Vladislav Petrov

Astronaut's organ doses inferred from measurements in a human phantom outside the international space station.

Abstract Reitz, G., Berger, T., Bilski, P., Facius, R., Hajek, M., Petrov, V., Puchalska, M., Zhou, D., Bossler, J., Akatov, Y., Shurshakov, V., Olko, P., Ptaszkiewicz, M., Bergmann, R., Fugger, M., Vana, N., Beaujean, R., Burmeister, S., Bartlett, D., Hager, L., Pálfalvi, J., Szabó, J., OSullivan, D., Kitamura, H., Uchihori, Y., Yasuda, N., Nagamatsu, A., Tawara, H., Benton, E., Gaza, R., McKeever, S., Sawakuchi, G., Yukihara, E., Cucinotta, F., Semones, E., Zapp, N., Miller, J. and Dettmann, J. Astronauts Organ Doses Inferred from Measurements in a Human Phantom Outside the International Space Station. Radiat. Res. 171, 225–235 (2009). Space radiation hazards are recognized as a key concern for human space flight. For long-term interplanetary missions, they constitute a potentially limiting factor since current protection limits for low-Earth orbit missions may be approached or even exceeded. In such a situation, an accurate risk assessment requires knowledge of equivalent doses in critical radiosensitive organs rather than only skin doses or ambient doses from area monitoring. To achieve this, the MATROSHKA experiment uses a human phantom torso equipped with dedicated detector systems. We measured for the first time the doses from the diverse components of ionizing space radiation at the surface and at different locations inside the phantom positioned outside the International Space Station, thereby simulating an extravehicular activity of an astronaut. The relationships between the skin and organ absorbed doses obtained in such an exposure show a steep gradient between the doses in the uppermost layer of the skin and the deep organs with a ratio close to 20. This decrease due to the body self-shielding and a concomitant increase of the radiation quality factor by 1.7 highlight the complexities of an adequate dosimetry of space radiation. The depth-dose distributions established by MATROSHKA serve as benchmarks for space radiation models and radiation transport calculations that are needed for mission planning.

The ALTCRISS project on board the International Space Station.

The Alteriss project aims to perform a long term survey of the radiation environment on board the International Space Station. Measurements are being performed with active and passive devices in different locations and orientations of the Russian segment of the station. The goal is to perform a detailed evaluation of the differences in particle fluence and nuclear composition due to different shielding material and attitude of the station. The Sileye-3/Alteino detector is used to identify nuclei up to Iron in the energy range above similar or equal to 60 MeV/n. Several passive dosimeters (TLDs, CR39) are also placed in the same location of Sileye-3 detector. Polyethylene shielding is periodically interposed in front of the detectors to evaluate the effectiveness of shielding on the nuclear component of the cosmic radiation. The project was submitted to ESA in reply to the AO in the Life and Physical Science of 2004 and data taking began in December 2005. Dosimeters and data cards are rotated every 6 months: up to now three launches of dosimeters and data cards have been performed and have been returned with the end of expedition 12 and 13

Radiation Environment on the International Space Station During the Solar Particle Events in March 2012

The Liulin-5 charged particle telescope observes the radiation characteristics in the spherical tissue-equivalent phantom of MATROSHKA-R international project on the International Space Station (ISS) since June 2007. In this paper attention is drawn to the results from the measurements of dose rate and particle flux increase during the Solar Energetic Particles Events (SPE) occurred in March 2012. During that SPE the solar particles penetrated at high geographic latitudes in the regions of the south and north Earth magnetic poles and at 3 < L they caused particle flux and dose rates increase in all three detectors of Liulin-5, located at 40, 60 and 165 mm depths along the phantom’s radius. The maximum flux at 40 mm depth observed outside the South Atlantic Anomaly (SAA) during that SPE reached 7.2 part/cm2.s and the dose rate reached 107.8 μGy/h on 07.03.2012, 13:06 UT at L=4. The additional absorbed dose received from SPE is approximately 180 μGy and additional dose equivalent- approximately 448 μSv. These additional exposures are comparable to the averaged daily absorbed dose and dose equivalent measured in the spherical phantom in ISS during quite radiation conditions. Discussed are the linear energy transfer spectra measured and quality factors obtained during and after the SPE. Compared are data from Liulin-5 and other particle detectors in space during the SPE.

Relative nuclear abundance from C to Fe and integrated flux inside the Russian part of the ISS with the Sileye-3/Alteino experiment

In this work we present data from the Sileye-3/Alteino detector on board the International Space Station (ISS), which was gathered following a recalibration after several years in orbit. We also measure the relative nuclei abundance and integratedflux,whichwerenormalizedtothesolarmodulationvaluesofAugust 2007. The measurements were made at different locations of the Russian part of the ISS. The relative nuclear abundances of C to Fe in relation to C, in an energyrangeabove � 60MeV/n,showshighlevelsofoddZparticlesinsidethe ISS and an under-abundance of C and O compared with the galactic spectrum, as presented by Simpson in 1983. In addition, the values of the integrated flux varies primarily according to location and detector orientation. An additional polyethylene shield also reduces the flux, although in a lower amount than changes in the orientation of the telescope. Data were taken as part of the ESA ALTCRISS project from late 2005 through to 2007.

