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Mold in Space: The Hidden Danger Astronauts Face


Space is the Perfect Habitat for Mold

As human beings explore the possibilities of and colonization, it is important to consider the unique challenges that come with living in an environment outside of Earth's atmosphere. One of these challenges is the growth of mold in space stations. Mold is a type of fungus that thrives in moist environments, making space stations an ideal breeding ground for it.

There are several factors that contribute to the growth of mold in space stations. One of the biggest factors is humidity. In space, humidity is created by the themselves, as their bodies release moisture through perspiration and respiration. Additionally, water used for cleaning or cooking can also contribute to humidity levels. Since there is no natural ventilation in space, the humidity can build up and create the ideal conditions for mold growth.

Another factor that contributes to mold growth in space stations is the lack of . Without gravity, air currents do not circulate as they do on Earth, making it more difficult for moisture to evaporate and for air to move through the . This creates stagnant air and a lack of ventilation, which can contribute to the growth of mold.

What Dangers Does Mold Represent To Astronauts During Space Travel?

Mold growth in space stations and can pose several health risks to astronauts during space travel. Some of the dangers of mold include:

Respiratory Problems

Mold spores can cause respiratory problems such as allergies, asthma, and other respiratory diseases. Breathing in mold spores can irritate the lungs and cause inflammation, which can lead to coughing, wheezing, and shortness of breath.


Exposure to mold spores can also lead to infections, particularly for individuals with weakened immune systems. This is because mold can produce mycotoxins, which are toxic substances that can cause a range of health problems, including infections.

Allergic Reactions

Mold spores can also cause allergic reactions in some individuals. These reactions can range from mild symptoms such as sneezing and runny nose to more severe symptoms such as anaphylaxis, a life-threatening reaction that can cause difficulty breathing and loss of consciousness.

Structural Damage

Mold growth can also cause structural damage to the space station or spacecraft. Mold can grow on and in between surfaces, weakening them and potentially leading to structural failures.

Reduced Mission Effectiveness

Mold growth can also reduce mission effectiveness by causing crew members to become sick or by damaging critical equipment and systems.

Mold Mitigation

To address the problem of mold in space stations, NASA has implemented a number of measures. These include using that are resistant to mold growth, such as certain types of plastics and metals. They also employ air filters and ventilation systems that can help to remove spores and moisture from the air, and circulate it more effectively.

NASA also encourages astronauts to maintain a clean environment and to take steps to reduce humidity levels. This includes wiping down surfaces regularly, using dehumidifiers, and avoiding activities that create excess moisture, such as cooking with large amounts of water.

Despite these measures, mold remains a persistent problem in space stations. As we continue to explore the possibilities of space travel and colonization, it will be important to develop new technologies and strategies to mitigate the risks of mold growth and ensure the safety and well-being of astronauts.

Case Studies

Apollo Program Experience With Mold

The was a series of manned missions conducted by NASA between 1961 and 1975, with the goal of landing humans on the and returning them safely to Earth. While mold growth was not a significant problem during the Apollo missions, there were a few instances where mold was discovered in spacecraft and quarantine facilities.

During the Apollo 12 mission in 1969, mold was found on a camera lens that had been left outside the spacecraft. The mold was identified as a species of Aspergillus, which is commonly found in soil and organic materials. The camera was disinfected with a fungicide, and no further mold growth was reported.

Another instance of mold growth occurred during the quarantine period following the Apollo 14 mission in 1971. The astronauts had returned with samples, and they were kept in a sealed container for 14 days to prevent any potential contamination. During this time, mold growth was discovered on some of the containers holding the lunar samples. The mold was identified as a species of Penicillium, which is commonly found in soil and organic materials.

To prevent any potential contamination from the mold, the affected containers were disinfected with hydrogen peroxide and then kept in a sterile environment. No further mold growth was reported, and the lunar samples were eventually distributed for scientific study.

Overall, the Apollo program's experience with mold was relatively minor compared to the challenges faced by modern-day astronauts living in the .

Skylab Experience With Mold

Source: NASA

Skylab was the first space station, launched into orbit on May 14, 1973. It was occupied by three crews of astronauts, who spent a total of 171 days in space. One of the challenges the Skylab crew faced was the growth of mold within the space station.

