Where Should We Look For Ancient Civilizations in the Solar System?

The search for life in the Universe takes many paths. There’s SETI, or the Search for Extraterrestrial Intelligence, which is searching for signals from a distant ancient civilization. There’s the exploration of our own Solar System, on Mars, or underneath the subsurface oceans of Europa and Enceladus, to see if life can be anywhere there’s liquid water and a source of energy. And upcoming space telescopes like James Webb will attempt to directly image the atmospheres of distant extrasolar planets, to see if they contain the distinct chemical signatures of life.

But according to Jason Wright, an astronomer at the Center for Exoplanets and Habitable Worlds at Penn State University, we could consider searching for evidence of ancient civilizations right here on Earth, or across the Solar System. Don’t get excited, though, so far “there is zero evidence for prior indigenous species in the Solar System.”

Artist's impression of the terraforming of Mars, from its current state to a livable world. Credit: Daein Ballard
Artist’s impression of the terraforming of Mars, from its current state to a livable world. Credit: Daein Ballard
In a paper, recently submitted to the arXiv electronic preprint archive entitled Prior Indigenous Technological Species, Dr. Wright describes how we might go about searching for the technological artifacts left behind by ancient civilizations that have evolved in the Solar System. Perhaps on an ancient, cooler Venus, or on Mars in a time when it was wetter and had a thicker atmosphere. Those civilizations could have arisen millions or even billions of years ago, destroyed themselves or left the Solar System, and only ancient traces of their culture and technology would still be around.

If a civilization had reached a high level of technology, where did it go? Wright suggests a variety of catastrophes, like a swarm of comets, self destruction, or even a nearby supernova explosion that irradiated the whole Solar System with high energy gamma rays. Even without a specific event, a civilization might have simply just died out, or became permanently non-technological. Of course, these possibilities face our own human civilization. It’s hard to read the paper and not consider the fate of humanity. Will future aliens search for scraps to learn about us?

Where should we look? According to Wright, Earth is the obvious, most habitable place in the Solar System, and it’ll be the easiest to search. Humans have dramatically changed the landscape of Earth. Our open pit mines, for example, are a clear indication that an intelligent species dug out a specific mineral from the ground. These might be obvious for millions of years, but over the course of billions of years, plate tectonics will have recycled those regions, absorbing the evidence back into the ground. Radioactive isotopes from ancient nuclear reactors, or fossils of ancient beings will have about the same lifespan. Beyond a few hundred million years, the Earth itself would have completely obscured any evidence of a technological civilization.

Inhospitable surface of Venus. Credit: Magellan
Venus is inhospitable today, but it might not have always been the case. Billions of years in the past, when the Sun was cooler, it might have had a thinner atmosphere and milder temperatures. It’s worth searching. That said, it appears that Venus has gone through major geological resurfacing events, where the entire planet’s surface turned inside out. Venus could easily hide its secrets.

Scientists are accumulating more and more evidence that Mars was warmer and wetter in the past, with eras when liquid water could exist on the surface for long periods of time. And unlike Earth and Venus, it doesn’t have active plate tectonics. Landscapes on the surface have remained there for billions of years. Well, okay, they’ve been pounded by meteorites, but they’re still there.

What should we be looking for? One idea is technological structures: ancient mining facilities, factories, even cities. On Mars, these structures could get covered by dust or worn down by erosion, so it’s entirely possible our space-based observations could have missed them. Even structures on asteroids and the Moon get eroded by micrometeorites wearing them down. Over the course of millions years, an ancient factory would look very similar to a small rocky outcrop. The real evidence could be hidden underground, safely protected from the surface erosion. We need more rovers and orbiters with ground penetrating radar to see below the surface.

The Lunar Laser Ranging Experiment placed on the Moon by the Apollo 14 astronauts. Credit: NASA
The Lunar Laser Ranging Experiment placed on the Moon by the Apollo 14 astronauts. Credit: NASA
There could be free-floating objects in the Solar System, like ancient space stations. Of course, if they’ve been abandoned long ago, they wouldn’t be functional, and that same micrometeorite erosion would have worn them down over the vast timescales. Furthermore, their orbits might not be stable, and could eventually crash into another world, or get kicked out of the Solar System entirely. Space stations out in the Kuiper Belt would be subject to less erosion, and better preserved over vast timescales. We need better telescopes and deeper surveys to answer this question.

The bottom line is that Dr. Wright doesn’t conclude there’s any evidence for ancient civilizations in the Solar System so far. But the reality is that we’ve only just begun to look. NASA’s Mars Reconnaissance Orbiter, which contains the most powerful telescope to ever travel away from the Earth has only mapped a few percent of the Martian surface at its highest resolution. Astronomers have only mapped a tiny fraction of the asteroids and comets zipping around the Solar System. And we’ve only had single glimpses at places in the outer Solar System, like Uranus, Neptune and Pluto.

There’s so much more searching that needs to be done. But while we’re at it, we should keep an eye out for ancient civilizations. If we did find an old factory, space station, or even the dumping ground of a precursor species, it would be a boon to our knowledge.

And might just give us a warning; advanced knowledge of what the future holds for our own civilization.

Original Source: Prior Indigenous Technological Species

11 Replies to “Where Should We Look For Ancient Civilizations in the Solar System?”

  1. If we are looking for something that may have been left hundreds of millions of years ago, much of the Earth’s surface is not stable enough. Probably most of the earliest relics of mankind were closde to water, so may be hundreds of feet underwater by now.

    If it was something that has been left where it could be found, how about one of the Moon’s poles? Or, if meteors are a problem, on the point that is on average closest to Earth.

  2. If they were spacefaring, I would say stuff might have been left at the polar craters on the Moon or Mercury. The asteroid belt would also be a good place to look.

  3. Ancient beyond belief, like when Atlantis dried out and was renamed Mars? Lets just say there once was a highly evolved society living on water world Mars. Lets say they became interplanetary and journeyed to Earth where they founded research and sample gathering stations. After several million years of growth they observe the approach of a rogue planet being captured by Sol. It is determined the rogue will penetrate deep in system before settling into a 200 year orbit. The gravitational influences from the intruder’s passages will disrupt the orbit(s) of existing asteroid belts, comets and planets and generally wreck havoc all round. The best chances for survival are to stay and trust their luck? or flee to a habitable planet they’ve found and named Eden.

      1. Are there any reasons to consider that Uranus was formed out of the nebula our Solar System originated from ?

      2. I chose to use Uranus as a rogue planet because of it’s oddball perpendicular to the orbital plane axis.. and it’s retrograde spin. SOMETHING odd happened to Uranus early on. It could have been a rogue?

      3. The tilt of Uranus’ axis of rotation is a sign of a violent collision very early in our system’s history, as Terra experienced it too. The odds of a gas giant such as Uranus being captured as rogue and yet fit right into the plane of the ecliptic are very low.
        If I recall correctly, there were some papers published about the orbits of the gas giants possibly migrating and influencing other bodies

  4. Can’t speak for anyone else. But for me, I wouldn’t mind planting myself on Kate Hudson’s taco.

  5. start with Göbekli Tepe, work backward from there…
    or look at the buried civilizations beneath the Black Sea and work backward from there…
    Even the Mississippian people of the Americas are a place to start.
    Where did these people come from?

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