Exoarchaeology: What can space trash tell us about life, planets, and the cosmos?
Although I am a planetary scientist by trade, I also minored in archaeology while a undergraduate student at the University of California, San Diego. I also attended a Cyber-archaeological field school in Delphi, Greece during the summer before my final year. I have always sought to somehow combine my interest in the ancient civilizations with my interest in planetary exploration. My latest attempt to combine them is exoarchaeology, the study of artifacts in outer space, including on other planets.
The term exoarchaeology is a parallel to the older term exobiology, which was coined by Joshua Lederberg in 1960 to refer to the search for and scientific speculations about life beyond Earth. As discussed in the book, The Living Universe, by Steven Dick and James Strick, exobiology has since been expanded into the broader field astrobiology.
Astrobiology seeks to put life into a cosmic context. It draws on planetary science, astronomy, geology, biology among other fields. It seeks to investigate how life forms and evolves, whether life formed beyond Earth, and the future of life on Earth and beyond.
Similarly, exoarchaeology, currently concerned primarily with space heritage like the Apollo 11 landing site, could be expanded to consider culture and civilization in a cosmic context. This could be called astroarchaeology. Astroarchaeology would involve using physical and symbolic artifacts to investigate how culture and civilizations form and evolve, whether there are civilizations and culture beyond Earth, and the future of civilization and culture on Earth and beyond.
Culture and civilization are very important in archaeology. I will focus on culture. There seem to be as many definitions of culture as there are anthropologists studying the concept. For the purposes of this article though, I will define culture as the ability to make and use tools (material and symbolic) to adapt to and transform an environment. Although culture is a phenomenon of life, life that has culture has special properties.
Life is interesting. The astrophysicist Adam Frank in his popular book The Little Book of Aliens, points out that life differs from other matter in its complexity and tendency to follow trajectories that are hard to predict. If a star forms, it is relatively easy to predict what the star will look like in a few billion years. We just need to know physical properties like its mass and its temperature. The trajectory of life, on the other hand, is much harder to predict. How would we predict the emergence of the kangaroo or the anteater just based on the initial conditions of the formation of the solar system?
Culture takes this potential and unpredictability even farther. Culture (i.e., technology) may also be the only form of life that not only can spread across a planet but go interplanetary, and perhaps beyond.
Earth scientists generally agree that biological life has played an active role in shaping the state of Earth’s surface, oceans, and atmosphere. For instance, microbes mediate planetary cycles, such as the carbon cycle or the nitrogen cycle, to create an interconnected system. This interconnected system is part of what keeps Earth habitable. This may be true for other habitable worlds as well, such as Europa.
The idea that the earth system maintains its own habitability was first proposed in western science by planetary scientist James Lovelock and microbiologist Lynn Margulis as the controversial Gaia hypothesis. Earth’s biosphere may be self-perpetuating and self regulating like a planet-wide organism…creepy I know.
While biological life certainly transforms its environment, non-technological life may only be able go so far because it is limited within the range of conditions which allow for life to exist on a planet’s surface or interior. In other words, Biological Life may exist on billions of planets in the galaxy, but if most of this life dies once it leaves the planet’s atmosphere, a given biosphere can only ever be planetwide and not truly multi-planetary.
Cultural or technological life, on the other hand, has an unparalleled ability compared to other forms of life to transcend the bounds of its environmental limitations. Just think of the International Space Station. Low Earth orbit is completely beyond the required conditions for biological life to form let alone survive and thrive. Nonetheless, through science and technology, humans have found a way to live in outer space for long periods of time and may even live on other planets some day.
Technology could enable life to create an interconnected living system that is truly multiplanetary. The same way that life mediates planetary cycles on Earth, a future multi-planet civilization may regulate solar system-wide cycles, such as evolution of planetary orbits to prevent inhabited planets from getting consumed by the sun as it expands. The interconnected planetary system that is Earth’s biosphere is sometimes called Gaia. Perhaps, this solar system-wide technological system, or civilization, could be called Solaria.
If the technological life can go multiplanetary, could it go galactic or even intergalactic? Could Solaria become Galaxia as civilization spreads from star to star? Currently, there is no evidence that such multi-planetary technological systems, or civilizations, exist or could exist, but astroarchaeology could provide the tools to investigate that possibility.
The search for artificial structures within and beyond the solar system could tell us if technological life has in fact been able to move beyond the narrow conditions that allow life to exist on planetary surfaces. This search could be done using the traditional tools of planetary science and astrophysics, including telescopic observations and analysis of data from interplanetary missions across the solar system.
Such a search could reveal the extant to which technology enables life to shape cosmic evolution. Does it just shape it on only the planetary scale or also the solar system scale? Or does life shape the history of the universe all the way up to the cosmic scale? Space trash could help us investigate this question.
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