astronaut Alexander Gerst scrubbing the ISS interior

Cleaning Up in Space: How Astronauts Maintain a Germ-Free Environment

Last Updated: February 1, 2023

Especially in this post-COVID world, we constantly hear about the importance of cleanliness and sanitizing. We’ve seen how quickly a disease can spread, especially among people in tight quarters.

So, how do astronauts establish and maintain a clean, healthy environment? What do they do if someone gets sick? Let’s explore cleanliness and health in space.

Why is cleanliness important in space

Cleanliness helps reduce bacterial and other microbial growth which helps decrease the chances of becoming sick. Keeping a tidy, clean area not only helps reduce the chance something hidden could be growing something unexpected, but also helps our mental health feel less stressed and cluttered.

In space, it’s even more important. Astronauts physically can’t access an emergency room or quickly and easily order new supplies as they are in low Earth orbit 200 miles away by rocket. 

A dirty environment in space also creates numerous potential hazards for the equipment, not just humans as a build-up of gunk in technical systems can cause any number of issues. Whenever space agencies send a probe, rover, or other instrument into space, it is assembled in a clean room where everything is sanitized and workers wear special suits to ensure that no stray microbes or bacteria contaminate the instrument. 

This is done to ensure we don’t contaminate alien environments, potentially opening the possibility of them mutating with the help of radiation or other environmental factors. It also reduces the chance of creating issues down the line if we find microbes and would have to worry about whether or not it developed in the alien environment (meaning the first sign of life off of Earth) or if we brought it there.

But space stations are a bit different because humans live in them. Microbes and bacteria are in our skin, gut, and other parts of our bodies, many of which are not harmful and are even essential to staying healthy. We introduce microbes into these environments and we need them to survive. 

But maintaining cleanliness helps keep these microbes from becoming potentially dangerous. During the final days of the Russian space station Mir, the crew inspected its systems to understand the decay of the space station. They found foot-ball-sized blobs of water containing microbes, bacteria, dust, and more in various systems. 

Space agencies continually research how to make spaceflight healthier and safer and they took many of the lessons from the Mir systems into account with subsequent missions on the ISS.

The challenges of cleaning in space

While many of us may struggle with maintaining a clean environment in our homes and offices, being in space offers a plethora of other challenges very different from when we are on Earth.

First of all, the International Space Station, about the size of a six-bedroom house, are extremely tight for the astronauts living and working there, and all the equipment necessary to keep the station functioning and habitable. They also can’t run to the store for more supplies. They have to be extremely strategic about the chosen supplies to ensure that they don’t take up unnecessary and unavailable space, but they need to be able to survive even if something doesn’t go according to plan. 

One thing that is often considered essential for cleaning here on Earth and one we often take for granted is water. Water is heavy and just like with any other supply, space agencies need to be strict and efficient on how much weight is sent up in a rocket. But, like many other supplies, water is necessary for life, so astronauts conserve every drop they can, reducing waste. Water in space can cause problems though.

Moister environments welcome bacterial and microbial growth. In addition, water and electronics don’t mix and the space station is packed to the brim with electronics on almost every surface which help the station function properly. 

As we’ve talked about before in our article on how astronaut trains for zero-G environments, the lack of gravity creates a number of challenges for astronauts and equipment. Objects, including tiny particles, float on the ISS. They remain where they are unless they are pushed by an outside force, meaning they can hang around more so than here on Earth. But objects that are pushed in some way float very easily, which can cause water and cleaning supplies to float into parts of the space station. 

We’ve done studies on microbes in space to find that they have adapted just fine to life in space, some even do better than when on Earth. While they haven’t made massive leaps in evolution, they can certainly thrive in space. 

Cleaning in zero-G requires vigilance, concentration, and special tools to help ensure that surfaces and the very air remain clean without damaging anything.

Every Saturday morning, the astronauts living in the ISS will do some cleaning. In the above video, ESA astronaut Tim Peake shows us what it is like to perform cleaning duties in a weightless environmentIt’s quite the workout, isn’t it?

The tools and techniques used for cleaning in space

Since the early days of space travel, we’ve known the importance of keeping a clean environment and this focus has only increased, resulting in research to keep the space station and the people living on it as clean and healthy as possible. Different techniques and tools have been developed to ensure this.

First and foremost, there is a rigorous cleaning schedule on the ISS to ensure that they and all the equipment stay clean and healthy. Although they do have daily cleaning duties, especially in areas of high use and concern such as Node 3, where the toilet and the exercise equipment are located, and Node 1, where astronauts eat, Saturdays are designated as the big cleaning day since during the week they are often busy with other work duties.

Second, the station has systems to help maintain a clean environment. The ventilation system always has a breeze to help make sure particles such as dust and microbes don’t stick around in the air and are instead pushed to the vents which utilize HEPA filters and others to filter out any potential particles as much as possible. 

The water reclamation systems conserve and reuse as much water as possible (about 93% of the water it receives), even from sources like urine, utilizing a heated spinning distiller to remove the contaminants without the presence of gravity. Many systems such as the toilet utilize suction and fans to ensure that waste is effectively collected. Trash is routinely collected and stored in four trash bins, three for dry trash and one for wet, which is anything that could produce a smell. These are taken and replaced during re-supply trips from Earth, sending the trash down to Earth to be properly disposed of.