Study of radiation conditions onboard the International space station by means of the Liulin-5 dosimeter

For estimating radiation risk in space flights it is necessary to determine radiation dose obtained by critical organs of a human body. For this purpose the experiments with human body models are carried out onboard spacecraft. These models represent phantoms equipped with passive and active radiation detectors which measure dose distributions at places of location of critical organs. The dosimetric Liulin-5 telescope is manufactured with using three silicon detectors for studying radiation conditions in the spherical tissue-equivalent phantom on the Russian segment of the International space station (ISS). The purpose of the experiment with Liulin-5 instrument is to study dynamics of the dose rate and particle flux in the phantom, as well as variations of radiation conditions on the ISS over long time intervals depending on a phase of the solar activity cycle, orbital parameters, and presence of solar energetic particles. The Liulin-5 dosimeter measures simultaneously the dose rate and fluxes of charged particles at three depths in the radial channel of the phantom, as well as the linear energy transfer. The paper presents the results of measurements of dose rate and particle fluxes caused by various radiation field components on the ISS during the period from June 2007 till December 2009.

Fault-related barriers for uranium transport

This contribution presents data on the long-term retentive ability of diverse mineral infill of hydraulically active faults in respect to radionuclides migrating within the vadose zone of crystalline massifs by the example of the vein-type Tulukuevskoe uranium deposit in SE Transbaikalia, Russia.

Uranium Mineralization in Fractured Welded Tuffs of the Krasnokamensk Area: Transfer from Ancient to Modern Oxidizing Conditions

The main aim of this contribution is to describe the primary controls of the hydrothermal mineralization, the preferential pathways for ancient and recent meteoric water infiltration, mineral-chemical modification of the wall rocks, and transformation of uranium mineralization in the context of redox front propagation through unsaturated fractured porous welded tuffs. The data on the veintype Tulukuevskoe uranium deposit in SE Transbaikalia, Russia are applied for modeling of uranium migration and deposition of secondary concentrations using quasi-stationary state approximation (QSSA) approach.

Lifetime total radiation risk of cosmonauts for orbital and interplanetary flights.

This paper presents results of calculations of total radiation risk for cosmonauts over their lifetimes and assessments of possible shortening of life expectancy on the basis of generalized doses calculated for cosmonauts after a long term interplanetary and orbital space missions on MIR station and International Space Station with the use of mathematical expressions coming from a model of change mortality rate of mammals after irradiation. Tumor risk assessments for cosmonauts over lifetime after flights are also given. Dependences of the delayed radiation consequences mentioned above on flight duration, spacecraft shielding thicknesses, solar activity and cosmonauts age are analyzed.

Study of dose distribution in a human body in international space station compartments with the tissue-equivalent spherical phantom

Space radiation is known to be key hazard of manned space mission. To estimate accurately radiation health risk detailed study of dose distribution inside human body by means of human phantom is conducted. In the space experiment MATROSHKA-R, the tissue-equivalent spherical phantom (32 kg mass, 35 cm diameter and 10 cm central spherical cave) made in Russia has been used on board the ISS for more than 8 years. Owing to the specially chosen phantom shape and size, the chord length distributions of the detector locations are attributed to self-shielding properties of the critical organs in a real human body. If compared with the anthropomorphic phantom Rando used inside and outside the ISS, the spherical phantom has lower mass, smaller size and requires less crew time for the detector installation/retrieval; its tissue-equivalent properties are closer to the standard human body tissue than the Rando-phantom material. Originally the spherical phantom was installed in the star board crew cabin of the ISS Service Module, then in the Piers-1, MIM-2 and MIM-1 modules of the ISS Russian segment, and finally in JAXA Kibo module. Total duration of the detector exposure is more than 1700 days in 8 sessions. In the first phase of the experiment with the spherical phantom, the dose measurements were realized with only passive detectors (thermoluminescent and solid-state track detectors). The detectors are placed inside the phantom along the axes of 20 containers and on the phantom outer surface in 32 pockets of the phantom jacket. After each session the passive detectors are returned to the ground. The results obtained show the dose difference on the phantom surface as much as a factor of 2, the highest dose being observed close to the outer wall of the compartment, and the lowest dose being in the opposite location along the phantom diameter. Maximum dose rate measured in the phantom is obviously due to the galactic cosmic ray (GCR) and Earth radiation belt contribution on the ISS trajectory. Minimum dose rate is caused mainly by the strongly penetrating GCR particles and is observed behind more than 5 g/cm2 tissue shielding. Critical organ doses, mean-tissue and effective doses of a crew member in the ISS compartments are also estimated with the spherical phantom data. The estimated effective dose rate is found to be from 10 to 15% lower than the averaged dose on the phantom surface as dependent on the attitude of the critical organs. The spherical phantom proved its effectiveness to measure the critical organ doses together with the effective dose in-flight and if supplied with active dosimeters can be recommended for future exploratory manned missions to monitor continuously the effective dose.

Uranium and Molybdenum transfer within the oxidized zone of uranium deposit

Total Dissolved Solids (ion composition), concentrations of some trace elements and pH-values determination results of vein-fractured water samples from the open pit of the Tulukuevskoe U-Mo deposit in acid volcanic rocks of Transbaikalia are presented. Rest upon obtained data it is possible to assume that in the southern part of the open pit a flat-lying ore-bearing untapped structure exists. An inverse relationship between the content of hydrocarbonate ions in veinfractured waters and concentration of uranium is presented.