Modeling Occupational Fingernail Onycholysis Disorders in the Population of US Astronauts Who Have Engaged in Extravehicular Activity

Objectives Spacesuits are designed to be reliable personal spacecraft that preserve the life and well-being of the astronaut from the extremes of space. However, materials, operating pressures, and suit design requirements often result in a risk of musculoskeletal discomfort and injury to various areas of the body. In particular, this investigation looked at fingernails and their risk of developing onycholysis. Methods An onycholysis literature review was followed by a retrospective analysis of injury characteristics, astronaut suited training and spaceflight events, hand anthropometry, glove sizing, and astronaut demographics. Multiple logistic regression was used to assess the likelihood of onycholysis occurrence by testing potential risk variables against the dataset compiled from the retrospective data mining. Results The duration of event exposure, type of glove used, distance (delta) between the fingertip and the tip of the glove, sex, and age were found to be significantly related to occurrence of onycholysis (whether protective or injurious). Conclusion An initial risk formula (model) for onycholysis was developed as a result of this investigation. In addition to validation through a future study, further improvement to this onycholysis equation and spacesuit discomfort and injury in general can be aided by future investigations that lead to better definition of the threshold between safe and risky exposure for each type of risk factor. Application This work described a potential method that can be used for EVA spacesuit glove onycholysis injury risk analysis for either iterative glove design or between glove comparisons, such as during a product downselect process.

3D virtual fit assessment and modeling: liquid cooling and ventilation garment

PurposeThe suboptimal fit of a spacesuit can interfere with a crewmember's performance and is regarded as a potential risk factor for injury. To quantify suit fit, a virtual fit assessment model was previously developed to identify suit-to-body contact and interference using 3D human body scans and suit CAD models. However, ancillary suit components and garments worn inside of the suit have not been incorporated.Design/methodology/approachThis study was conducted to predict a 3D model of the liquid cooling and ventilation garment (LCVG) from an arbitrary person's body scan. A total of 14 subjects were scanned in a scan wear and LCVG condition. A statistical model was generated using principal component analysis and random forest regression technique.FindingsThe model was able to predict the geometry of the LCVG layer at the accuracy of 5.3 cm maximum error and 1.7 cm root mean square error. The errors were more pronounced for the arms and lower torso, while the thighs and upper torso regions, which are critical for suit fit assessments, show more accurate predictions. A case study of suit fit with and without the LCVG model demonstrated that the new model can enhance the scope and accuracy of future spacesuit assessments.Originality/valueThe capabilities resulting from these modeling techniques would greatly expand the assessments of fit of the garment on various anthropometries. The results from this study can significantly improve the design process modeling and initial suit sizing efforts to optimize crew performance during extravehicular activity training and missions.

Revisiting decompression sickness risk and mobility in the context of the SmartSuit, a hybrid planetary spacesuit

Gas pressurized spacesuits are cumbersome, cause injuries, and are metabolically expensive. Decreasing the gas pressure of the spacesuit is an effective method for improving mobility, but reduction in the total spacesuit pressure also results in a higher risk for decompression sickness (DCS). The risk of DCS is currently mitigated by breathing pure oxygen before the extravehicular activity (EVA) for up to 4 h to remove inert gases from body tissues, but this has a negative operational impact due to the time needed to perform the prebreathe. In this paper, we review and quantify these important trade-offs between spacesuit pressure, mobility, prebreathe time (or risk of DCS), and space habitat/station atmospheric conditions in the context of future planetary EVAs. In addition, we explore these trade-offs in the context of the SmartSuit architecture, a hybrid spacesuit with a soft-robotic layer that, not only increases mobility with assistive actuators in the lower body, but it also applies some level of mechanical counterpressure (MCP). The additional MCP in hybrid spacesuits can be used to supplement the gas pressure (i.e., increasing the total spacesuit pressure), therefore reducing the risk of DCS (or reduce prebreathe time). Alternatively, the MCP can be used to reduce the gas pressure (i.e., maintaining the same total spacesuit pressure), therefore increasing mobility. Finally, we propose a variable pressure concept of operations for the SmartSuit spacesuit. Our framework quantifies critical spacesuit and habitat trade-offs for future planetary exploration and contributes to the assessment of human health and performance during future planetary EVAs.

Comparison of Display Modality and Human-in-the-Loop Presence for On-Orbit Inspection of Spacecraft

Objective To investigate the impact of interface display modalities and human-in-the-loop presence on the awareness, workload, performance, and user strategies of humans interacting with teleoperated robotic systems while conducting inspection tasks onboard spacecraft. Background Due to recent advancements in robotic technology, free-flying teleoperated robot inspectors are a viable alternative to extravehicular activity inspection operations. Teleoperation depends on the user’s situation awareness; consequently, a key to successful operations is practical bi-directional communication between human and robot agents. Method Participants ( n = 19) performed telerobotic inspection of a virtual spacecraft during two degrees of temporal communication, a Synchronous Inspection task and an Asynchronous Inspection task. Participants executed the two tasks while using three distinct visual displays (2D, 3D, AR) and accompanying control systems. Results Anomaly detection performance was better during Synchronous Inspection than the Asynchronous Inspection of previously captured imagery. Users’ detection accuracy reduced when given interactive exocentric 3D viewpoints to accompany the egocentric robot view. The results provide evidence that 3D projections, either demonstrated on a 2D interface or augmented reality hologram, do not affect the mean clearance violation time (local guidance performance), even though the subjects perceived a benefit. Conclusion In the current implementation, the addition of augmented reality to a classical egocentric robot view for exterior inspection of spacecraft is unnecessary, as its margin of performance enhancement is limited in comparison. Application Results are presented to inform future human–robot interfaces to support crew autonomy for deep space missions.

