Justification of Crew Function and Function Capability for Long Duration Deep Space Habitation

There are currently no established standards or guidelines that define the functions to be present in habitats for use beyond Low Earth Orbit (LEO), or for the capabilities of those functions. There is limited human experience with long duration space habitation, none of which is beyond LEO. There is significantly less experience with even short duration human habitation beyond LEO. Studies since the Apollo program that have proposed long duration habitats have applied inconsistent functionality, yet these functions have substantial implications for spacecraft mass and volume. There are also numerous aspects of human space flight beyond LEO that have implications for these functions. This paper develops a method for design teams to identify and justify the functions and capabilities to include in long duration habitats intended for use beyond LEO. Finally, human-in-the-loop testing methods are recommended for use in the early spacecraft design stages to ensure that the habitat will successfully provide the intended functions and capabilities.