G. Reitz
German Aerospace Center, Aerospace Medicine, Radiation Biology Division,
51147 Koeln, Germany, phone: ++49 2203 601 3137, email:guenther.reitz@dlr.de
MATROSHKA is designed to allow studies of the depth dose distribution of the different components of the orbital radiation field at different sides of the organs, occurring in men being exposed during an Extra Vehicular Activity (EVA). The MATROSHKA facility basically consists of a human phantom, which is housed in a sealed container providing structural support and fixation of the phantom and protection against e.g. space vacuum, space debris and solar UV (Fig.1). The container, which is a Carbon Fiber Reinforced Plastic( CFRP) monolith structure, as well as the phantom will be mounted to a base structure, which hosts the facility and most of the radiation detectors electronics. The MATROSKA electronic consists of a power conditioning unit to receive, convert and distribute filtered and regulated power to its subsystems and to the detector electronics, a data handling module to communicate with the detectors and the Russian Service Module and for temporally data storage of housekeeping data, a memory module as temporary buffer for scientific date and a sensor module managing information of the housekeeping sensors.
Figure 1 MATROSHKA overview.
The phantom consists of commercial phantom parts. It is built up by 32 slices composed of natural bones, embedded in tissue equivalent plastics of different density for tissue and lung. The phantom provides spaces for the accommodation of active and passive radiation detector sensors and of housekeeping sensors like temperature and pressure. It carries a Nomex poncho that provide pockets for carrying passive detectors to allow for skin measurements.
MATROSHKA will be launched early 2003 and exposed during 1 year outside the Russian Service Module. Once activated MATROSHKA will provide permanently house keeping and scientific data. The amount of data generated is 5.1 MB per day which will be stored in the mass memory of an onboard computer. Under nominal operations, data are downlinked each day, but this data amount is limited to 5 MB a week. Further measurements are planned inside the Service Module with MATROSHKA when it is brought back after the outside exposure.
MATROSHKA uses different sensors which allow measurements of dose rate, particle flux and spectra and linear energy spectra. Various types of thermoluminescence detectors (TLDs) are distributed throughout the phantom body and also at the phantom surface. In addition, it is planned to integrate TLDs in the outer layer of the Multi-layer Insulation. Five passive detector packages (80x40x25 mm) are located at sides of organs of interest inside the phantom ( brain, lung kidney, stomach, intestine) and one is located at top of the phantom head. They are built up from plastic nuclear track detectors (PNTD) like CR39, polycarbonate and cellulose nitrate and personal dosimeter packages. The latter ones consists of CR-39 detectors combined with three converter foils and of Makrofol detectors each welded in a radon-tight aluminum/polyethylene pouch and packed inside an albedo dosimeter capsule consisting of boron loaded polyurethane. In front of the phantom body a tissue equivalent proportional counter (TEPC) is mounted which uses a cylindrical low pressure ionization chamber surrounded by 1.9 mm tissue equivalent A-100 plastic material. On top of the phantom head a dosimetry telescope (DOSTEL) sensor is mounted using three silicon detectors in a telescope arrangement. Inside the phantom five silicon/scintillator detectors (SSDs) sensors (36x26x25 mm) are located at sites of the brain, lung, kidney, stomach and intestine. Each detector consists of a plastic scintillator cube surrounded by six silicon detectors acting as anticoincidence detectors. The electronics for the two latter instruments are located in the base structure in the electronics module, which also houses the High-LET Radiation spectrometer (HiLRS). The HiLRS is composed of solid state microelectronics that measure the energy deposited (in terms of pulse-height spectra) when energetic charged particles traverse p-n junctions having dimensions comparable to biological cells.
Following investigators and labs are involved in the investigations: : Dr. Bill Atwell, Boeing, Houston, USA; Dr. G. Badhwar, NASA, Johnson Spaceflight Center, Houston, USA; Dr. M. Luszik-Bhadra, PTB, Braunschweig, Germany; Dr. R. Beaujean, University Kiel, Germany; Dr. S. Deme, KFKI Atomic Energy, Research Institute, Budapest; Prof. W. Heinrich, Universität GH Siegen, Germany; Dr. J. Miller, LBL, Berkeley, California, USA; Dr. P. Olko, Institute of Nuclear Physics, Krakow, Poland; Dr. Petrov, IBMP, Moscow, Russia; Dr. E.G. Stassinopoulos, NASA, Goddard Space Flight Center, USA.