Spacecraft Occupant Protection Requirements: A Review of the Recent Changes

Abstract

NASA has recently updated spacecraft design requirements for protecting crewmembers during dynamic spaceflight phases. The details of the update are available in a NASA publication (NASA TM-2013-217380) and are summarized here. Previously, NASA's occupant protection requirements relied primarily on the multiaxial dynamic response criterion, which NASA refers to as the Brinkley Dynamic Response Criteria (BDRC). Although simple to implement, there are several important ground rules that must be met for the injury predictions to be applicable. These include proper restraint, flail controls, proper seating support, pressure suit considerations, head protection including consideration of helmet mass, and spaceflight deconditioning. Even if these ground rules are met, there are limitations to the model that must be addressed, including: model validation, sex differences, age effects, anthropometry effects, and differences between the physical fitness of military test subjects and future crewmembers. To address these limitations, new injury assessment reference values (IARV) have been prescribed for the 5(th) percentile female and 95(th) percentile male Hybrid III anthropomorphic test devices (ATD). These metrics are head-injury criterion, head-rotational acceleration, neck injury criterion, neck-axial-force limits, flail prevention, and lumbar-axial compression force. Using these new ATD IARVs, NASA can have increased confidence that vehicle designs mitigate the risk of injury during dynamic phases of flight.

A comparative study on dynamic stiffness in typical finite element model and multi‐body model of C6–C7 cervical spine segment

“…Neck injuries were common in traffic accidents and aviation lifesaving, which brought heavy economic burden to the societies [1][2][3][4][5][6]. Numerous efforts had been put into developing head-neck complex models to study biomechanism of such injuries because comprehensive biomechanical models including finite element models and multi-body models have many advantages [2,[7][8][9][10][11][12][13][14].…”

Computational Assessment of Positional Sensitivity to Injury in Spacecraft Occupants

“…Females have a lower tolerance to neck compression forces and are thus at an increased risk to neck injury (Somers, Gohmert, & Brinkley, 2014). A spacecraft occupant may experience further neck compression if they are required to wear a helmet (Somers, Newby, et al, 2014).…”

Investigation of the THOR Anthropomorphic Test Device for Predicting Occupant Injuries during Spacecraft Launch Aborts and Landing

“…However, the BDRC has limitations (Somers et al, 2013 ). It only predicts ranges of injury risk and cannot provide information as to the severity or anatomical location of an injury.…”