For generations, spacecraft were engineered as sealed vessels of survival, their windows an afterthought in the calculus of keeping humans alive in the void. Now, as missions stretch toward the Moon and Mars, engineers are confronting a quieter truth: survival and well-being are not the same thing, and the human mind requires horizons as surely as the body requires air. The window, long treated as a structural liability, is being reimagined as essential infrastructure — a portal not just to space, but to psychological endurance.