Archaeologists are working to understand how astronauts really use their space on the ISS—and help improve space habitats of the future.

Russian spacewalkers explore the spherical Prichal docking module, which is attached to the Nauka multipurpose laboratory module of the International Space Station. Image credit: NASA Johnson, Flickr

Soon after photos started arriving from the International Space Station (ISS), Justin Walsh spotted something unexpected: frosting. Tucked into a plastic bag hanging off the station wall, near a can opener and bottle of ketchup, were telltale red, yellow, and green tubes. Walsh was mystified. “What does frosting imply? Baking,” he said recently over Zoom. But baking in space is pretty much impossible. 

He got his resolution when astronaut Kayla Barron posted on Instagram that she’d made a birthday cake for a colleague. “They did it by cutting the tops off of muffins and gluing them together with honey, then covering the whole thing with icing and frosting,” Walsh says. To Walsh, an art historian and archaeologist at Chapman University, the frosting was physical proof of something less concrete: astronauts’ bond with one another. Cooking and eating “is not only about sustenance; it's about social relations,” he says—even 250 miles above Earth. 

He, fellow space archaeologist Alice Gorman, and their colleagues received the frosting photo as part of the Sampling Quadrangle Assemblages Research Experiment, known as SQuARE. The ISS, which is administered by multiple space agencies, is essentially a network of modules for cooking, sleeping, science research, and other uses that’s slightly larger than a six-bedroom house. Between January and March, astronauts on board took daily photos of six carefully chosen sites around their temporary home first at the same time each day, then at random times. The project was an interstellar version of the archaeological technique known as quick testing, in which archaeologists divide a new site into a grid of one-meter squares and dig “test pits” that provide a basic sense of what they might find. 

In SQuARE, those “pits” are one-square-meter areas marked off with tape, scattered across the American, European, and Japanese modules of the ISS in areas used for work, science experiments, cooking, and hygiene. The team will analyze the resulting photos in hopes of understanding how each area is used over time and, from there, identify opportunities to improve space habitat design. 

NOVA talked with Walsh about the challenges of space archaeology and why astronauts eat so many tortillas. 

Alissa Greenberg: Usually, archaeologists excavate sites because it’s the only way to learn about life in those places—all the people are long dead. But we can talk to these astronauts. Why not do that?

Justin Walsh: It's true that, for the most part, archaeologists do study the distant past. Contemporary archaeology developed starting in the 1970s. The first example of it was a project called the Tucson Garbage Project by a guy named William Rathje at the University of Arizona. He got the City of Tucson sanitation department to drop off samples of neighborhood garbage on a regular basis, and he and his graduate students went through it to understand the patterns of usage of different items.

What's really fascinating about it is that they then went and interviewed people from the neighborhood about their consumption habits. So first of all, he found that people were throwing out lots of meat that they weren't using. So he was able to show that people were being wasteful with this particular commodity. But then he went to talk to people about these things, and he found out some interesting facts. Such as when you ask people questions, the way sociologists and anthropologists often do, they are not necessarily really good at articulating the realities of their lives—or they don't want to. Which is also perfectly fair and understandable! I would not blame them for that. But what it shows is that what archaeology can do is provide additional insights into human practices and that those insights don't have to be about the distant past.

So, you can say, “Well why don't you just talk to the crew and ask?” or “Doesn't NASA document all that stuff?” Okay, we can absolutely do that, but that doesn't always work well—especially for astronauts, who are 100% good at staying on message and will not say anything to jeopardize their next flight to space. And as for the space agency, they don't do any forensic work on what's happened on the space station before. They're in the present and the future—and the past is gone. They're not thinking about what they can learn.

One of the SQuARE sample locations, in a U.S. module galley area, marked by yellow tape at each corner. On the wall, mesh bags hold ketchup, Sriracha sauce, chocolate, and other food items. In the upper right corner are plastic bags holding tubes of frosting, which indicated that a kind of “space cooking” activity was happening in this location. Image courtesy of Justin Walsh

AG: Why do you find space culture so compelling?

JW: Because humans are doing things there in an environment that we are 100% not adapted for. We literally cannot survive. So, we have to come up with all these technologies that allow us to survive in that environment, living in microgravity. And on top of that, there's the other issues of confinement and isolation: the bad food, the distance from family and friends. How do they work together and live together? 

One of the phrases that I like is that a crewed spacecraft is “a microsociety in a miniworld.” You have the transmission of culture and traditions—"this is how we do things, this is how this is laid out”— being handed down almost from generation to generation. For example, on the ISS they have dinner together every Friday. Most of the time it's in the Russian service module; sometimes it's in the American service module. Or on ISS their food is carefully designed, and there are different kinds of traditions associated. Things like there's no bread, because crumbs are bad in space. If you inhale a crumb, that could really be a problem, so instead they use tortillas for everything. Tortillas don't make crumbs.

AG: Can you talk about this most recent study? What’s the goal here?

JW: We've been doing this study of historic photos that document life on the space station over 21 years. We've got this body of photographs, both published photographs from Flickr and also unpublished photographs that NASA has now given us—thousands and thousands of photographs. We've been working for the last three years to develop machine learning techniques that would allow the automated tagging of people, places, and objects in the photos. But they were taken essentially randomly. They weren't taken at precise intervals. How do we even characterize what the potential problems might be with that? One way is by doing an actually systematic survey of the material culture of the space station over the short term. That's what SQuARE is.

