Scientists continue to prepare for long trips to outer space, and therefore, it is their responsibility now to assess all the possible risks that travelers may expect in their difficult journey. As researchers from the University of Wisconsin in Madison (USA) found out, the very first danger is the spacecraft itself, or rather, its environment. Microbiologists compared two cultures of mold fungi Aspergillus fumigatus – one grew on the ISS, the other in the laboratory of the educational institution. The results of the study showed that in fungi that developed in orbit, stress resistance is higher and their effect on experimental animals leads to death, but there is no significant difference between cultures not found. No changes in DNA were detected. fumigatus causes opportunistic infections that do not affect the body with a healthy immune system. But in space, it is weakening, and astronauts are becoming more susceptible to pathogens. As a result, this can cause the development of serious diseases, for example, aspergillosis. With long-term missions, for example, to Mars, the risk will increase, since the longer a person is in space, the more vulnerable he is. And therefore, when planning space expeditions, it is necessary to develop a methodology with more thorough processing of the harvested premises of the aircraft.