Research Article

DOSIS & DOSIS 3D: radiation measurements with the DOSTEL instruments onboard the Columbus Laboratory of the ISS in the years 2009–2016

¹ German Aerospace Center (DLR), Institute of Aerospace Medicine, Linder Höhe, 51147 Köln, Germany
² Christian Albrechts Universität zu Kiel (CAU), Christian-Albrechts-Platz, 24118 Kiel, Germany
³ Institute of Nuclear Physics Polish Academy of Sciences (IFJ), PL-31342 Krakow, Poland
⁴ International Atomic Energy Agency (IAEA), Division of Radiation, Transport and Waste Safety, 1400 Vienna, Austria
⁵ Technische Universität Wien, Atominstitut (ATI), Stadionallee 2, 1020 Vienna, Austria
⁶ EGB MedAustron, Marie-Curie-Straße 5, 2700 Wiener Neustadt, Austria
⁷ Centre for Energy Research, (MTA EK), Konkoly Thege ut 29-33, 1121 Budapest, Hungary
⁸ Nuclear Physics Institute of the CAS (NPI), Department of Radiation Dosimetry, Na Truhlarce 39/64, 180 00 Prague, Czech Republic
⁹ Belgian Nuclear Research Center (SCK•CEN), Boeretang 200, 2400 Mol, Belgium
¹⁰ NASA, Space Radiation Analysis Group (NASA/SRAG), Houston, TX 77058, USA
¹¹ Leidos, Exploration & Mission Support, 2400 NASA Pkwy, Houston, TX 77058, USA
¹² Physics Department, Oklahoma State University (OSU), Stillwater, OK 74078, USA
¹³ National Institute of Radiological Sciences (NIRS), National Institutes for Quantum and Radiological Science and Technology (QST), 4-9-1 Anagawa, Inage, Chiba 263-8555, Japan
¹⁴ OHB System AG, Universitätsallee 27-29, 28359 Bremen, Germany

^* Corresponding author: thomas.berger@dlr.de

Received: 2 November 2016
Accepted: 30 January 2017

Abstract

The natural radiation environment in Low Earth Orbit (LEO) differs significantly in composition and energy from that found on Earth. The space radiation field consists of high energetic protons and heavier ions from Galactic Cosmic Radiation (GCR), as well as of protons and electrons trapped in the Earth’s radiation belts (Van Allen belts). Protons and some heavier particles ejected in occasional Solar Particle Events (SPEs) might in addition contribute to the radiation exposure in LEO. All sources of radiation are modulated by the solar cycle. During solar maximum conditions SPEs occur more frequently with higher particle intensities. Since the radiation exposure in LEO exceeds exposure limits for radiation workers on Earth, the radiation exposure in space has been recognized as a main health concern for humans in space missions from the beginning of the space age on. Monitoring of the radiation environment is therefore an inevitable task in human spaceflight. Since mission profiles are always different and each spacecraft provides different shielding distributions, modifying the radiation environment measurements needs to be done for each mission. The experiments “Dose Distribution within the ISS (DOSIS)” (2009–2011) and “Dose Distribution within the ISS 3D (DOSIS 3D)” (2012–onwards) onboard the Columbus Laboratory of the International Space Station (ISS) use a detector suite consisting of two silicon detector telescopes (DOSimetry TELescope = DOSTEL) and passive radiation detector packages (PDP) and are designed for the determination of the temporal and spatial variation of the radiation environment. With the DOSTEL instruments’ changes of the radiation composition and the related exposure levels in dependence of the solar cycle, the altitude of the ISS and the influence of attitude changes of the ISS during Space Shuttle dockings inside the Columbus Laboratory have been monitored. The absorbed doses measured at the end of May 2016 reached up to 286 μGy/day with dose equivalent values of 647 μSv/day.