Terms like “cultural heritage” and “archaeology” might conjure Indiana Jones-lie scenes of old and ancient things buried under the sands of time. But even now, each one of us is producing material that could interest future humans trying to record and study our own era.
For those who believe that space exploration and astronauts’ first departures from Earth are culturally significant, then there is a wealth of objects that spacefarers—crewed and uncrewed, past and present—have left in the realms beyond our atmosphere.
“This stuff is an extension of our species’ migration, beginning in Africa and extending to the solar system,” says Justin Holcomb, an archaeologist with the Kansas Geological Survey. “I argue that a piece of a lander is the exact same thing as a piece of a stone tool in Africa.”
This idea is the heart of what Holcomb and his colleagues call “planetary geoarchaeology.” In a paper published in the journal Geoarchaeology on July 21, these “space archaeologists” detail how they want to study the interactions between the items we’ve left around the solar system and the hostile environments they now occupy. This research, the authors believe, will only become more important as human activity on the moon is set to blossom in the decades to come.
The idea of documenting and preserving what we leave behind in space isn’t a completely new concept. In the early 2000s, New Mexico State University anthropologist Beth O’Leary (who co-authored the paper with Holcomb) cataloged objects scattered around Tranquility Base, Apollo 11’s landing site on the moon. O’Leary later helped get some of those artifacts registered in California and New Mexico as culturally significant properties.
“I would argue that Tranquility Base could easily be considered the most important archaeological site that exists,” says Justin St. P. Walsh, an archaeologist at Chapman University in California who was not involved with the new paper. The base’s lunar soil can’t be declared a cultural heritage site because that would violate the 1967 Outer Space Treaty, which prevents any country from claiming the soil of the moon or another world. But scholars can still list objects found there as heritage.
Naturally, O’Leary’s catalog includes the remnants of Apollo 11’s lunar module and its famed US flag, along with empty food bags, utensils, hygiene equipment, and wires. What is space junk to some is precious culture to space archaeologists. Even long-festering astronaut poop has its value—“that’s human DNA,” Holcomb says.
Archaeological sites on Earth are deeply impacted by the processes of the world around them, both natural and artificial. Likewise, Tranquility Base doesn’t just sit in tranquility. The moon’s surface is constantly bombarded by cosmic rays and micrometeoroids; even faraway human landings can kick up regolith showers.
Holcomb and his colleagues want to study the various states objects are left in to learn how sites on the moon and other worlds change over time—and how to preserve them for our distant descendants. “We think in deep time scales,” says Holcomb. “We’re not thinking in just the next five years. We’re thinking in a thousand years.”
That sort of research, the authors say, is still quite new. Holcomb, for instance, wants to study what happens to NASA’s Spirit rover on Mars as a sand dune washes over it. Other planetary geoarchaeology projects might focus on what the moon’s environment has wrought upon artificial materials we’ve left on the lunar surface.
“We can find out more about what happened to [castoffs] in the length of time they’ve been there,” says Alice Gorman, an archaeologist at Flinders University in Adelaide, Australia, who also wasn’t a co-author.
On Earth, Gorman and colleagues plan to replicate Apollo astronauts’ boot prints in simulated lunar soil and subject them to forces like rocket exhaust. Gorman believes even engineers with no interest in archaeology may want to take interest in work like this. “These same processes will be happening to any new habitats built on the surface,” she says. “With the archaeological sites, we get a bit of a longer-term perspective.”
The moon is the immediate focus for both this paper’s authors and other space archaeologists, and it’s easy to see why. After several decades of occasional uncrewed missions and flybys, NASA’s Artemis program promises to spearhead a mass return to the satellite’s surface. The Artemis program is slated to land on the moon’s south pole, far away from existing Apollo landing sites. But a flurry of private companies have emerged with the goal of not just touching the moon as Apollo did, but extracting its resources.
Space archaeologists fear that all this future activity will place past sites at risk. “We barely know how to operate on the moon,” says Walsh.
There are some indications that the broader space community is thinking about the problem. The Artemis Accords (a US-initiated document that aims to outline the ethical guidelines for the Artemis era) and the Vancouver Recommendations on Space Mining (a 2020 white paper by primarily Canadian academics that proposes a framework for sustainable space mining) express a desire to protect space heritage sites.
Of course, these are only words on nonbinding paper, and space archaeologists do not think they go far enough. Holcomb and colleagues want experts in their field to be involved in planning—for instance, steering scientific and commercial space missions away from spots where they might interfere with existing cultural heritage. There is earthbound precedent for such a role: In many countries, archaeologists already assist infrastructure projects.
“We know we’re going to go there someday, so let’s make sure that we have the protections in place before we go and ruin things,” says Walsh.
Moves like this can’t protect lunar heritage from every possible harm: A future satellite could very well crash-land on Tranquility Base and wreck the last remnants of Apollo 11 there. But space archaeologists say that it is valuable to take any steps we can.
“I think the paper is a really fantastic demonstration of how any mission to the moon has to be about more than just engineering, and it has to be interdisciplinary,” Gorman notes. “It’s very timely that it’s been published now, while there’s still time to incorporate its recommendations into actual lunar missions.”