REDUCING RADIATION RISK IN SPACE The Matroshka project

Abstract

With longer missions, the radiation safety of astronauts has become one of the most important areas of study for biomedicine in manned spaceflights. Even after nearly five decades of spaceflight, sending humans into space still has inherent and significant risks. The exploration of space exposes astronauts to a hostile environment that, if not properly mitigated, could have some serious health impacts. Exposure to cosmic radiation is one risk that can be reduced with careful mission planning and constructive measures, such as providing radiation shelters. However, this risk cannot be completely avoided, because of the extremely high energies of these particles and their high penetration depth in matter. The exact determination of radiation dose in space is a demanding and challenging task, which is tackled in a close cooperation of all the International Space Station (ISS) partners. The daily dose rates – up to a few hundred of microsieverts (μSv) in low Earth orbit – are among the highest reached for humans working in a natural radiation environment. Various research activities are trying to understand better the interactions of the space radiation environment with the human body, aiming for a better system of radiation risk estimation for future exploration missions – such as going to the Moon or to Mars. Currently, the biggest radiation experiment is Matroshka. Operating on the ISS since January 2004, Matroshka is designed to show the radiation distribution in the human body under different shielding conditions, inside and outside the ISS. The key part of the Matroshka facility is the human ‘phantom’, equipped with thousands of radiation sensors, which is helping scientists to understand more precisely the dose and particle distribution in a human body for an improved radiation risk assessment.