In a few years, the International Space Station will be the final lost civilization.

Sometime after 2030, a SpaceX spacecraft will drag the ISS into Earth’s atmosphere, where heat and friction will tear it apart. A space station the size of a football field, where astronauts from 22 countries have lived and worked for about 30 years (when this is all over), will be effectively erased from existence.

Much of human culture is shaped by the things we make and use, and how we interact with our environment. And once the ISS burns up in the upper atmosphere, the physical evidence of its space culture will simply be gone.

Archaeologists led by Alice Gorman of Flinders University and Justin Walsh of Chapman University are trying to explore the soon-to-be-lost culture of the ISS and its crews before it’s lost. In a recent study, Gorman, Walsh and their colleagues asked astronauts to take regular photographs of six square sections of walls and surfaces aboard the ISS. This provided clues about how people on the station used their space and adapted to the strange environment of an orbiting space station. The result is both a record of a place and culture that will soon disappear, and a valuable source of data to help engineers design future space stations.

The researchers published their work in the journal PLOS ONE.

The ISS is in an unusual location and has a tiny population. Fewer than 300 people have visited the station so far, with trips lasting from a few days to over a year. But life on board the ISS has its own traditions, its own etiquette, and its own idiosyncrasies and habits. According to Walsh and his colleagues, the station is a micro-society with its own culture.

In this image, astronaut Kayla Barron uses tape to mark the corners of a square on one of the station’s walls. For 60 days in early 2022, astronauts aboard the ISS regularly took photos of six squares like this one on walls and surfaces around the station. Walsh and his colleagues used the photos to track what items people used and stored in different locations. This, in turn, provided clues about how people lived and worked in different parts of the station.

Here on Earth, the story of who lived and what did in a place is encoded in layers of objects left behind and buried beneath layers of soil. Archaeologists call this “material culture”: the physical things that people left behind. Archaeologists obtain this evidence by digging in the ground, but also by using satellite or aerial photography to look for structures that have been buried or obscured by plant growth. On the ISS, archaeologists can use photographs to learn about the station’s material culture.

For Walsh and his colleagues, each square on board the ISS is like a “test pit,” a small hole that archaeologists dig to take samples of the soil layers and artifacts at a site on Earth. And each day’s photo is like a new layer of soil and artifacts, showing what people have done at that place over time.

While archaeologists on Earth look for stone tools, charred remains of cooking stoves, or radar traces of ancient canals and fortifications, space archaeologists could look for other things that provide clues about human habits: hygiene items stuck to any wall near the toilet, for example. They could also examine objects like plastic clips or Velcro used to hold things in place (a category of things Walsh and his colleagues call “gravitational proxies”).

It turns out that over the years, crews started using some empty spaces for convenient storage – such as a wall between the exercise equipment and the restroom. The wall had no official purpose, but crews started using it to store their toiletries and hygiene items, probably just because the location was convenient thanks to its proximity to the restroom.

“If you look at older historical photos of this place, you don’t see the same things there as when we looked at it. I think in the virtual model of the ISS on Google Street View, there is actually a toolbox attached to the wall. When we looked at it, it was not visible at all,” says Walsh. “So this area can be changeable in its function depending on what the astronauts who are currently part of the crew want to do with it.”

That’s the kind of detail that Walsh says we still need to uncover through archaeology, because it’s often not mentioned in official station plans and even astronaut biographies – if only because it’s the kind of detail that people rarely think about. And it could be important in planning future space stations.

“One of the themes that emerged during our project is the need for more crew autonomy: to have some sense of control over the context, for example how to decorate it or where to do certain activities,” says Walsh.

Another “test shaft” revealed that the area originally intended to be a maintenance area was actually a storage room. Walsh and his colleagues found no signs of actual work there, but instead found a lot of stored equipment.

“There were a lot of objects, but as it turned out, those objects weren’t moving much,” says Walsh. “They basically remained static, and that led to the interpretation that it was a storage area.”

Such information is not only useful for understanding culture on space stations, but also helps in designing future stations that are more consistent with people’s actual activities and their actual use of space in orbit.

“During the debriefing, one crew member said he liked the idea that systematically studying these sites over a longer period of time could lead to better space stations,” says Walsh. “They understood that observing the material culture of the space station could lead to insights that would not otherwise have been available to people.”

The ISS Archaeology Project Team is still working through data from the other four “test pit” squares, which are located on experiment racks in the Japanese Experiment Module and the European Laboratory Module, a wall near the kitchen table, and a workstation in the U.S. Laboratory Module.

“The galley is probably what people want to know most,” says Walsh.

A previous study focused on where the station’s crew actually spends their time on board, based on where they appear in thousands of photographs taken over the past 24 years. The International Space Station is supposed to be just that – international – but each module belongs to a specific country’s space agency. And it turns out that crew members spend most of their time in their own country’s modules.

This is especially true for Russian cosmonauts, who stayed almost exclusively in the Russian modules – crew members from other countries, on the other hand, were very rarely seen.

The latest study found the same thing. The maintenance area, which the astronauts converted into a storage room, is located in an area that connects the U.S., European and Japanese modules. And as expected, Walsh and his colleagues discovered only a single Russian artifact, a pack of sanitary wipes tucked into a hygiene kit. That’s the kind of physical evidence that tells archaeologists who uses a room – and who doesn’t.

In 2021, Walsh and his colleagues used some photographs of crew members to study how the crew decorated the walls of their station modules. In the Russian module, however, the cosmonauts decorated the walls with religious icons, paintings of Russian politicians, and, most importantly, photos of cosmonaut Yuri Gagarin, the first man in space.

A framed photo of Yuri Gagarin also hung on the rear wall of the Russian Zvezda module. And even older photos from the Mir space station and the Salyut-7 space station show that Gagarin’s photo has been part of the station decoration for Russian cosmonauts for decades. For the current ISS crew, it is a way to show their connection to a much older space culture.

In the U.S., European and American modules, crews decorate public areas with mission badges, nameplates and photos of former crew members (and a geocaching tag). Walsh says this connects ISS crews not only to older generations of space explorers, but also to the very first humans who painted and drew cave walls tens of thousands of years ago.

“It’s like the refrigerator door with your children’s drawings or vacation photos that you hang on it. It’s a way for us to make statements about who we are and also to underline important elements of our identity,” says Walsh. “That’s what I mean by ‘people in space are people.’ People will be people.”