Thirdly, astronauts utilize a number of cleaning tools, many similar to here on Earth and some adapted. Part of the cleaning schedule every week is disinfecting surfaces utilizing different antimicrobial cleaners and wipes (including simple alcohol wipes). These antimicrobial solutions are continually being researched to ensure that they are as effective as possible including by outside companies such as a recent study by Boeing which focused on the effectiveness of an anti-microbial coating. 

In addition, the ESA recently performed a study on five surface materials to repel microbes. Astronauts also utilize vacuum cleaners with special attachments and filters to suck up any debris, particularly around the vents where it gathers thanks to the air systems.

The role of personal hygiene in maintaining a clean living environment

Maintaining personal hygiene helps ensure your body clears itself of any buildup of microbes, skin cells, yeast (a natural byproduct in our skin), and general grime built up over time. If these are left on our bodies, they will not only contaminate other objects, but clog up our natural systems, making it harder for our bodies to maintain homeostasis. 

Hand washing and sanitizing can help to ensure that we are also removing or killing any germs or microbes that can cause disease. Unfortunately, these kill indiscriminately, also ridding our skin of the beneficial microbes and oils that help our skin. Consistent, but moderate use is essential in addition to additional moisturization methods to protect our skin.

Since astronauts are the source of the microbes on the space station, they need to be extremely diligent in their personal hygiene. Their procedures and many of the materials are similar to what is used in hospitals for caregivers and patients. Showers and baths aren’t an option in zero-G as the water would float everywhere. Instead, they utilize shampoo and soap that don’t require water or rinsing including towels that contain the soap to reduce waste. They have to be very careful to ensure that the soap bubbles don’t wander off. They also utilize standard alcohol wipes to keep their hands and faces clean. Other personal hygiene materials such as razors, toothbrushes, and toothpaste are similar to or even the same as those on Earth, but again require more care in ensuring that nothing wanders off thanks to the lack of gravity.

In addition to standard hygiene protocols, space agencies utilize a number of procedures to help make sure that astronauts stay healthy during their time in space, reduce the chance of getting sick, and prevent the disease from spreading if someone does become sick. Spaceflight changes our bodies in ways we still don’t fully understand and it also affects how we become sick and how the illness might travel, again in ways we are still researching. 

In fact, many astronauts who usually have “a good immune system” here on Earth are more susceptible to colds and allergies in space. In particular, the lack of gravity is considered to be an important factor in this because the particles don’t fall and settle as they would on Earth, but stay suspended in areas where they can more easily transmit to others. HEPA filters and better air ventilation have helped with these concerns, but it is still an area of constant research.

Strict quarantines and medical procedures are implemented in the weeks leading up to going to space to ensure that the astronauts are healthy before going up. This was instituted after Apollo 7 in 1968 when Commander Wally Schirra likely came on board with a cold and subsequently passed it to the other crew members. Everyone was thankfully ok, but it created a very uncomfortable working situation, especially during re-entry. 

Additional medical checks (including blood, urine, and saliva tests) and even quarantines are implemented after they arrive on station to protect them and any astronauts who were already on station from getting sick. Astronauts have gotten upper respiratory infections or colds, urinary tract infections, and skin infections while in space over the years. Today, each astronaut undergoes regular telehealth sessions with a designated medical professional here on Earth to keep track of each astronaut’s health, adapting their procedures, diet, exercise, etc. as any potential concerns come up to reduce the chance of getting sick and to catch and treat issues as soon as possible. 

Recently, the first blood clot was found and treated in space. When astronauts get sick, they are quarantined to their sleeping quarters with medicine. They wear a mask to help contain it, and they have cultures taken and tested to provide the most effective treatment. 

All of the methods discussed have been designed for astronauts on a space station that is continuously operated by humans or a spacecraft of some kind. Research is currently being done on how factors, concerns, and solutions would change for future space explorers on the Moon or Mars.

Cross-contamination of our microbes to the new environment or from it to us is of vital concern in addition to the fact that the astronauts would be even further away from emergency medical help. Even the proposed Gateway station around the moon presents issues as there will likely be extended periods without habitation and therefore we need to prevent microbial growth while it is empty.


Cleanliness is an important aspect of keeping ourselves and our spaces functioning healthily. In space, the remoteness, lack of resources and space, and effects of a zero-G environment make cleanliness even more important and difficult. 

As was made blatantly obvious during the early spaceflight missions, maintaining cleanliness and health is vital to ensuring a successful, safe, and healthy mission for all involved. Research is continually being conducted to better understand how our bodies, technical systems, and the microbes that travel with us adapt to life in space and how to maintain a clean and healthy space for our current and future spacefarers.

Sarah H.

Sarah Hoffschwelle is a freelance writer who covers a combination of topics including astronomy, general science and STEM, self-development, art, and societal commentary. In the past, Sarah worked in educational nonprofits providing free-choice learning experiences for audiences ages 2-99. As a lifelong space nerd, she loves sharing the universe with others through her words. She currently writes on Medium at and authors self-help and children’s books.

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