Multi-Target Encapsulation Architecture for Inactive Heavy Upper Stages: Passive Whipple Shielding and Drag Enhancement via Pneumatic Deployment

Abstract (da incollare nel campo Description) Active Debris Removal (ADR) programs in Low Earth Orbit (LEO) are historically constrained by the prohibitive operational cost of the conventional 1-to-1 retrieval model, where an interceptor vehicle expends extensive propellant to capture and de-orbit a single derelict target before being discarded. In this paper, we propose the Multi-Target Encapsulation Architecture (MTEA), a nautical-inspired, passive remediation paradigm. Instead of hunting distributed micro-fragments or relying on active propulsive descent, MTEA deploys an autonomous hybrid-propulsion tug to service multiple massive rocket stages (such as the Soviet SL-16/Zenit-2 cluster at i ≈ 71^∘) in a single campaign. The mechanism utilizes an axial radial-mandrel docked into the main engine nozzle, deploying an oversized, pneumatic multi-layer sleeve based on the principle of a nautical fyke net (nassa). Once cinched and pressurized, the resulting standoff capsule (D ≈ 14 m) provides dual functionality: an omnidirectional, flexible Whipple shield preventing secondary fragmentation from hypervelocity micro-impacts, and an engineered ballistic drag surface. The drastic increase in the Area-to-Mass ratio ($A/m$) exploits residual thermospheric friction to reduce passive orbital decay timelines from centuries to less than two decades. The mission design, aerodynamic passivity, megaconstellation transit safety, and a multilateral consortium economic model are systematically formulated.