Activity-based habitable volume estimating for human spaceflight vehicles

Accurate estimation of required working volumes is a vital aspect of the design process for any vehicle involving humans. This is all the more important when such a vehicle must serve as the crew\´s sole habitable volume during a mission of any duration in the harsh environment of space. The key to accurate estimation of required crew volumes is to properly analyze the volume necessary to perform the entire range of tasks that will be required of the crewmembers. This paper discusses activity-based estimation techniques and methodologies that lead to the determination of realistic, justifiable, and cost-effective habitable volumes for new spacecraft, which are physically safe and promote sustained behavioral health. The categories of activities considered include command and control, typical mission accomplishment, scientific, exercise/recreational, medical/health maintenance, food preparation/eating, group gatherings/entertainment, sleeping/privacy, clothing changes, EVA preparation, and personal hygiene activities. Each activity is assigned a volume derived from anthropometric "first principles" using position and motion studies together with accepted industry standards for crewmember sizes and ranges of motion. A matrix of the activities for each mission element is developed to show "nesting" or co-location possibilities. Where groups of activities can be reasonably nested, the activity requiring the largest volume is used for the habitable volume calculation, while the smaller nested volumes are accommodated in the process. Using these techniques and methodologies consistently results in substantial reductions in volume (thus mass) for each of the vehicles considered when compared with the recommendations based on NASA-STD-3000.