Modular Robotic Limbs for Astronaut Activities Assistance

In order to meet the assist requirements of extravehicular activity (EVA) for astronauts, such as moving outside the international space station (ISS) or performing on-orbit tasks by a single astronaut, this paper proposes an astronaut robotic limbs system (AstroLimbs) for extravehicular activities assistance. This system has two robotic limbs that can be fixed on the backpack of the astronaut. Each limb is composed of several basic module units with identical structure and function, which makes it modularized and reconfigurable. The robotic limbs can work as extra arms of the astronaut to assist them outside the space station cabin. In this paper, the robotic limbs are designed and developed. The reinforcement learning method is introduced to achieve autonomous motion planning capacity for the robot, which makes the robot intelligent enough to assist the astronaut in unstructured environment. In the meantime, the movement of the robot is also planned to make it move smoothly. The structure scene of the ISS for extravehicular activities is modeled in a simulation environment, which verified the effectiveness of the proposed method.

Reducing Metabolic Cost During Planetary Ambulation Using Robotic Actuation

INTRODUCTION: Current spacesuits are cumbersome and metabolically expensive. The use of robotic actuators could improve extravehicular activity performance. We propose a novel method to quantify the benefit of robotic actuators during planetary ambulation.METHODS: Using the OpenSim framework, we completed a biomechanical analysis of three walking conditions: unsuited, suited with the extravehicular mobility unit (EMU) spacesuit (represented as external joint torques applied to human joints), and suited with the EMU and assisted by robotic actuators capable of producing up to 10 Nm of torque. For each scenario, we calculated the inverse kinematics and inverse dynamics of the lower body joints (hip, knee, and ankle). We also determined the activation of muscles and robotic actuators (when present). Finally, from inverse dynamics and muscle activation results, the metabolic cost of one gait cycle was calculated in all three conditions.RESULTS: The moments of lower body joints increased due to the increased resistance to movement from the spacesuit. The additional torque increased the overall metabolic cost by 85 compared to the unsuited condition. The assistive robotic actuators were able to reduce the metabolic cost induced by EMU resistance by 15.DISCUSSION: Our model indicates that the majority of metabolic cost reduction can be attributed to the actuators located at the hip. The robotic actuators reduced metabolic cost similar to that of modern-day actuators used to improve walking. During a Mars mission, the actuators could save one crewmember up to 100,000 kilocal on one 539-d planetary expedition.Kluis L, Keller N, Bai H, Iyengar N, Shepherd R, Diaz-Artiles A. Reducing metabolic cost during planetary ambulation using robotic actuation. Aerosp Med Hum Perform. 2021; 92(7):570578.

Planetary extravehicular activity (EVA) risk mitigation strategies for long-duration space missions

Extravehicular activity (EVA) is one of the most dangerous activities of human space exploration. To ensure astronaut safety and mission success, it is imperative to identify and mitigate the inherent risks and challenges associated with EVAs. As we continue to explore beyond low earth orbit and embark on missions back to the Moon and onward to Mars, it becomes critical to reassess EVA risks in the context of a planetary surface, rather than in microgravity. This review addresses the primary risks associated with EVAs and identifies strategies that could be implemented to mitigate those risks during planetary surface exploration. Recent findings within the context of spacesuit design, Concept of Operations (CONOPS), and lessons learned from analog research sites are summarized, and how their application could pave the way for future long-duration space missions is discussed. In this context, we divided EVA risk mitigation strategies into two main categories: (1) spacesuit design and (2) CONOPS. Spacesuit design considerations include hypercapnia prevention, thermal regulation and humidity control, nutrition, hydration, waste management, health and fitness, decompression sickness, radiation shielding, and dust mitigation. Operational strategies discussed include astronaut fatigue and psychological stressors, communication delays, and the use of augmented reality/virtual reality technologies. Although there have been significant advances in EVA performance, further research and development are still warranted to enable safer and more efficient surface exploration activities in the upcoming future.

Electrical Shock Hazard Severity Estimation During Extravehicular Activity for the International Space Station

INTRODUCTION: Research has shown that astronauts performing extravehicular activities may be exposed, under certain conditions, to undesired electrical hazards. This study used computer models to determine whether these undesired induced electrical currents could be responsible for involuntary neuromuscular activity caused by either large diameter peripheral nerve activation or reflex activity from cutaneous afferent stimulation.METHODS: A multiresolution variant of the admittance method along with a magnetic resonance image millimeter resolution model of a male human body were used to calculate the following: 1) induced electric fields; 2) resistance between contact areas in a Extravehicular Mobility Unit spacesuit; 3) currents induced in the human body; 4) the physiological effects of these electrical exposures; and 5) the risk to the crew during extravehicular activities.RESULTS: Using typical EMU shock exposure conditions, with a 15V source, the current density magnitudes and total current injected are well above previously reported startle reaction thresholds. This indicates that, under the considered conditions during a spacewalk in the charged ionospheric plasma of space, astronauts could experience possibly harmful involuntary motor response and sensory pain nerve activation.Hamilton DR. Electrical shock hazard severity estimation during extravehicular activity for the International Space Station. Aerosp Med Hum Perform. 2021; 92(4):231239.