How do you keep a crew sane on a mission that might last years without a real horizon? This short documentary looks at the design problems facing spacecraft interiors, treating cabin layout as a psychological instrument rather than just an engineering constraint. Designers and researchers walk through specific choices that matter more than they seem: the shape of a chair, the color scheme on a wall, the placement of a window, all weighed for their effect on mood and stability during long-term confinement. The film frames the spacecraft cabin as a controlled environment where every surface is a variable in crew mental health, drawing on the same thinking behind submarine and polar-station design. It stays close to its subject, moving through the practical tradeoffs designers face when trying to make a small metal box feel livable for months at a stretch. The result is a compact look at a problem space agencies take seriously as missions get longer and farther from home.