Ergonomics is the scientific study of human efficiency in a work environment. This discipline strives to optimize performance and maximize worker well-being. Human factors engineering involves the application of this knowledge to the design of the workplace, generally helping reduce muscle fatigue, increasing productivity, and reducing the likelihood and severity of work-related musculoskeletal disorders. In conventional workplaces, this, while not a simple task, is certainly manageable. In space exploration, however, ergonomics and mitigating the harm brought onto workers by their duties is far more complicated.
To understand this, just look at the workplace of the astronaut. The space environment is certainly unique. Besides the lack of oxygen, atmospheric concentration of dust on lunar and planetary surfaces, intense radiation from the Sun, hypergravity (gravitational forces greater than the 1 G felt on Earth) during dynamic phases of flight, hypogravity (ranging from partial-G on planetary surfaces to “zero G” in orbit) providing the feeling of weightlessness, noises, and vibrations, workers in space feel the impact of being separated from civilization for substantial lengths of time.
The combination of these out-of-this-world experiences makes the work environment for those in space exploration incredibly hazardous. This environment, particularly within the scope of its cognitive demands, is remarkably similar to that of someone on Earth in an extreme environment engulfed in danger. However, it is not enough for these individuals to simply stay alive; they have a job to do. The need to carry out complex work in this environment without compromising the mission or the health of the individuals brings up several key concerns with human factors.
Neurovestibular integration refers to the ability to orient the body, have effective movement, and respond to perceptual tasks. Those in space, due to the separation of their bodies from the two-dimensional movement established by the forces of gravity back on Earth, must learn to live in microgravity. Luckily, the human body adapts to living in microgravity over a short period of time, as the otolith organs and semicircular canals of the inner ear experience fluid shift.
The proprioceptive system, which aids and facilitates the information from the inner ear, must also adapt. Due to the lack of typical proprioceptive cues for sleeping, such as a pillow or regular bed, an individual’s sleep can detrimentally be affected in space. Personnel may also experience space motion sickness, an ailment similar to its terrestrial counterpart.
Also within the interest of neurovestibular integration concerns is visual acuity. Crewmembers have to cope with alternating bright light and deep shadows, due to the location of the Sun and darkness of space. In addition, on the lunar surface, the lack of atmosphere (even though there may be some atmosphere on the Moon) makes it difficult to estimate distance.
It is important to note that these issues, while certainly present during intravehicular activity (IVA), become far more severe during extravehicular activity (EVA), tasks that are also known as “space-walks”.
Effects on the Musculoskeletal System
In aerospace voyages, crewmembers often spend a great deal of time in the same place, without the exertion of the gravity by which humans have evolved. Due to the absence or alteration of weight, space travel results in a loss of protein that can lead to a decline in muscle density. Furthermore, it is not uncommon to experience changes in bone mineral density, muscle mass, and muscle function.
Furthermore, the mechanical stresses experienced during vibration, which may be present during a whole array of activities, can affect practically all body systems. Depending on the frequency, these vibrations have varying impacts, extending from just general discomfort to more extreme spinal damage. Whole-body vibration, an effect observed within machinery occupying seated persons in many other industries, exerts a negative impact on performance.
Effects on the Brain, Cognition, and Behavior
As with any occupational task, personnel performance in space travel is dependent on both the individual’s physical and mental health. Some of these concerns with cognition derive from physical issues. For example, increased acceleration and short-duration, rapid-onset forces lead to less blood flow to the brain, or cerebral hypotension. This can, in turn, contribute to “Almost Loss of Consciousness” (ALOC), a series of cognitive impairments associated with disorientation, poor word formation, and amnesia.
Psychological and psychiatric issues that emerge during long-duration human space flight fall under the focus of behavioral health and performance (BHP). As alluded to above, those involved with space travel must spend a significant period of time distanced from the entire world where all humans, plants, and animals have flourished. Issues with self-care and even concerns associated with conflict between crewmembers must be addressed.
