Planetary Group Seminar: Radiation protection today in space and on ground - what is the challenge? (A. Hirn)

Human missions to cislunar space, capturing an asteroid, Moon village and the journey to Mars in the 2030's: examples for how humans plan to extend human presence in space beyond low Earth orbit in the following decades. Radiation protection is of prime importance for these projects to become reality. Right now, despite of all our knowledge and experiences gained, the question of whether astronauts could make a round trip to Mars without long-term radiation health effects is still open. Instrumentation and methods used in the physics of ionizing radiations developed a lot since Wilhelm Röntgen discovered the X-rays in 1895. We also learned that ionizing radiation is a natural part of our environment and that the human body is also a radioactive source itself. However, due to the harmful biological effects, exposure to ionizing radiation shall be kept as low as reasonably achievable or it shall be justified e.g. in the case of cancer treatment. By now, the physical interactions between ionizing radiation and matter are well understood; there are huge databases available for cross sections of different nuclear interactions for a wide energy range. There are also several types of radiation detectors and dosimeters sensitive to different components of the radiation field. But even if we have all the physics data we need (actually we do not), how can we use them for estimating the risks associated with space radiation? Do we fully understand the underlying biological processes? Is it possible to define simple, reliable operational quantities for the astronauts performing interplanetary flights in the coming decades? In my talk I am going to make an attempt to highlight the questions still to be answered and the processes to be understood in the field of radiation protection.