Habitable Zones

The Interplanetary Habitable Zone

By Keith Cowing
Status Report
astro-ph.EP
February 17, 2026
Filed under , , , , ,
The Interplanetary Habitable Zone
Illustration of some of the multi-modal factors that may contribute to an IHZ in our solar system, overlaid on traditional habitable zones: the circumstellar habitable zone and the zone where closed icy ocean worlds can exist. — astro-ph.EP

The concept of a system-wide measure of the sustainment of life (habitability) for space-faring interplanetary species is introduced and explored.

Although largely agnostic to the details of how interplanetary life might operate (e.g., via technology or by utilizing organism traits that are, as of now, unknown to us), some assumptions must be made about energy harvesting, orbital mobility costs, radiation risks, and resource requirements.

A multi-modal figure of merit is developed for evaluating an interplanetary habitable zone (IHZ). An agent-based model is also developed to simulate the dispersal of interplanetary life in a planetary system and characterize the IHZ. For the solar system, resource weightings between planetary bodies dictate many overall behaviors, including the sequence of migration from Earth to the Moon, Mars, and asteroid belt.

Comparisons with the Trappist-1 exoplanetary system also point to critical sensitivities in the balance between resource availability and risk or cost factors (e.g., radiation risks and orbital Delta-v costs) that determine the structure of an IHZ.

Results suggest that our solar system may have an inherent, and significant, advantage for a space-faring species over a system like Trappist-1. This modeling approach may also have application to emerging space economies in our own solar system.

Caleb Scharf

Comments: 38 pages, 14 color figures, submitted to The Astrobiology Journal
Subjects: Earth and Planetary Astrophysics (astro-ph.EP); Popular Physics (physics.pop-ph)
Cite as: arXiv:2602.13404 [astro-ph.EP] (or arXiv:2602.13404v1 [astro-ph.EP] for this version)
https://doi.org/10.48550/arXiv.2602.13404
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Submission history
From: Caleb A. Scharf
[v1] Fri, 13 Feb 2026 19:13:00 UTC (4,421 KB)
https://arxiv.org/abs/2602.13404
Astrobiology

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) 🖖🏻