Terraforming & Geoengineering

An Agnostic Biosignature Based on Modeling Panspermia and Terraformation

By Keith Cowing
Status Report
March 22, 2024
Filed under , , , , ,
An Agnostic Biosignature Based on Modeling Panspermia and Terraformation
Target planet selection and terraformation. A. The objective function, used for determining the destination of life from a terraformed “parent” planet. Candidate destinations are first constrained by a maximum positional distance threshold; among these candidates, the planet closest in composition to the parent planet is chosen as the target. B. Simulations are initialized with 1 origin of life, causing the initial distribution of planet compositions (seen in A) to become correlated. C. An example of how we determine target planet composition when retaining 10% of the preterraformed planet composition. Note that while our simulations use a 3D space, the concept figure shows only show a 2D space for clarity. — astro-ph.EP

A fundamental goal of astrobiology is to detect life outside of Earth. This proves to be an exceptional challenge outside of our solar system, where strong assumptions must be made about how life would manifest and interact with its planet.

Such assumptions are required because of the lack of a consensus theory of living systems, or an understanding of the possible extent of planetary dynamics. Here we explore a model of life spreading between planetary systems via panspermia and terraformation. Our model shows that as life propagates across the galaxy, correlations emerge between planetary characteristics and location, and can function as a population-scale agnostic biosignature.

This biosignature is agnostic because it is independent of strong assumptions about any particular instantiation of life or planetary characteristic–by focusing on a specific hypothesis of what life may do, rather than what life may be. By clustering planets based on their observed characteristics, and examining the spatial extent of these clusters, we demonstrate (and evaluate) a way to prioritize specific planets for further observation–based on their potential for containing life.

We consider obstacles that must be overcome to practically implement our approach, including identifying specific ways in which better understanding astrophysical and planetary processes would improve our ability to detect life. Finally, we consider how this model leads us to think in novel ways about hierarchies of life and planetary scale replication.

Harrison B. Smith, Lana Sinapayen

Comments: 16 pages, 20 figures
Subjects: Earth and Planetary Astrophysics (astro-ph.EP); Instrumentation and Methods for Astrophysics (astro-ph.IM); Populations and Evolution (q-bio.PE); Quantitative Methods (q-bio.QM)
Cite as: arXiv:2403.14195 [astro-ph.EP] (or arXiv:2403.14195v1 [astro-ph.EP] for this version)
Submission history
From: Harrison Smith
[v1] Thu, 21 Mar 2024 07:42:07 UTC (1,394 KB)

Explorers Club Fellow, ex-NASA Space Station Payload manager/space biologist, Away Teams, Journalist, Lapsed climber, Synaesthete, Na’Vi-Jedi-Freman-Buddhist-mix, ASL, Devon Island and Everest Base Camp veteran, (he/him) 🖖🏻