Researchers at University of California Irvine exposed mice to radiation similar to the cosmic rays that permeate space and found the animals experienced declines in cognition and changes in the structure and integrity of brain nerve cells and the synapses where nerve impulses are sent and received. The mice became easily confused and lost their tendency to explore new environments. Similar cognitive impairments are likely to be felt by astronauts traveling to Mars, according to the researchers. Even with shielding, the effects of cosmic rays exposure are sure to be noticed, considering the journey to Mars lasts six to eight months. This without counting the time spent on the red planet and the journey back home.