Astronauts' dirty laundry has been revealed: discover how clothing is handled in space (video).

Regularly changing clothes and washing them is a basic hygiene rule. However, there are situations where taking these simple steps is not so easy: for instance, in space, where laundry is far from being a straightforward task, as noted by IFLScience.

The main issue with dirty clothes in space is that water is an incredibly precious resource in this hostile environment. Researchers point out that the resource is so valuable that even urine on the International Space Station (ISS) is not considered waste: it is processed, purified, and reused. Consequently, the usual method of washing with large amounts of water and detergents simply does not work on the ISS.

How dirty clothes are "washed" on the ISS

Astronauts on the ISS have a limited wardrobe, which means they have to wear clothes that can be reused. However, predicting all scenarios can be tricky: for example, Sunita Williams and Butch Wilmore were supposed to spend only a week in space last June, but due to spacecraft malfunctions, they became stranded on the ISS. The astronauts brought enough clothing for eight days instead of eight months, so they really had to stretch their wardrobe for an extended period.

Some clothing items are reused for several days, weeks, or even months, depending on how dirty and smelly they become. When clothes get too dirty and uncomfortable, the crew replaces them — dirty clothes become waste, with much of it being incinerated.

It’s no secret that many waste items thrown from the ISS do not return to Earth. Instead, they burn up in the atmosphere along with a significant amount of other trash. Researchers note that some cargo capsules sent to the ISS are not designed to return to Earth: they burn up in the planet's atmosphere, allowing astronauts to fill them with waste, effectively killing two birds with one stone.

Alternatives to incineration on the ISS

Currently, astronauts have no choice but to burn their dirty clothes; however, several promising alternatives are under development. For instance, scientists are testing fabric that inhibits the growth of bacteria and fungi.

It’s worth mentioning that this method would effectively reduce odor and improve hygiene, but it is unlikely to help with stains.

The multinational company Procter & Gamble has explored a range of products in space with NASA to demonstrate potential cleaning agents: one of these was Tide Infinity, a liquid detergent free of fragrances and solvents. It was intended that the water used after such washing could be safely reused. Its formulation was tested on the ISS in 2021, and in 2023, a similar Martian mission called CHAPEA (Crew Health And Performance Exploration Analog) utilized it for laundry with lower energy and water consumption.

Two years ago, NASA also tested Tide To-Go Wipes and Tide To-Go Pen, which were used to remove stains from ketchup, coffee, olive oil, and punch in space. In other studies, scientists have also been working on creating a washing machine that could operate not only in low Earth orbit but possibly on the Moon or Mars.