The Havera Hypothesis: Coupled Constraints on a Star-Independent Aerial Microbial Biosphere in Hydrogen-Rich Free-Floating Planets

The Havera Hypothesis is a preliminary theoretical astrobiology study investigating whether a free-floating planet with a sufficiently massive hydrogen-rich atmosphere could sustain a long-lived microbial biosphere entirely within its atmosphere, without stellar radiation or a habitable planetary surface. The study develops a coupled screening framework considering thermal habitability, liquid-water cloud formation, microbial atmospheric residence, chemical free-energy supply, phosphorus replenishment, and refractory nutrient transport. A sequence of exploratory models (HAVERA-0 through HAVERA-6) culminates in a 250,000-draw Monte Carlo parameter-space experiment. Under the assumptions and parameter ranges of the screening framework, a non-zero region satisfies all modeled constraints simultaneously. This result does not establish that Havera-class worlds exist or are habitable, and the Monte Carlo pass fraction should not be interpreted as an occurrence probability. The study identifies condensation-inhibited atmospheric transport, chemical disequilibrium, and long-term nutrient closure as major targets for higher-fidelity modeling. This is a preliminary, non-peer-reviewed theoretical study.