Free Astronomy Magazine September-October 2019

ASTRONAUTICS 41 SEPTEMBER-OCTOBER 2019 T oday, we have the technological knowledge necessary to make long journeys within the inner Solar Sys- tem. We could return to the Moon or travel to Mars simply by using what we have al- ready designed. That said, there is a worry- ing unknown that prevents us from doing so airily, and we are not referring to the availability of adequate funding that we take for granted here. We refer instead to our incomplete knowledge of the effects that space radiation can have on the bod- ies of astronauts engaged for weeks, months or even years in interplanetary space or on the lunar or Martian surfaces. Although almost sixty years have passed since the launch of the first man into orbit, and in spite of significant research into the possible pathologies attributable to space radiation, our understanding of the risks space entails for astronauts who remain there for a long time is still very limited and a matter of discussion. In particular, there are significant disparities between basic research results and observed empiri- cal effects seen in astronauts exposed to non-negligible periods of space radiation. This is mainly due to various factors that limit the simulations in terrestrial environ- ments compared to the complex and rap- idly changing space weather, as well as the limited extrapolation of studies to human beings based on models developed for an- imals. For several reasons, these animal models do not faithfully represent the ac- tual human space radiation operating en- vironment, and they even less (or not at all) represent the complexity of human physi- ology. Specifically, models developed for a variety of animal species with different sensitivities and radiation responses may not be representative of human responses to exposures of equal intensity. Moreover, experimental models are based on histori- cal epidemiological studies that include ex- treme cases of radiation exposure, such as S pace radiation consists of not only photons, but protons and many of the elements of the periodic table. They enter the human body at energies that can approach the speed of light and can damage DNA. [NASA]