Interstellar Colonization With Slow von Neumann Probes

SÉBASTIEN LOISEL

2026.79.0390

DOI https://doi.org/10.59332/jbis-079-10-0390

Tipler [26] argued that self-replicating von Neumann probes traveling at 0.1c could colonize the entire Galaxy within ~108 years. However, reaching 0.1c remains far beyond demonstrated technology. We show that propulsion speed is not the binding constraint on interstellar colonization. A von Neumann probe traveling at 0.0005c using nuclear-electric ion propulsion can survive the resulting 10,000-year transit between neighbouring stars: stored cold, unpowered, and mechanically quiescent, the dominant degradation mechanisms, which are thermally activated (diffusion, creep, phase transformations), are suppressed by factors exceeding 10-19 at a storage temperature of 50 K, while the principal exception, cosmic ray damage, accumulates to doses that are negligible for metals and manageable for shielded semiconductors. The required technologies (cryogenic preservation, argon ion drives, fission reactors, long-lived radioisotope power) exist today or are within near-term reach. The design life is set not by thermal degradation but by cosmic ray dose and stochastic electronics failures, and carries margin for hops of up to ~10 light-years, comfortably above the ~6.3 light-year percolation threshold of the local stellar distribution. A branching-process analysis of probe attrition shows that colonization is robust to per-hop losses of tens of per cent, and that the colonization wavefront would cross the galactic disk in ~3 × 108 years. We briefly discuss the bearing of this result on Fermi’s question.

Keywords: Extraterrestrial Intelligence, Space Vehicles, Astrobiology