This technical note presents a modular underground gravitational energy storage architecture designed for planetary settlements, with a primary focus on Mars applications. The system utilizes deep vertical boreholes combined with horizontal underground galleries to store large numbers of high-mass modules in a discharged (low-potential) state, enabling scalable, long-duration energy storage without reliance on surface gravity towers or water-based systems. The architecture emphasizes single-shaft amplification through lateral mass stacking, robotic underground handling, and interconnected gallery networks to maximize energy density per borehole while minimizing drilling requirements and surface footprint. Multiple deployment topologies are explored, including linear energy spines and circular energy rings surrounding settlement zones, enabling redundancy, fault isolation, and colony-scale integration. The system is intended to function as a resilient secondary and emergency energy buffer, complementing primary power sources such as solar arrays, nuclear baseload systems, and high-torque hydraulic energy systems developed by Planetary Energy Systems. Operational cycles, seasonal charging and discharge strategies, unmanned underground operation, and phased deployment from early outposts to mature city-scale settlements are discussed. This document is released as an open technical disclosure to establish prior art and to support further research, evaluation, and adaptation of gravitational energy storage systems for off-world infrastructure. The concepts presented are not limited to Mars and may be applicable to other planetary bodies, moons, or terrestrial environments where deep geological structures are available.
SAMUEL JAGGARD (Fri,) studied this question.