONAL SPACE STATION – STATUS AND SCIENCE OVERVIEW OF 8 YEARS OF MEASUREMENTS (2012 – 2020)
The radiation environment encountered in space differs in nature from that on Earth, consisting
mostly of highly energetic ions from protons up to iron, resulting in radiation levels far exceeding
the ones present on Earth for occupational radiation workers. Since the beginning of the space
era the radiation exposure during space missions has been monitored with various passive and
active radiation instruments. Also on-board the International Space Station (ISS) a number
of area monitoring devices provide data related to the spatial and temporal variation of the
radiation field in – and outside the ISS. The aim of the DOSIS 3D (2012 - ongoing) experiment
is the measurement of the radiation environment within the European Columbus Laboratory of
the ISS. These measurements are, on the one hand, performed with passive radiation detectors
mounted at eleven locations within Columbus for the determination of the spatial distribution
of the radiation field parameters and, on the other hand, with two active radiation detectors
(DOSTEL) mounted at a fixed position inside Columbus for the determination of the temporal
variation of the radiation field parameters. The talk will give an overview of the current results of the data evaluation performed for the passive and active radiation detectors for DOSIS 3D
in the years 2012 to 2020 and further focus on the work in progress for data comparison with
other passive and active radiation detector systems measuring on-board the ISS