A NASA astronaut, a JAXA astronaut, and a Hungarian-American space tourist pose in the Russian service module Zvezda in 2008. The wall behind them is decorated with items including flags, mission patches, portraits of Soviet space heroes, and Russian Orthodox religious objects such as painted icons. Image courtesy of Justin Walsh

In archaeology, we take soil that’s all the same type, same color, same consistency, and different from what's above it and what's below it or what's adjacent to it, as a group that reflects a particular period of time. We take all of those items as relating to one another, and therefore they are separate from and need to be interpreted differently from what’s above or below. So we're treating each photo that way, because it is a slice of time, separate from the next day or the previous day.

The fact that we're doing this one picture a day for each of six squares for 60 days, 360 images that were taken systematically at precisely defined locations, will allow us to better understand what the historic photos are all about. And likewise, what's happening in the historic photos—because there's so many of them and such a variety of things going on in them—will help us to interpret what we're seeing in the systematically recorded images.

AG: What have you found so far?

JW: We thought that the two experimental areas that we selected probably were not going to show very much change over time because they're basically just racks with scientific equipment. In fact, we were asked, “Are you sure you want to use those areas? Don’t you want to see where more activity is happening?” We had to say no because archaeology is not a treasure hunt. We want to actually see the full range. How would we be able to tell the difference between low activity and high activity if we’re only looking at high-activity areas?

It turns out that one of those areas is seeing hardly any change. But in one of the other areas, we actually have seen a lot of things moving around. Things are being stored there, like laptops and a video camera. It seems to be kind of a staging area for what's happening next door, a veggie experiment. So that's really interesting, because that shows that when things aren't happening in the location, it can be repurposed.

Another thing we’ve been seeing in the eating area is books. In one case there's been an actual physical book on the wall, just kind of stuck there for the time being—somebody put it down. But we've also seen an iPad with an e-book that was on. So, in a leisure moment, when you're eating by yourself, maybe you read a book or a magazine.

The way it works right now is that there's this kind of plate hooked to an adjustable arm. And the plate has some Velcro on the front of it, so that the back of the iPad that has Velcro on it can be stuck to it. And that's fine, maybe that's a good enough solution. But now we have evidence of a different way in which the space is being used. And in future space habitat designs you might want to accommodate it in order to make a better experience. If nobody had evidence that this is how this is being done, we wouldn't even be able to think of solutions.

In an image of a SQuARE sample in a U.S. hygiene area, NASA astronauts Mark Vande Hei and Kayla Barron take a self-portrait in the mirror. Image courtesy of Justin Walsh

Another aspect of the photo study—we placed a preprint of this on SocArXiv—is we had all these images from Flickr, 8,000 of them, and helpfully NASA has captioned all of them. We were able to scrape them and peel out particular words: the names of the crew members and the locations. Just with those two pieces of data from each item, for the first time it's possible to map out where men and women are across the International Space Station by module. 

And if we look at nationality by module, it does seem like there are some real results. In the Russian segment, unsurprisingly, Russians make up the majority of people. And unsurprisingly, in the U.S. segment Americans make up the majority of people who are in those modules. So this indicates that in what claims to be an international space station, there are national zones. That's not something anybody has ever been able to show data for. Again, anecdotally you might have expected that to be the case. But we're able to show the reality. And this is because of the way the ISS is managed. Those are official designations. Each agency decides what happens in its own module and what their own crew do. So as a result, you end up with inefficiencies.

AG: You’ve mentioned the future design of space habitats. Do you know if people doing that are watching your project? What kind of questions are they hoping you’ll answer?

JW: The ISS is maybe the most expensive building project humans have ever undertaken. A staggering amount of money for one piece of architecture, and $3 billion or $4 billion on NASA alone to maintain it each year. I think that we're looking to be able to give more accurate and more precise descriptions of the functions of different areas and how that relates to what the originally designed and planned functions of those spaces are. It's really important to be able to understand whether people are using spaces the way they're intended. If they're not, how are they being used?

We have at the moment four different commercial organizations that are planning, designing, building their own space stations, partly funded by NASA. And NASA and the other space agencies in ISS—except for the Russians—are currently already building a new space station that's going to go into orbit around the moon: Lunar Gateway. There are key problems that they're already focused on sorting out. But also, how do astronauts and designers create the conditions that mimic, or are as my colleague Alice says, are surrogates for, gravity? That is to say, handrails, bungee cords, Velcro, resealable bags. Where do we see Velcro building up over time? Those are areas where it might not have been foreseen, where it ended up that the crew realized that they were going to need more “gravity.” First of all, we have to identify those areas. And, second of all, then we have to understand why those areas are requiring “gravity,” because of the kinds of activities that are going on there. And then third, how do we anticipate that for future designs? 

Those kinds of questions, the space station companies really want to know that. Even when they have astronauts on their staff or in their executive boardroom, they still realize that there's a difference between anecdotes and data. So the really amazing thing about this is that, as (terrible pun) out of this world as this project is, it's the rare archaeological project that can actually have concrete and practical implications for the future.

This interview has been edited for length and clarity.

Correction: Due to a punctuation error, a previous version of this article indicated that the Russian space agency was building Lunar Gateway. It is actually a project of the four non-Russian ISS space agencies.

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