Beyond Legibility: Intentional Deep-Time Biological Archiving, Sterile Body Selection, and the Anthropocentric Archive Assumption

This paper proposes five connected contributions to the question of intentional deep-time biological record-keeping by intelligent civilisations. First: the boom-bust cycle of habitable planets — not mere speculation but a rational basis derived from planetary geology — makes sterile proximate body archiving not merely possible but logically expected of any civilisation aware of that cycle. Second: in-situ fabrication of archive matrices on the target sterile body, using local materials, is logistically simpler than specimen transport and leaves tool signatures as secondary evidence independent of archive survival. Third: sterile bodies are not permanently sterile — icy body impacts can initiate habitability, burying archives under new geology — requiring redundant distributed archiving across multiple bodies at different instability risk profiles. Fourth: the prediction horizon problem — redistributed archives can only be located by an intelligence capable of modelling the complete collision history of the relevant body system across the deposit timescale, meaning only peers of the depositing civilisation can find their archives. Fifth and most fundamentally: current archive search strategies assume archives will be legible to human cognitive and instrumental frameworks. This anthropocentric legibility assumption is the major constraint that current technosignature searches have not examined. An archive from a non-human intelligence may take forms currently classified as unremarkable biology, geology, or chemistry — and would be systematically missed by any search that assumes an archive looks like an archive to us.