Two NASA astronauts who were stranded on the International Space Station (ISS) for nine months were the subjects of a new study which revealed that excessive cleanliness on the spacecraft could have negative effects on astronauts’ health.

Normally, astronauts spend up to six months in the orbiting laboratories, but NASA’s Sunita Williams and Barry Wilmore stayed on the ISS for more than nine months, much longer than planned.

During long missions in space, astronauts can experience health problems such as immune system disorders, skin rashes, and inflammatory conditions. Determining the exact reasons behind these issues had been quite challenging. A new study suggests that these illnesses could be linked to the “extremely sterile structure” of the ISS.

While there are billions of microbial species on Earth, some are beneficial for human health while others can lead to diseases.

ASTRONAUTS CARRY MICROBES

Beneficial bacteria in the human body strengthen the immune system, prevent infections, and support gut health.

Researchers found that the microbial diversity on the ISS is significantly lower compared to Earth and most of the microbes are brought there by astronauts. The lack of bacteria on the space station may weaken astronauts’ immune systems, making them more susceptible to various skin diseases, cold sores, fungal infections, and shingles. By collaborating with astronauts, the team conducted the most comprehensive study of the ISS microbiome, collecting swab samples from 803 different surfaces on the station. Samples were brought back to Earth and analyzed to identify the bacterial species and chemicals present. Additionally, three-dimensional maps were created to understand how these microbes interact on surfaces. Studies revealed that the main source of microbes on the ISS is astronauts’ skin, and cleaning products and disinfectants are present on almost every surface. 

However, the diversity of microbes varies depending on the modules of the space station and these differences change based on the use of each module. For example, areas for eating and food preparation contain food-related microbes, while areas for cleaning contain more microorganisms associated with urine and feces.

LIKE A HOSPITAL  The ISS microbiome was found to have much lower diversity, similar to industrial and enclosed living spaces on Earth. This creates a situation resembling hospitals and isolated living areas. The team discovered that cleaning and disinfectant chemicals suppress microbial diversity and this situation could lead to health issues for astronauts. Researchers suggest increasing microbial diversity to reduce health problems for astronauts during space flights.