HELIOS: A Preliminary Systems-Engineering Framework for an Earth-Encircling Habitable Solar Ring

Concept-stage research framework (preprint, not peer-reviewed) for an Earth-encircling habitable solar ring. The paper distinguishes four physically different meanings of "ring" (continuous, segmented, independent objects, actively supported) and notes that a passive continuous ring is dynamically unstable. It reviews active-support concepts from the literature (Birch orbital ring, Lofstrom loop, tether hybrids) and gives order-of-magnitude scales for orbital speed, period, circumference, rotating-habitat radius and ring mass. It also includes a risk ranking, development gates and a problem register of 18 engineering workstreams with closure evidence. This is a research agenda, not a validated design or a proof of feasibility.