Modular Fission-Powered Surface Swarms for Atmospheric Compression and In-Situ Carbonation on Venus: A Near-Term Roadmap and Long-Term Fusion Integration.

Abstract This paper presents a paradigm shift in Venusian terraforming, moving from high-risk macro-engineering concepts to a resilient, decentralised Surface-First distributed engineering model. We introduce the framework of Dry Terraforming, which prioritises mechanical atmospheric sequestration over traditional chemical conversion. By utilising a swarm of modular, fission-powered surface processors operating via supercritical CO2 (sCO2) Brayton cycles, atmospheric carbon dioxide is mechanically compressed and reacted with basaltic regolith to form stable solid carbonates. A quantitative waste heat analysis confirms that greenhouse cooling from CO2 sequestration outpaces reactor waste heat by a factor of 8× at the Phase I target, resolving a potential concern in favour of the framework. Key Quantitative Estimates Total Energy Requirement: Approximately 4.8 × 1025 J for a 10% reduction in atmospheric mass, based on a conservative specific work constant Wspec = 106 J kg−1 decomposed into excavation, multi-stage CO2 compression, and mineral reaction activation. Continuous Power Output: Approximately 3.05 × 1016 W over a 50-year horizon. Deployment Scale: Roughly 3 × 108 modular 100 MW fission units; sensitivity analysis provided across durations of 25–200 years and unit sizes of 10–1000 MW. Thermodynamic Efficiency: Net efficiencies of 25–30% using the sCO2 Brayton cycle at surface conditions; up to 48.9% Carnot efficiency at 10 km altitude deployment sites. Regolith Availability: Required feedstock (~8.6 × 1019 kg of forsterite) is four orders of magnitude below the estimated Venusian crustal inventory — not a limiting constraint. Fissile Fuel: Once-through uranium cycles are insufficient at this scale; the thorium–MSR breeding cycle is identified as an essential design constraint, requiring only a seed inventory of fissile material transported from Earth. Waste Heat vs. Cooling: Reactor waste heat (~7.84 × 1016 W) represents ~1% of Venus’s existing greenhouse thermal budget. Net cooling begins after ~1% CO2 removal (≈ year 5), after which cooling outpaces waste heat by up to 16× by Phase I completion. New in Version 1.0.1 Full decomposition and justification of the Wspec assumption into three sub-process contributions Regolith availability check with quantitative crustal mass comparison Fissile fuel budget analysis and case for thorium–MSR breeding as an essential constraint Self-replicating manufacturing discussion with foundational references (von Neumann 1966; Freitas & Valdes 1985) Non-CO2 atmospheric components addressed (N2, SO2, HCl, H2SO4) Waste heat analysis section with four governing equations and a milestone summary table Four reproducibility figures generated via Octave scripts (included as supplementary material) Expanded bibliography: 13 references, including Lackner et al. (1995), Seifritz (1990), JANAF tables, NASA CEA database, Bullock & Grinspoon (2001), and NuScale VOYGR design documentation Researcher Notes & Disclaimer Note on Methodology: This work is a theoretical proposal authored by an independent researcher. The mathematical models and energy balances presented herein serve as order-of-magnitude engineering estimates. All calculations have been independently verified via Octave scripts included with this submission. Call for Review: These figures have not undergone formal peer review. The author welcomes further scrutiny, computational fluid dynamics (CFD) simulations, detailed mineralogical modelling, and atmospheric chemistry modelling from the scientific community to validate or refine the Wspec assumptions, deployment logistics, and greenhouse sensitivity estimates. Use of AI-Assisted Tools: The technical framework, calculations, and scientific conclusions were developed entirely by the author. Large language models (LLMs) were employed solely for linguistic refinement, grammatical revision, verification of calculations, and bibliographic review. All intellectual content and conclusions remain the sole responsibility of the author. Keywords: Terraforming, Venus, Fission, Fusion, Carbon Sequestration, ISRU, Brayton Cycle, Waste Heat, Mineral Carbonation, Molten Salt Reactor