Vehicle Restraint Considerations for Commercial Spaceflight

There are currently no direct regulations and few guidelines regarding restraint design for commercial spaceflight vehicles. Operators designing vehicles intended solely for private commercial use, particularly short-duration suborbital flights, have questioned the need for 5-point restraints, instead considering the options of fewer restraints and less stringent application requirements. We sought to identify risks and benefits of alternative restraint designs for the commercial spaceflight industry, particularly for the diverse population of commercial spaceflight participants (SFPs). A systematic review was conducted on currently available information and published literature of human and animal studies as well as industry standards regarding restraint design, common injuries, and patterns of injuries in vehicular trauma, including automobile, aircraft, and spacecraft. Although data are lacking regarding commercial spacecraft or potential mishap forces, extensive studies are available in analogue environments, including motor vehicle crashes and aviation mishaps, which demonstrate variations of restraint design and relative risks and benefits of these systems. These studies demonstrate superiority of harnesses that include shoulder restraint and a negative-G (crotch) belt to limit torso movement. Injury patterns in anthropometrically varied populations, with factors including gender, obesity, and advanced age, demonstrate increased vulnerability to morbidity and mortality in obese and elderly populations and improved outcomes with more rigorous restraint designs. Given the varied population anticipated for commercial SFPs and significant reduction in morbidity and mortality associated with 5-point restraint designs, evidence suggests that the use of a 5-point restraint is most appropriate for commercial spacecraft.