P2-ALTLIFE: Evidence Boundaries for Xeno-Nucleic Acids, Alternative Solvents, and Noncanonical Life Chemistry

Abstract

A non-operational evidence package for evaluating xeno-nucleic acids, alternative solvents, and elemental-substitution claims without converting laboratory feasibility into claims of autonomous or extraterrestrial life. It preserves the independent negative result for GFAJ-1 arsenate-DNA substitution, separates six evidence gates from synthesis through extraterrestrial detection, and freezes unsupported boron/sulfur and invented-protein illustrations as concept-question provenance only. Selected XNAs support bounded laboratory information functions under engineered conditions; quantitative performance remains assay-specific. The package contains no synthesis, culture, genetic-transfer, delivery, containment, implantation, or scale-up protocol. NASA and NIH are cited only as sources and do not imply affiliation, review, or endorsement.