Testing the Celentano Curve: An Empirical Survey of Predictions for Human Spacecraft Pressurized Volume

Abstract

This paper presents an analysis of the “Celentano Curve” that depicts a relationship between spacecraft pressurized volume and the duration of a space mission. In 1963, Celentano, Amorelli, and Freeman of North American Aviation described a set of curves that can predict the amount of pressurized volume necessary per crewmember to conduct a mission at “tolerable, performance, or optimal” levels. Since Yuri Gagarin flew in Vostok 1 in 1961, the US, Russia, and China have launched more than 250 human spaceflights. This paper collects this empirical data and tests the Celentano curves against it. In assessing the data this analysis takes a traditional statistical approach, stating the null hypothesis as no effect between mission duration and volume. It treats the Celentano plot of a quasi-logarithmic curve as the alternate hypothesis stating a causal relationship between mission duration and volume. Many researchers have published variations of the Celentano curve, and this paper considers nine of them as additional interpretations of the alternate hypothesis, plus three versions of the crew size alternate 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 with a coefficient of determination (R 2 value) of 72 percent and 60 percent respectively. Within the historic envelope of spaceflight experience of over a year in space, the volume trend does not level off but continues to rise.