Premise and audience benefit: readers will learn why radiation protection—not just artificial gravity—forces the Stanford Torus into a two-body architecture. Build a concise answer to the question “Why is the Stanford Torus’s radiation shield separate from its rotating habitat?” Establish the 1977 Stanford Torus baseline first, then use the study’s approximately 9.9-million-tonne passive shield figure to explain why rotating the shield would create unacceptable structural stress. Briefly connect that consequence to the narrow 1–2 metre gap, relative motion near 100 m/s, and the need for positive positioning. Keep the central trade-off clear: less shielding mass versus tighter mechanical tolerances. Do not imply the design was built or fully validated.

## Why was the Stanford Torus’s shield separate? In the 1977 design study, the Stanford Torus was a proposed wheel-shaped habitat roughly 1,800 metres across, with a 130-metre-diameter inhabited tube rotating at about 1 rpm to simulate gravity. Radiation protection forced it into a two-body archit...