Fireball Cycle Volume 4: Unique Planetary Vessel — Preconditions of Earth's Life Origin and the Screening Paradigm for Interstellar Migration

This paper is the fourth volume of the Fireball Cycle theory series, serving as the foundational prequel to the complete 4.6‑billion‑year planetary epic. The preceding three volumes respectively addressed Phanerozoic mass extinctions, the unified formation of fossil fuels, and the Archean water‑fire co‑origin of life. This volume directly targets the most fundamental precondition of all evolution: the planet itself must be a complete water‑storage vessel — this is the absolute and unshakable foundation for the persistence of all things. For a long time, the field of astrobiology has held a deep‑seated one‑sided view, exalting liquid water in isolation as the source of life, while severing the irreversible causal hierarchy among the planetary body, water, atmosphere, surface combustion cycles, and stellar orbital temperature — a fundamental logical flaw. This paper integrates astronomical observations, geological‑hydrological records, and a theoretical framework of macroscopic quantitative evaporation control experiments, constructing a three‑tiered, indispensable complete creation‑judgment system: First tier: Vessel‑foundation constraints. The planet must constitute a complete and qualified water‑storage vessel, with suitable gravity, magnetic field, and orbital temperature within the stellar habitable zone; it must develop undulating topography for water storage; its total global water volume must exceed the saturated adsorption threshold of continental weathered rocks and soils; and it must have both water and land. Simultaneously, planetary size imposes a bidirectional rigid constraint: too small — gravity is too weak to retain the atmosphere and surface liquid water, and the small surface area lacks the physical space to store massive water; too large — the cubic growth of sphere volume drastically increases the water‑absorption capacity of the strata. Theoretically, for planets of the same composition, doubling the diameter increases water absorbed by the rock matrix by a factor of 8; with the same amount of surface water, the water depth decreases by another factor of 4, making thin surface water layers evaporate quickly, so stable surface free water cannot persist long‑term. Open surface liquid water bodies, through continuous evaporation, are the core source for replenishing planetary atmospheric components; once surface water completely dries up or the entire globe freezes at low temperature, without continuous liquid‑water vapor supply, the atmosphere will continue to be lost and dissipate. Solid ice lacks the dissolution and transport activity of liquid water, ultimately losing all functions of heat retention, water retention, and chemical reactions — the entire evolutionary chain breaks completely. A water‑world entirely covered by ocean can hold large amounts of water, but lacking contiguous land and combustible material, it cannot generate global wildfires. Both are inherently defective vessels, incapable of initiating the complete life cycle. Second tier: Core dynamic constraint. On top of a qualified vessel, terrestrial vegetation and extensive liquid surface water co‑exist over long periods, forming a water‑fire interweaving cycle that couples periodic global wildfires and torrential rains. High‑temperature wildfires first fracture complete mineral crystal lattices; then the thermal shock of rainstorms completes secondary deep fragmentation, generating massive quantities of highly active defect lattices with dangling bonds and charge vacancies — providing the sole material substrate for the assembly of biological macromolecules. Subsurface static aquifers can only support low, primitive plants; lacking large‑scale combustion and flushing cycles, they cannot evolve complex terrestrial animals on the surface. Third tier: Evolutionary outcome. Over billions of years of repeated water‑fire cycles, the fragmented lattices continuously adsorb, catalyze, and splice organic molecules; through natural selection and iteration, primitive cells with stable metabolism and self‑replication capabilities eventually emerge. This paper also designs a macroscopic control‑experiment framework using a ball and a cup, quantitatively deriving, from geometry and evaporation dynamics, the influence laws of concave water‑storage topography, planetary size, and stratigraphic clay adsorption on water‑retention duration — awaiting subsequent experimental measurements to complete the numerical values. The entire theory yields two major applications: reconstructing the screening criteria for exoplanetary habitability, ranking the integrity of the water‑storage vessel as the primary observational indicator; and establishing a scheme for evaluating and modifying target planets for interstellar migration, with naturally concave‑convex planets possessing both ocean basins and continents as the optimal colonization carriers. This paper integrates stellar nucleosynthesis, the Archean surface water‑fire cycle, biological evolution, and fossil‑fuel formation into a complete evolutionary sequence, all incorporated into the Fireball Cycle theory, thus filling the most fundamental underlying logic of the entire creation system