In 1963, Celentano, Amorelli, and Freeman of North American Aviation described a set of curves as an Index of Habitability that can predict the amount of pressurized volume necessary per crewmember to conduct a mission at “tolerable, performance, or optimal” levels. This paper presents an analysis of the “Celentano Curve” that depicts a relationship between spacecraft pressurized volume and the duration of a space mission.
Since Yuri Gagarin flew in Vostok 1 in 1961, the US, Russia, and China have launched more than 250 human spaceflights. This survey collects the empirical data and tests the Celentano curves against it. The statistical approach treats the Celentano curve as the hypothesis stating a causal relationship between mission duration and volume. Many authors have published variations of the Celentano curve, and this author considers nine interpretations, plus three versions of the crew size hypothesis and one functional operations hypothesis.
This analysis shows that pressurized volume increases as a function of mission duration, both as a power curve and a logarithmic curve. This volume trend does not level off but continues to rise throughout the historic envelope of human spaceflight.
