We know that decor assumes more or less importance depending on the conditions of confinement. Although people differ in what they consider desirable, there seems to be an almost universal aversion to environmental uniformity, along with some evidence that, over time, people seek greater complexity in the environment. In the closed environment of space, it will be necessary to test tolerances to both differences and sameness in design. Flexibility is likely to be fundamental to any spacecraft design. However, even this recognized value will have its limits, since a living environment must provide an opportunity for stability as well as for adventure.
Lighting offers an opportunity for rapid environmental shifts.
Just how lighting can and should be used, both from a design and a performance perspective, requires further investigation. To date, olfactory adaptation in spaceflight has apparently kept ahead of olfactory buildup. However, odors may present problems in future flights, especially when humans and experimental animals share the same living area, and when new crewmembers are rotated into the closed environment. We need to determine tolerance levels for various odors and to understand more fully how odors work in concert. Noise problems are among the more serious habitability concerns of long duration spaceflight.