Shortly after the first crew arrived at Skylab, they noticed that some of the surfaces inside the station were covered in a fuzzy white substance. They soon realized that this was mold, which was growing on the walls, floors, and equipment.

The mold growth was likely caused by high humidity levels within the space station. The Skylab crew had to use a lot of water for their daily activities, such as bathing, cooking, and cleaning, and this moisture was not being effectively removed from the air. In addition, the Skylab crew had to deal with a malfunctioning air conditioning unit, which made the humidity problem worse.

To address the mold problem, the Skylab crew had to take several measures. They used a vacuum cleaner with a HEPA filter to remove the mold from surfaces. They also had to change their clothes frequently and take extra precautions when handling food and water to prevent the spread of mold spores.

NASA also sent up special cleaning materials and chemicals to the Skylab crew to help them combat the mold growth. The crew used a fungicide called SPOROCIDE to clean the surfaces of the space station, and also used an anti-microbial spray to treat the air filters and ventilation system.

Despite these efforts, the mold growth continued to be a problem for the Skylab crew. It is estimated that up to 80% of the air in the space station was contaminated with mold spores at one point. However, the Skylab crew was able to successfully complete their mission, and the station was eventually de-orbited in 1979.

The experience with mold growth on Skylab highlighted the importance of maintaining a clean and safe environment for astronauts in space.

Space Shuttle Experience With Mold

The program was NASA's program that ran from 1981 to 2011. During the 30-year span of the program, there were several instances of mold growth in the space shuttles.

One of the most notable instances of mold growth occurred during the STS-61 mission in 1993. Astronauts discovered mold on the walls and floors of the space shuttle Endeavour's airlock. The mold was identified as a species of Aspergillus, which is commonly found in soil and organic materials. The crew used disinfectant wipes and a HEPA filter to remove the mold and prevent its spread to other areas of the space shuttle.

Another instance of mold growth occurred during the STS-72 mission in 1996. Mold was found on food containers in the galley, likely due to the high humidity levels in the space shuttle. The crew used disinfectant wipes and replaced the affected food containers to prevent any potential health risks.

In addition to these incidents, NASA also conducted studies on mold growth in the space shuttles. These studies found that high humidity levels, poor ventilation, and inadequate cleaning were some of the main factors contributing to mold growth.

To address the problem of mold growth, NASA developed several measures, including using materials that are resistant to mold growth, improving ventilation systems, and implementing a rigorous cleaning and maintenance schedule.

Despite these measures, mold growth remained a persistent problem in the space shuttles throughout the program's history.

International Space Station (ISS) Experience With Mold

Source: NASA

The is a habitable artificial satellite that orbits the Earth, and it has been continuously occupied by astronauts since November 2000. As with any confined and closed environment, mold growth is a potential issue in the ISS, and the crew has had to deal with this problem on multiple occasions.

The first reported incidence of mold growth in the ISS occurred in 2004, when a sample taken from a water dispenser revealed the presence of Aspergillus and Penicillium molds. The crew had to clean the dispenser and monitor the humidity levels in the area to prevent further growth.

Mold growing on an ISS panel where exercise clothing was placed to dry.
Source: NASA

In 2011, another mold problem arose when mold was discovered on a ventilation fan in the Japanese module of the ISS. The crew had to clean the fan with hydrogen peroxide and replace the air filter to prevent the mold from spreading.

In 2016, a more serious mold problem was discovered in the ISS. Astronauts found mold growth on a fabric surface inside an air duct, and laboratory tests revealed the presence of two species of mold, Aspergillus flavus and Aspergillus niger. These molds are known to cause respiratory problems, and the crew had to take immediate action to address the issue.

The crew used a combination of hydrogen peroxide and a fungicide called Dow Corning Sylgard 184 to clean the affected area. They also adjusted the air flow and humidity levels in the ISS to prevent further mold growth.

The experience with mold growth in the ISS highlights the ongoing challenges of maintaining a safe and habitable environment in space, and the need for continued and development of new technologies to address these challenges.



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