FTRL5 equipment for the Eneide Mission. This experiment is aimed at assessing the effects of the space environment (weightlessness and radiation) on rat thyroid cells. This experiment should provide further indications that may help in understanding why the sensitivity of the cells to radiation damage is related to their cell cycle and to the kinetics of the radiation. Furthermore it will help improve our knowledge of the effect of the space environment on the human body, especially with longer-term missions planned in the future (e.g. Mars).