Xenoarcheology: the search for extraterrestrial death

Thanks for tuning back into the BeX Files! Get out your trowels and sieves, because this Friday, we're excavating extraterrestrials. 

Few motifs in alien lore are more entrancing than xenoarcheology, the study of unearthing un-Earthlings. This trope has been on my mind lately as I’m replaying Outer Wilds, a clever game released in 2019 that has ripped my heart out on several occasions—in a good way!

The story follows an alien who explores their solar system looking for clues about its previous inhabitants, an advanced civilization that went extinct long before the rise of the character’s species. 

I love this game for so many reasons, from the interplanetary puzzles, to the rustic campfire aesthetic, to the bold ending. I was fortunate to speak to the game’s creators for Motherboard’s Space Show (2020-2021, RIP); here’s that episode, which does not include major spoilers. 

Outer Wilds is, of course, far from the only story premised on the idea that our search for extraterrestrial life might end with the discovery of extraterrestrial death. Indeed, it is a common touchstone even just within gaming, surfacing in blockbuster franchises like Mass Effect and Halo. 

Off the top of my head, the exploration of alien ruins also shows up in Star Trek (countless times), The Expanse, the Alien franchise, multiple Arthur C. Clarke classics, and The Final Architecture series by Adrian Tchaikovsky. Wikipedia, ever the helpful servant on matters of rabbithole'd minutiae, has a helpful list of xenoarcheological tales.

The notion of excavating alien remains also animates a lot of popular lore, such as the whole “Ancient Aliens” mythos, or rumors of alien bodies in crashed saucers or buried in makeshift tombs. In recent years, the wild speculation that interstellar objects are alien artifacts also plays into a vision of a universe awash in the material flotsam of the dead.

There is clearly something resonant about these tales of bygone aliens, and especially the silent ruins of once-thriving civilizations. For starters, it appeals to everyone’s inner archaeologist, that childlike hope that we might find something revelatory in the dirt beneath our feet. Xenoarcheology blows this deep-rooted desire out to cosmic proportions.

Dead aliens are also, by definition, a lot less threatening than living ones. Encountering ruins and bodies allows human characters more time and space to ponder the ramifications of discovery, and to process what off-Earth extinction might mean for our own human future. To that end, a lot of xenoarcheological lore leans toward the cautionary tale; we wander in the valley of the alien dead to, ideally, avoid ending up in the same destination.  

But while searching for alien remains is a well-worn pastime in fiction, it is also one of the most promising efforts in the scientific search for life (just not-currently-alive life) elsewhere in the universe. In September, NASA announced that its Perseverance rover had discovered a potential biosignature on Mars. Here’s my 404 Media story on this tantalizing study, and I have another in the works with more context, so stay tuned. 

The redox reactions that Perseverance found at Jezero Crater, which was once home to a vast lake, may have either a geological or biological origin. Perseverance is not equipped with the tools to discern the source. The rover’s job is to find exciting samples and cache them so that a future mission can pick them up and bring them back to Earth for further analysis, as part of the international Mars Sample Return (MSR) program. However, a combination of internal mismanagement and Trump’s devastating cuts to NASA could result in the cancellation of the mission, potentially leaving these samples—and any microbial fossils therein—out of our reach.

With all that drama aside, I cannot help but wonder if humanity has already touched alien death through Perseverance, or maybe even previous missions (I wrote this WIRED piece last year that touches on past inconclusive results on Mars). This is not so much the work of a xenoarcheologist as it is of a xenopaleomicrobiologist, a job that would look great on a business card. I have no clue whether we’ll discover alien life in our own lifetimes, but Perseverance’s samples—locked in tubes within the rover’s belly—seem like the most likely near-term culmination of that goal.

What would it mean if our first encounter with aliens were with the fossilized remains of lake-dwelling Martian microbes from an unimaginably distant past? Some might find this outcome anticlimactic, given the expectations set by pop culture. At least one person, the philosopher Nick Bostrom, thinks it would “be by far the worst news ever printed on a newspaper cover” (here’s the context for that quote). 

But to me, there’s something compelling about finding hints of a tiny transient ecosystem that flourished while it could, and then etched its signature into a planet so it could be read by some apes billions of years later. It’s not as grand a vision as finding the archetypical alien ruins—buried reactors or collapsed cities made by an advanced extinct civilization—but it would prove that life on Earth is no fluke. The threshold to life, even in its most simple forms, would be lowered. Though it’s not the epiphanic moment science fiction has primed us for, it would still be the most profound discovery our species has ever made.  

So let’s bring the dang rocks back to Earth! 

Before closing this week’s file, I wanted to share a fun interview about my book FIRST CONTACT with Jim Harold of the Paranormal Podcast. We chatted about UAP, interdimensional aliens, trickers, and the GOAT: Rod Serling. 

That’s all for this week! Good luck with your xenoarcheological digs, everyone. Pro tip: Don’t touch any buttons on the artifacts you find. See you at the cosmic rest stop next Friday.