Space Exploration and Posture
Posture is at the core of most human factors engineering processes. An individual’s posture, as it significantly influences performance and musculoskeletal health, must be encouraged to be its safest through the design of equipment and occupational practices. In space exploration, the severe effects to the musculoskeletal system and even mental health can negatively influence posture, which can further birth problems.
Ergonomic Solutions to Space Exploration Issues
Luckily, there has been significant work towards handling many of the ergonomic issues with aerospace occupations, and many individuals follow certain practices to accommodate for anticipated human factors. For example, to recreate some of the usual proprioceptive cues that index sleeping, crewmembers have reported using a bunched up piece of clothing attached to the sleep restraints to replicate a pillow, even though this is not needed in microgravity.
Furthermore, neurovestibular imbalances generally correct themselves over the course of just a few days, so it has been suggested that personnel wait to complete crucial mission events, such as EVAs, for a few days.
In addition, due to issues with deliriousness and disorientation associated with a few of the human factors concerns, some have suggested placing an importance on handles in spacecrafts. This was discussed in a 2005 paper published by SAE International, in which the authors noted that, in microgravity, people will grab almost anything to orient themselves, an activity that became problematic in 2004, when the Russian Aviation and Space Agency and NASA observed that an immensely inconvenient air leak in the International Space Station was likely caused by crew members using a hose near a window to orient themselves while taking pictures.
Because of this, the authors concluded that “Do Not Grasp” labels might be insignificant in preventing incidents such as the one referenced above, thus potentially rendering them ineffective in reducing equipment damage. Instead, the equipment should be designed while considering form that discourages grasping.
As for maintaining and preserving the musculoskeletal system, exercising is a clear solution. In the Zvezda Service Module, for example, there is the Treadmill with Vibration Isolation and Stabilization system, or TVIS, which is a highly effective countermeasure in reducing damage to the body. TVIS uses a spring loaded waist and shoulder harness to hold the crew on the treadmill, thus replicating the majority of their body weight.
Whole-body vibration is also a widely researched topic, and it is by no means a stranger to standardization. In fact, an ISO technical report, ISO/TR 10687:2022 – Mechanical vibration- Description and determination of seated postures with reference to whole-body vibration, addresses the risks that whole-body vibration carries for the human spine by summarizing quantities that are relevant for the assessment of related adverse health effects.
Human factors engineering issues associated with the mind are already managed as well. Cognitive assessments during long-duration space flight have been performed using the Cognitive Assessment Tool. Additionally, Behavior health and performance generally includes a set of activities that provide psychological services for astronauts, and they are carried out by operational groups from European Space Agency (ESA), Japan Aerospace Exploration Agency (JASA), NASA, and the Russia Federal Space Agency.
Lastly, but certainly not of minuscule value, there is the closed-loop life support systems of space crafts and space stations, which confine humans to a small area with recirculating air. This isolates personnel from many space-related hazards, since the system comprises habitats, suits, and vehicles is similar to a terrestrial closed system. In fact, the spacesuit is a marvel of space ergonomics, since it is made to be comfortable and compatible by applying anthropometry and other disciplines. However, these environments, while facilitating the growth of normal flora, can also help pathogenic bacteria and viruses grow, so they must be carefully managed.
While there has already been significant effort made for the human factors engineering and ergonomics of space exploration activities, there is always room for growth, especially with the current goals of space agencies throughout the world. Currently, space organizations in the United States, Russia, and China have planned manned missions to Mars, prompting the need for greater focus to be placed on space ergonomics.
The Human Factors and Ergonomics Society (HFES) is devoted to promoting the discovery and exchange of knowledge concerning the ergonomic design of systems that are tied with the characteristics of human beings. Much of the literature that you can discover related to the human factors engineering of space exploration has been produced, at least in conjunction with, HFES. For our Earthly workplace ergonomic concerns, HFES writes, develops, and publishes standards to be used for guidance. These include: