Engaging space: extraterrestrial architecture and the human psyche

Acta Astronautica 56 (2005) 980 – 995 www.elsevier.com/locate/actaastro

Engaging space: extraterrestrial architecture and the human psyche夡 Angel Marie Seguin MAIBC, M. Arch., B.E.D., Intern Architect, Canada Available online 17 March 2005

Abstract The human fascination with exploring and inhabiting the space that lies beyond Earth’s atmosphere continues to grow. Nevertheless, 40 years of experience to date have clearly established that humans in outer space routinely suffer significant psychological impairment arising from their stressful extraterrestrial living conditions. This paper explores those extraterrestrial conditions through the interactions between the extraordinarily harsh environment of outer space, the sensations that humans encounter in space, and the qualities of a habitat that physically interposes itself between the two. The objective of this paper is to develop a habitat that expresses the extraterrestrial condition while supporting the mental health of its inhabitants, so as to augment the success of prolonged extraterrestrial residence and interplanetary travel. © 2005 Elsevier Ltd. All rights reserved.

1. Introduction 1.1. Background Since the 1960s, exceptional individuals have met the challenges of the extraterrestrial experience; the majority of those people have survived, but not without enduring significant hardships from the unnatural living conditions of outer space and the extraterrestrial architecture of the day. Mankind now stands at

E-mail address: [email protected]. For a much more extensive collection of research, analysis, and description of the topics presented within this paper, please consult the thesis library at the University of Calgary, Faculty of Environmental Design for the author’s thesis. 夡

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the threshold of long-duration space habitation and interplanetary travel. However, such missions are jeopardized by the negative psychological effects of the extraterrestrial experience on space travellers. As one Russian cosmonaut wryly remarked during a mission debriefing, “All the conditions necessary for murder are met if you shut two men in a cabin measuring 5 m by 6 m and leave them together for two months” [1]. The space industry has come to recognize the importance of mentally stable space travellers and much knowledge has been gained regarding the psychological dysfunction that can arise during a space mission. However, progress in redesigning the habitat accordingly has been slow to date, due to a lack of funding rather than a lack of ability. Astronauts and cosmonauts are still expected to largely adapt to their

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extraterrestrial conditions and as space missions become increasingly prolonged, the resulting psychological issues threaten to loom largest over the success or failure of long duration space excursions [2]. 1.2. Objective The objective of this paper is to define a new approach to human space habitation that adapts extraterrestrial architecture to the basic human needs of the occupants rather than perpetuating the frequently unsuccessful attempts of humans to adapt to the hostile conditions of outer space. The habitat is a self-sustaining, orbiting space station that will house humans, animals, and other organic matter for long-duration habitation, while promoting the mental health and psychological well-being of the crew aboard. The facility will be a platform for research and exploration, and a departure point for interplanetary travellers. The proposed station will accommodate 300–500 people for years or decades at a time, bordering on orbital colonization, and will probably be technologically feasible in the near future, perhaps as soon as 2020.

2. The design challenge Our terrestrial existence of approximately 65 million years has by necessity attuned us physiologically and psychologically to the Earth’s peculiar environmental conditions, as well as its cyclic and stimulating attributes [3]. It is therefore not surprising that most people have difficulty adapting to life in space because it is so foreign to our very existence. In fact, the extraterrestrial experience can be psychologically overwhelming for even the best of us. The extraterrestrial condition is experienced in two ways. One is the well-documented and somewhat incapacitating psycho-physiological stressors such as loss of hearing, smell, taste, visual acuity and depth perception [4]; loss of bone density and muscle mass [5]; weightlessness [6]; motion sickness [7,8]; the everpresent risks of sudden depressurization [9,10]; excessive radiation [11,12] and collisions with other matter [13]. Second are the psycho-environmental stressors that are contributed by elements of the current spacecraft

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designs. Surprisingly, “most volunteers for anything as challenging and unusual as space, undersea habitats and polar work will score toward the upper end of any scale of thrill-seeking, novelty-seeking, competence/effectance motivation and similar dimensions, they want adventure and challenges. Many discover only too soon that they have committed themselves to monotonous, routine, boring tasks in a monotonous, confining environment, cooped up with the same unvarying group, and they cannot get out” [14]. The conditions within a spacecraft are very different from earthly shelters. The majority of the spacecrafts are small, confining, “on the no-frills side: stark, monochromatic, inflexible and hard,” and provide little stimulation or personal private space [15]. As well, there is no change in temperature, no breeze, no climatic or seasonal changes. Adding to the environmental monotony is the lack of variation in internal light levels with little or no natural sunlight to indicate the passage of time, if one could somehow synchronize to 16 light/dark cycles in a 24-h period (circadian rhythm dysfunction [16,17]). In addition to adjusting to their new environment, astronauts are routinely required to perform many demanding tests and experiments under a rigorous time schedule and in the almost uninterrupted presence of others (social tedium [18,19]), all the while being physically isolated from their comfortable and stimulating home and loved ones. Such restrictive environments defy the human need for a sense of freedom, the ability to come and go as they please, and the ability to choose an environment that suits their present emotional state. Without that sense of freedom, humans can experience “cabin fever” or feel “stir crazy”, a dysfunctional psychological state that is acted out in mood disorders such as anxiety, depression and withdrawal, and results in impaired judgement and decision-making [20]. The monotony of such invariant habitats significantly degrades astronauts’ psychological effectiveness in space and can possibly lead to “long eye”, where one suffers from memory loss, different identities and performs irrational acts [21,22]. Sensory deprivation is so incapacitating and psychologically destructive that it is a recognized method of interrogation and torture [23,24]. In addition, the sleep and sexual deprivations of extended space habitation cannot help matters [25,26].

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Ironically, the sensory overload that is also common aboard a spacecraft does not compensate for the effects of the sensory deprivation, but rather accentuates them. Noise and vibration that are generated by motors, pumps, valves, regulators, transformers, oscillators, fans, firing thrusters and other onboard equipment produces significant annoyance and fatigue for the crew [27]. As an indicator of the noise level in question, the average decibel level aboard the ISS ranges from 72.5 to as high as 74 dB [28]. Even in the quietest areas aboard the station, the design goal of 50–55 dB has been significantly exceeded. To put this noise level into perspective, a very busy city street produces an average of 70 dB [29]. The sum of these stressors renders the current extraterrestrial experience potentially overwhelming to the human psyche. The psychological imbalances and dysfunctions that manifest themselves in humans during spaceflight include boredom, lack of motivation, loneliness, withdrawal, depression and paranoia. These negative psychological effects lead to interpersonal conflicts as well as impaired judgement and decision-making, all of which jeopardizes the safety of the crew, the success of the mission and the validity of any research that is conducted during the mission. The extraterrestrial experience is so challenging and exhausting that upon their return from a space mission, all astronauts and cosmonauts are provided a protracted absence from their normal duties in order to recover. Dr. Albert W. Holland, the Chief Psychologist at NASA, stated that after post-flight debriefing and depending on the individual’s needs, all astronauts are given about 1 week for rest, emotional recovery and physical rehabilitation for every month in orbit. The RASA provide even more time off for its cosmonauts. Depending on the mission’s rigors and the particular circumstances of the individual, some astronauts remain emotionally drained for several months more and take some time off after all the post-flight medical tests, experiment data collection and media events are done, before returning to office duties or flight status [30]. Significant progress has been made to improve the live/work condition in outer space, but it has been a slow process due to budget restrictions and cutbacks. Clearly, much more needs to be done to improve the situation in light of the increasingly longer space missions that humans face in the years ahead.

3. The design intervention 3.1. The mission The proposed structure is a self-sustaining orbiting space station intended to be used for research, space exploration and interplanetary travel, and as an experimental platform for the future colonization of outer space. To maximize the mission success aboard this station, its design goes beyond providing the minimum life-support systems and physical amenities required to survive in space, as these elemental aspects of a space station are assumed to be incorporated into the proposed design, and the design focus for the purpose of this project is to develop positive and beneficial “qualities” of the extraterrestrial habitat that will sustain the mental health of its long-term occupants. As indicated earlier, there is a clear need for space travellers to engage in a more human environment in their habitat, one that provides a sense of normalcy and sufficient stimulus. The proposed design humanizes the habitat by implementing artificial gravity, incorporating spatial and volume variations with vistas of both the interior and exterior, and allowing in filtered sunlight for the purposes of communicating the passage of time with day/night cues to abet the human circadian rhythm. Further humanization of the habitat is provided through sensory variation and stimulus, such as providing light and shadow characteristics, consideration for the olfactory and gustatory senses, and distinctly private spaces. For the purposes of this project, the cultural norms that were incorporated into the habitat’s design are primarily North American; however, it is fully recognized that a much broader range of relevant cultures would need to be taken into account if this design were to be implemented. Throughout the design process, the main objective was to provide an environment that mitigates the negative psychological effects of long duration space habitation. To achieve such an environment, the objective was to strike a balance between the natural terrestrial state of humans and the desired extraterrestrial condition; in other words, to design an environment that would adequately sustain the terrestrial human condition while at the same time enabling the inhabitant to engage in the unique extraterrestrial experience. The intent is to assist the occupants of the space station to relate to and begin to understand their new

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Fig. 1. Basic form of the proposed habitat.

circumstances within a reasonably comfortable and familiar environment that will alleviate any undue stress. Perhaps the greatest design challenge was to provide a somewhat familiar environment that evokes a perception of “association” with the earthly condition, but without creating a simulation of the Earth’s environment. For discussion purposes, the station is assumed to be orbiting Earth; however, it could just as easily be in orbit around the Moon, Mars, or any other celestial body that is of interest to the human race. 3.2. Design description The essential form of the space station consists of two torus shapes that are each 1 km in diameter and joined at right angles. The first torus is almost complete with the exception of a small gap, and is referred to as the primary torus. The second torus subtends an angle of less than 180◦ and is referred to as the secondary torus. The two tori are joined to form a spherelike form (Fig. 1). The point at which the tori merge forms the central hub comprising the bridge, the observation deck, and other decks. Opposite the central hub on the primary torus are two transverse projections that form the transverse decks. The station is designed to ac-

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commodate 300–500 people comfortably with such amenities as private living quarters, workstations and labs, recreational, social and sport facilities, medical and educational facilities and more (Fig. 4). The organization or functional programming of the station envisions the primary torus as the main habitation area and the secondary torus as the support facilities. Within the main habitation area are the living quarters, workstations and labs, social, recreational and communal support facilities including access to the central hub, transverse decks and secondary torus, and all of these areas are connected by a common passageway or “street” (Fig. 6). On the primary torus, the “work area” consisting of labs and workstations is physically separated from the living area (the private quarters) by positioning each area on opposite sides of the central hub and the transverse decks (Fig. 1). The organization of the secondary torus is less complex. Not a complete half donut in shape, the secondary torus extends 13 above and 23 below the central hub (Fig. 1). In the upper portion of the secondary torus are the medical and educational facilities, including supplies. Most of the lower portion of the secondary torus is occupied by engineering, while laundry, waste management and maintenance are located closest to the central hub (Fig. 4). The two docking areas are located at the form’s geometric centre, at the interior end of the transverse decks, directly across from and in perfect view of the bridge or central hub. Having the docking areas located at the centre allows vessels to arrive and depart with minimal manoeuvring. Opposite the docking areas, at the exterior end of the transverse decks, are the spa and sport facilities (Fig. 1). In the central hub, the bridge is located toward the inside of the sphere-like form and faces the transverse decks. The security deck is positioned directly below the bridge with some recreational/social facilities and the mess hall and kitchen are below that. Further down is the zero deck and then the observation deck that faces toward the outside of the sphere-like form (Fig. 4). 3.3. The form The form arose from the extraterrestrial environmental conditions (the “site”), and from the human experience in and reaction to that unique site. As noted

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earlier, issues such as weightlessness, radiation, lack of air and atmospheric pressure, the various physical metamorphoses one undergoes and the disruption of the human circadian rhythm all fed into the development of the proposed design. The result is a form that optimally balances the naturally evolved human way of life on Earth with the very foreign way of life in space. 3.4. Artificial gravity For long-duration residence in space, it is imperative to provide artificial gravity in order to reduce the physical deterioration of the human body. In addition to the overt physical benefits, artificial gravity also enables the occupants’ olfaction, gustation and mobility to operate in a more “normal” manner, reducing their psycho-physiological stressors [5,8,11,12]. In space, the perception of gravity is created simply by exploiting the fundamental equivalence of gravity and acceleration: artificial gravity is generated by steadily rotating the structure about its central axis to continually accelerate the station’s occupants. The rotation creates a (centrifugal) force that directs the occupants toward the outside of the station; the rigid structure of the station in turn provides an equal and opposite (centripetal) force directed toward the station’s centre, which is perceived by the occupant as “gravity.” The greater the rate of revolution (rpm) and the radius of the station, the greater the force of artificial gravity will be experienced by the occupants [31]. 3.4.1. Primary rotation The proposed space station design rotates the primary torus about the “A” axis at a rate of 1 rpm to generate a force equivalent to 56% that of Earth’s gravitational pull, or “0.56G” (Fig. 2). Aboard the secondary torus, the perceived gravity varies from 0.56G at the central hub to negligible G at the point where the arms of the secondary torus meet the “A” axis. Although studies have shown that water will run downstream and human mobility functions are satisfactory at 0.3G [32], the station design features a higher perceived G-force than that because its occupants will move about within the station. In fact, the inhabitants will move at variable speeds in all different directions, and the design of the station’s artificial

Fig. 2. Dual rotation to generate artificial gravity and regulate the day/night cycle.

gravity needs to properly account for this reality and build in an appropriate safety factor. If a person were to run in the “street” of the space station in the direction opposite to that of rotation (or in a “retrograde” direction) and at the same speed as the habitat is rotating, that person would experience weightlessness because no net force would be acting on him or her. Conversely, if a person were to run “prograde” (in the same direction as the station’s rotation), that individual would experience a greater force of gravity because he or she would be revolving around the station’s centre at a rate faster than the station’s own 1 rpm. Therefore, in order to maintain an adequate artificial gravity of not less than 0.3G despite predicted movements of up to 15 km/h by the occupants aboard the station, a force of 0.56G is maintained for this design. Dizziness and disorientation from the Coriolis effect was cause for concern as it might make the people aboard experience balance awkwardness or motion sickness. However, because the occupants of the proposed space station are for the most part oriented parallel to the direction of the centrifugal force and not perpendicular to it (as is the case on a merry-go-round),

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they should generally not experience the Coriolis effect. Even in situations where an occupant is perpendicular to the centrifugal force, such as lying in bed, the station’s 500 m radius meets the recommended 1–2 km diameter minimum to prevent the occupants from feeling any discomfort [33]. As well, studies have indicated that a rotational speed of 1 rpm or less will essentially eliminate motion sickness, “Coriolis sickness,” or any other disorienting effects [34]. There is no concern that occupants might experience blurred vision of their external environment when travelling at a rotational speed of 188 km/h. Even on Earth, we are all hurtling through space on a sphere that orbits the Sun while also rotating at a surface speed of 1674 km/h, yet the stars around us appear so immobile that they are routinely used as navigational references for those who travel on land, at sea and in the air. Therefore, the occupants of the proposed space station would be expected not to experience blurred views of their external environment or any other similar ill effect from the speed of the station’s rotation.

3.4.2. Directional cues A change in the artificial gravity may cause a conflict between a person’s kinaesthetic sense and visual sense. Such a change in the centrifugal force would affect the body’s vestibular sensory system, yet the eyes may not report a corresponding change to the environment. This conflicting sensation may cause a slight queasiness, and is most likely to arise when an occupant changes his or her direction of movement from prograde to retrograde or vice versa aboard the rotating structure. Earth’s diameter is so massive (12,756 km) and its circumference is moving so fast (1674 km/h) that we do not experience any disorientation resulting from changes in our direction of movement because the resulting change in G-force is negligible. However, on a smaller vessel such as the proposed space station, a change in the occupants’ direction would become noticeable. For example, an individual walking prograde at a speed of 5 km/h would have a rotational velocity of 193 km/h (=188 + 5). If that person turns quickly and walks retrograde at the same speed, the individual would feel a slight reduction in the sensation of gravity because of his or her reduced rotational velocity of only 183 km/h (=188 − 5). The loss of 10 km/h

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(=193 − 183) in rotational speed causes a decrease of roughly 10% in the force of artificial gravity experienced by that person at that time. To determine what amount of change in G-force would be considered comfortably tolerable, an experiment was conducted, which concluded that up to a 10% change is acceptable. While others have assumed a higher level of tolerable change in G-force (for example, Hill & Schnitzer adopted a limit of 15% [35] and Stone used a figure of 25% [35]), there does not appear to be any particular basis for these figures and their legitimacy has been presented as questionable [35]. Therefore, the proposed design is based on a parameter that is conservatively estimated and has been experimentally derived. The most pronounced instances of conflict between kinaesthesis and visual perception would arise during a sport or exercise activity or during an emergency situation. Under these circumstances, a person aboard the space station would be travelling at speeds greater than 5 km/h and rapidly changing directions, only to stumble, fall, or feel ill because of the increased change in G-force experienced by the individual. Not knowing their direction of motion relative to the habitat’s rotation would prevent the occupants from co-ordinating their motions properly and adapting to the environmental conditions of the space station, resulting in such consequences as stumbling or nausea. If the crew knew and understood the station’s direction of rotation at all times, they could better function within their environment and anticipate kinaesthesis-visual anomalies, thereby alleviating undue psychological stress and confusion. Directional cues regarding the station’s rotation therefore appeared to be a necessary component of designing the habitat to sustain the psychological stability of its occupants. Dr. Holland and Theodore W. Hall have both reinforced the need for directional cues. Each expert indicated that such directional cues are extremely effective because keeping the inhabitants passively oriented to the rotation of their habitat would enable them to prepare themselves for the vestibular consequences of their actions [31,36]. For this design, directional cues were selected for the intuitive, visceral link between one’s psychological perception of a colour and one’s physical experience when moving aboard the space station. When moving prograde, one would feel an increase in exertion

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as the G-force rises: the intense and active colour red is therefore well suited to communicate that direction of motion. When moving retrograde, one would literally feel “light-hearted” as the G-force drops, so the calming, tranquil colour green is equally appropriate for that direction of motion [37]. The colours red and green are therefore judiciously applied throughout the vessel to readily indicate the prograde and retrograde directions of motion to the occupants. Other possible approaches for communicating direction aboard the station include the use of cool colours like blue for receding surfaces and warm colours like yellow for advancing surfaces, the use of wall mounted converse and convex shapes to symbolize the direction of rotation, or the use of more literal graphical indicators on the walls [36]. 3.4.3. Inertial balance To efficiently rotate an object like the proposed space station, the form’s weight needs to be symmetrically distributed about its axis of rotation. If a rotated object is not symmetrically balanced, it will translate from its original position. Another drawback of an unbalanced rotating object is that it requires more energy to keep it spinning because some of the object’s energy is diverted into other modes of motion such as translation or wobble. To maintain the station’s desired orbit and rate of rotation with minimal fuel consumption, the form of the station was designed to achieve inertial balance without being completely symmetrical. The reason for the asymmetrical approach was to provide different vantage points for its occupants and to create for them a variety of visually stimulating vistas of the overall structure. 3.5. Day/night cycle It is also necessary to maintain the human circadian rhythm to minimize or eliminate the disruptive sleep habits and “free cycling” that normally occurs during residency in space [16,38,39]. Therefore, a study was undertaken of the various types of available orbits (altitude, path and inclination) and of the various parameters within the extraterrestrial environment that can be manipulated to create a more normal and desirable day/night cycle for the habitants aboard.

The easiest way to produce a 24-h cycle akin to the day/night cycle on Earth is to place the space station in a geosynchronous orbit; however, such a placement would be hazardous to the occupants and was therefore considered unsuitable for the purposes of this project. A stable Geosynchronous Earth Orbit (GEO) is restricted to an altitude of approximately 36,000 km above the Earth’s surface, which also happens to coincide with the presence of the second or outermost Van Allen Belt region [40]. If a space station were to be placed in such a GEO, not only would its occupants be exposed to dangerous levels of radiation, but travelling to and from the station would also be potentially lethal [41]. To date, every occupied space structure has been placed into a Low Earth Orbit (LEO), which is anywhere from 100 to 1000 km above the Earth’s surface and is considered safely removed from the highly charged particles of the Van Allen Belts [40]. For example, the ISS is in an equatorial orbit at an altitude of 400 km and circles the Earth every 90 min [42]. However, even if a space station were placed into the highest possible altitude of a LEO, the structure would still circle the Earth approximately every 96 min and thereby maintain disruptive sleeping patterns and free cycling for the occupants [16,38,39]. The option to totally internalize the environment and use technology to simulate a day/night cycle was considered but discarded as a viable solution for three significant reasons. First, if the habitat were technically internalized, the occupants would lose the warming sensation and the visual stimulation of the sun’s real rays. Second, the technological simulation would increase the draw on the station’s limited power supply, cease to operate in the event of a power failure, and add another on-board system that is costly and time-consuming to develop and maintain. Third, and most critically, the inhabitants would also lose an important source of Vitamin D. Exposure to natural sunlight produces Vitamin D in our bodies, which is important to the development of healthy bones and is even more important in space, where significant loss of bone mass and muscle atrophy is unavoidable in microgravity. Without exposure to natural sunlight, people in space would need to consume more fortified milk and yoghurt products, fatty fish and fish oils, all of which contain essential Vitamin D. This would result in a diet that is

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higher in fat, which would result in additional health concerns [43]. It was therefore concluded that for the health and safety of humans in a long duration space habitats, natural sunlight is essential and a LEO is best. 3.5.1. Station orbit There are two primary orbital paths around Earth: the equatorial orbit, occupied by most space vessels and all inhabited space stations, and the Polar Earth Orbit (PEO) used by some satellites. A spacecraft in a typical equatorial orbit circles the Earth approximately every 90 min, resulting in 45 min of constant sunlight before the craft is behind the Earth and without sunlight for the remaining 45 min of that orbit [42]. Any inclination of the orbit from the equator of less than roughly 65◦ would produce similarly rapid recurrences of light and darkness, whereas a PEO with an inclination of at least 65◦ can keep the station continually exposed to sunlight [40]. Therefore, the proposed orbital path for the space habitat is a PEO, to provide continuous sunlight enabling manipulation of the environment to achieve an adequate day/night cycle abetting the human circadian rhythm, and a 900 km altitude (LEO as mentioned earlier), rather than the typical 300–400 km altitudes, with an inclination of 65◦ or greater, so as to explore a more galactic setting for the research and study of human habitation aboard. 3.5.2. Dual rotation Given the need for a suitable day/night cycle and natural sunlight exposure for the occupants aboard, manipulation of the space station was investigated. Mechanical devices such as automated exterior shutters and solar deflectors were considered, but these were dismissed due to the inevitable mechanical breakdowns, maintenance problems and power consumption that are associated with moving parts. Another concept was to use the station’s thrusters to reciprocate the structure’s positioning to first face the sun, then face deep space and back again. The idea would provide a day/night cycle but would also consume considerable amounts of precious fuel. This concept, however, led to the notion of slowly rotating the structure about a secondary axis, the ‘B’ axis that is perpendicular to the ‘A’ axis about which the station’s artificial gravity is generated (Fig. 2).

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The secondary rotation about the ‘B’ axis that creates the occupants’ day/night cycle would be much slower than the 1 rpm of the gravitational rotation, and would indeed be so slow as to be unnoticeable to anyone aboard. The Earth’s day/night cycle is approximately 24 h, but the cycle aboard the station would be adjusted to suit the human circadian rhythm and optimize the adaptability and productivity of the occupants aboard [44]. Assuming that the work aboard (operations, maintenance, research) would have to be continuous, the crew would work in three 8-h shifts so at any given time one-third of the crew is working, another third is enjoying recreational time and the remaining third is sleeping. Assuming a 24-h awake/sleep period for all occupants, a typical “work day” begins with an 8-h work shift in which a person would experience sunlight for the first 4 h followed by darkness for the second half of the shift. The individual would work in an artificially illuminated space for 4 h until sunlight reappears, indicating the end of that person’s shift and the beginning of the succeeding work shift. The next 8 h would be the individual’s personal and recreational time in which they would again experience another 4 h of sunlight and 4 h of artificial illumination ending with the sunlight about to emerge as the individual draws all shading devices and turns off all lights in their private quarters in order to sleep the last 8 h of the “day” in darkness. Using an 8-h light/dark cycle would allow the station’s occupants to experience a diurnal rhythm that features only two sunrises and two sunsets per 16h period rather than the debilitating 10 or more that are experienced aboard present-day space habitats. Although this proposed 8-h light/dark cycle would need to be tested prior to implementation, it would appear to alleviate some of the difficulties that occupational shift-workers here on Earth have with being exposed to minimal daylight during the evening and “graveyard” shifts. Therefore, an 8-h day/night cycle was adopted for the proposed habitat to enable the station to rotate about its secondary “B” axis in such a way as to artificially create a suitable circadian rhythm for the crew aboard. To effectively accomplish the “sunrise” and “sunset” effect of the day/night cycle as the station revolves, most of the windows on the station are ori-

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ented in the same direction (Fig. 5). This allows the light that enters the station to move from a “sunrise” position through to a “sunset” position over the course of 4 h as the station rotates about the “B” axis. 3.6. Programming Effective spatial organization or programming of the different activities and functions aboard the space station is an important contributor to alleviating the psychological stressors of confinement and isolation. The living quarters are in the starboard portion of the primary torus, whereas the labs and workstations are located opposite, in the port section of the primary torus. Placing these functions opposite to one another would create a sense of “going to” work by making the occupants physically travel to some place other than where they spend their recreation or private time. The same concept applies for other areas aboard the station. For example, the cafeteria and lounge in the central hub would be opposite the recreational facilities located in the transverse decks; both are public social areas and one would have to “go to” or travel to them from the other location. The 1 km diameter of the torus represents little more than a 3 km walk to cover the full circumference of the station. Any commute to work would therefore cover no more than 1500 m and would hardly be excessive. The notion of “going somewhere” is important to the human psyche in space because it suggests to the occupants a scale and volume in their habitat that would mitigate feelings of confinement and isolation. Social, recreational and educational facilities such as the Observation Deck, the Zero Deck, the Entertainment area, and the Sport/Spa facilities and Library, engage and stimulate the crew on board, giving them various environmental activities to fend off monotony and boredom, as well as provide basic societal and community needs. In contrast, Supplies, the Animals/Agriculture area, Medical/ Dental/Psychiatry facilities, the Kitchen, the Command Bridge, Security, Maintenance and Engineering are communal and life support functions. 3.7. Spatial variation (Figs. 3–5) Spatial variation is another way to combat the stresses of space habitation by enhancing the station’s

Fig. 3. Privacy gradient of typical living quarters.

Fig. 4. Views within the central hub.

environmental stimulus. A range of different spatial experiences is therefore provided in the station’s design through various volumes and shapes of space, as well as different vistas and views. In the private quarters (Fig. 5), three room types are illustrated with different approaches to window locations and views, how one enters the space and the shape of the volume itself. This not only allows the occupants to enjoy some variety in their environment but also provides a more spacious volume that greatly reduces feelings of confinement and isolation. In the public area of the Central Hub, not only are the volumes, shape of space and visual stimuli at-

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Fig. 5. Views within the tori.

tended to but also the views become the primary focus. The openness from one deck level to another instils a feeling of vastness and intentionally creates certain vistas (Fig. 4). The issue of privacy is extremely important in confined environments. Research on Antarctic stations found that “60% of peoples’ waking time was spent alone” [45]. Conceptually, privacy is the ability to withdraw or separate oneself from others, and there needs to be spatial accommodations of different levels of interaction to allow selective control of access to one’s self or one’s group [46]. Even though humans are generally social creatures, there are aspects of our lives that we prefer to keep to ourselves or to a limited few. The private quarters therefore incorporate a privacy gradient (Fig. 3) in which the “street” is public and leads to a semi-public entry space, which in turn opens onto the semi-private living quarter in which the shared hygiene room is a completely private space when all access is locked. 3.8. Fenestration From a psychological perspective, windows aboard a habitable space vessel are essential. Windows allow people to view the Earth that floats below them, a sight that is passionately sought after by every astronaut. Mr. Wolff, Senior Vice-President of the architecture firm WAT&G, has stated that the primary reason people want to go into space is for the view [47]. Similarly, Dr. Kanas has commented that “Windows

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[in space] are a big thing and a favourite pastime is looking at the Earth, speculating about people down there—seeing no national barriers and the beauty of the environment—it means a lot and it keeps people rooted and connected” [48]. The provision of windows aboard this space station was therefore considered crucial, not only to allow the occupants to take in the pleasurable space-scapes but also to provide other forms of stimuli for the inhabitants through the natural sunlight’s physical and visual attributes. When sitting in the sun’s rays, one can feel its warmth as a tactile experience. When passing through an area of sunlight, an occupant feels the slight difference in air temperature as they enter the illuminated area, making them aware of their surroundings. Natural sunlight also produces shadows and enhances textures that together produce a more visually interesting environment. As the sunlight moves, not only does it animate the space but it also expresses the passage of time. Windows furthermore reduce feelings of confinement and isolation by enabling direct views of the space station itself. The habitat layout provides views of the overall vastness of the station that emphasize its scale and create visual stimulus for the occupants aboard. In addition, the asymmetry of the station’s form provides a variety of views of the overall structure from different locations within the habitat. The opportunities to explore the various vistas located throughout the habitat provide the occupants with a continuing stimulus and re-discovery of their environment, reinforcing a sense of spatial freedom rather than restriction. The primary arguments against windows aboard a space habitat are that they are extremely expensive [47] and jeopardize the hull’s structural integrity [49]. The option of using plasma screens in lieu of real windows was therefore considered, but ultimately discarded due to their inability to provide psychological relief. Holland reinforced the need for actual windows because the plasma screens would not satisfy the window criteria, which is the ability to genuinely look outside and observe distant features. True windows provide psychological relief from complete enclosure and provide a genuine visual horizon where one can relate to planets, stars and the Earth, whereby one has a stronger experience of being in space, which is a major motivating factor [30].

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Humans value the real thing, and a plasma screen presents a psychological disturbance between human observation and the exterior view. This psychological disturbance may not be an issue in the short term, but over an extended period it may develop into a serious psychological issue. Since the space station is intended for long duration habitation, the replacement of windows by plasma screens is not considered a viable solution for this project. Rather, advances in technology are relied on to render the provision of windows both structurally sound and financially feasible. The glass features filters to protect the inhabitants of the station from retinal burns or skin burns. As well, all windows except those used on the observation deck are equipped with shading devices that feature variable levels of shading for the comfort of the occupants. Lastly, water is sealed inside the glazing to enable much greater thicknesses of glazing than would be reasonably achievable using glass alone, to add to the window’s level of radiation shielding, and to help regulate the station’s temperature while remaining transparent [50]. 3.9. Structure The basic construction of the proposed space station is an aluminium structural skeleton that is covered with a double hull skin-like exterior. The structural framework consists of two components: a centre T-beam rib that defines the main circulation or “street” on the space station, and cantilevered deck beams which support the floor surfaces and extend out from the centre T-beam rib (Fig. 6). This dual component structure is repeated every 31 m to establish the circumference of the primary and secondary tori. Spanning the intervals between the dual component structures are framing members that provide surfaces for interior floor and wall assemblies. Aluminium was selected as the material for this skeleton for several reasons. To begin with, aluminium has long been the material of choice in the aerospace industry because of its light weight and moderate cost [51]. Also, since the artificial gravity generated aboard the space station creates a force that is only 56% that of Earth’s gravity, the forces on the structure would not be as much as here on Earth. Nonetheless, since this design is not expected to be technologically achievable for some time yet to come, it may well be that some

Fig. 6. Basic torus structure.

more suitable material will be discovered or invented between now and then. An additional consideration is the method by which the station is to be constructed: at present, a large space station would need to be transported into space in a multitude of space shuttle payloads and then assembled in orbit. However, it is likely that a more efficient construction system would have been developed by the time this design is built. The double hull skin-like exterior is not composed of aluminium but rather an assembly of different materials that are each applied for specific reasons. In terrestrial terms, the double hull is essentially an exterior wall construction with a cladding similar to that of a “rain screen” on Earth. The outer hull is a transparent Kevlar mesh through which one can see clearly and which has a reflective quality on the outer side that acts as a heat shield. This Kevlar cladding can withstand bullet-like projectiles and protect the inner hull from any meteorite strikes in a manner similar to NASA’s TransHab design [52]. The Kevlar mesh is applied to a transparent pliable backing material that is completely sealed to contain a low atmospheric pressure and retain any air that escapes from an inner hull breach.

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The inner hull is analogous to a terrestrial exterior wall application with some differences. It generally relies on the framing members for support and on insulation to maintain a comfortable interior temperature. The insulation could be a material such as Aerogel, which is 99.8% air, 39 times more thermally obstructive than fibreglass, and 1000 times less dense than glass [53]. This material or another more suitable one that has yet to be invented, would be contained and held in place by a layer of mesh. Inside the insulation is a 100 mm layer of polyethylene that protects the occupants from the radiation that abounds in outer space [54]. Moving inward, the habitat’s interior is composed of an airtight material that can contain the atmospheric pressure within the space station. This membrane would be similar to an EPDM roofing material and would be sealed to the windows to ensure total containment and no air leakage. Moving further inward lies a service space for pipes, conduit and wires, and beyond that is a quick release finished wall panel. Rapidly detecting hull breaches is critical to preserving the structural and environmental integrity of the space station. Therefore, between the interior and exterior hulls lies a cavity with a low air pressure and atmospheric sensors spaced every 3 m that are accessible from inside the vessel for maintenance and repair. If the inner hull were to rupture and cause an air leak, the sensors within the cavity indicate a sudden increase in atmospheric pressure in a specific area and a maintenance crew is precisely deployed to repair the damage. Once the inner airtight membrane is repaired, the precious escaped air is salvaged from the cavity between the two hulls. In the event of a rupture in the outer hull, the sensors would indicate a sudden decrease in atmospheric pressure in a specific area and again a maintenance crew is deployed to repair the rupture. Unfortunately, any air escaping through an outer hull breach would not be recoverable. Both hulls and the atmospheric sensors between them would need to be routinely tested to assure continued hull integrity. 3.10. Energy All the electrical power required aboard the station is intended to come from the sun, generated by fixed solar panels composed of specially manufactured silicon cells (Fig. 7). The solar energy is stored in

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Fig. 7. Solar panels illustrated in a preliminary sketch.

nickel–hydrogen battery cells ready for use as needed in the form of 160/120 V direct current that is distributed throughout the station [55]. Unlike other orbiting space stations that to date have not enjoyed a continual source of solar radiation due to their equatorial orbits, the proposed habitat has a continual light source to draw on, thanks to its polar orbit. 3.11. Safety and accessibility A 100 mm thickness of polyethylene is incorporated into the inner hull construction to protect the occupants from general atmospheric radiation. Upon the occurrence of a solar flare the occupants of the space station would wait out the radiation shower in the emergency life pods that double as storm shelters since they would feature more radiation shielding than the space station (Fig. 8). Additionally, the double hull construction of the station would minimize the escape of air into space upon the occurrence of an inner hull breach, and its early warning sensory system would rapidly indicate the location of any hull breach for damage control. To cope with a more catastrophic hull breach that presents immediate danger to the crew aboard, the tori also feature a compartmentalization of their 31 m sections so that a breached section could be quickly sealed off from the rest of the vessel. The “street” on the primary torus is continuous so as to prevent any dead ends that could trap a person during an emergency situation. With the primary torus being a complete circle, any section that is closed off

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A. Marie Seguin / Acta Astronautica 56 (2005) 980 – 995 Main Deck

Emergency Life Pod Access to Emergency Life Pods Torus section

0

15 m

Torus Main Deck Plan

Fig. 8. Emergency life pods.

for emergency reasons will not prevent others from carrying on with the emergency procedures or rescue operations. Also, emergency life pods are located directly below the Main Deck and are accessed through an escape hatch for ease of entry in the event of a devastating disaster aboard the space station that requires all hands to abandon ship. These pods are located every 15.5 m and each accommodates 12 passengers. During an unrecoverable emergency, these small craft would be ejected from the space station and directed back to Earth for a safe landing. Vertical lifts and stairs are located liberally throughout the habitat for ease of mobility from one deck level to another. On the primary torus, a circular stair is located within every 31 m section of the “street.” As well, vertical lifts are located within the Central Hub, each Transverse Deck, and half way along each arm of the primary torus. 3.12. Acoustics Unpredictable, irregular noise is generally more disturbing than predictable or constant noise. A constant, unbroken noise (especially if it is not loud) has been found to be not disturbing [56]. Unfortunately, as previously noted, the noises typically experienced by space travellers to date have been irregular, frequent, and loud. Therefore, to create a more desirable environment aboard the proposed space station, the noise produced by mechanical equipment is muffled and reduced to a level of 50–55 dB in public common areas and 35–40 dB in the private living quarters. In order to reach these decibel levels, acoustical materials are

applied to the mechanical equipment and ducting throughout the station. As well, appropriate insulation is installed in the floors and walls to resist sound transmissions throughout the habitat. Replacing the solid flat surfaces with pebbled or grated ones and using softer more acoustical surfaces like fabric helps to deflect or absorb ambient sounds. However, within a closed environmental system bacterial growth becomes an issue and can cause health concerns. Therefore, to achieve the desired acoustical levels without incorporating too many soft surfaces, the expertise of an acoustical engineer is needed to finalize the design. 3.13. Atmosphere It has been shown that the brain’s electrical activity rises with increased body heat, but slows to a level of drowsiness and restlessness at moderate and extreme heat levels respectively. Optimum human performance has been found to arise at a temperature of 18.3 ◦ C in a controlled environment, but only for a short period of time until the ideal temperature becomes whatever temperature is most comfortable for the individual in question [57]. Therefore, the temperature in the vessel’s “street” is set at 18 ◦ C to reinforce the idea of being “outdoors” and to stimulate brain activity and performance levels. The living quarter temperatures are adjustable between 20 ◦ C and 22 ◦ C to evoke the more cosy and relaxed feeling of one’s personal space. For the Zero and Observation Decks and other public areas, the temperatures would be set at 19 ◦ C to emphasize a public place and to provide some environmental stimulation that remains sufficiently subtle as to not become uncomfortable over time. The habitat is also fully pressurized to 1 atm (14.7 psi) with an Earth-like air mixture. The movement of air and its moisture level are also part of the atmosphere aboard the vessel and are manipulated to provide sensory variation within the habitat. The humidity level is set around 40% and can be varied to between 35% and 45% without concern [58]. However, humans are more sensitive to air movements. In the live/work areas where relaxation and concentration are of primary importance, an air volume or flow of 0.25 m3 /s is relatively unnoticeable and therefore not disruptive. In more public and stimulating areas like the “street” and the Zero and Observation Decks,

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the movement of air at 0.25–0.51 m3 /s is noticeable but pleasant, making the individual aware of his environment without annoyance [59]. 3.14. Social context One of the best ways to relieve boredom and monotony is through interaction with others. However, this can become difficult when there are a limited number of individuals in a group. With small numbers, a once interesting and stimulating social group can quickly become tedious and annoying. The proposed space station accommodates 300–500 people, allowing dozens of people to interact and socialize at any given time. Each crewmember encounters various crewmembers in a variety of different circumstances and situations, creating a very dynamic, stimulating, and engaging social context. Confirmed by Holland, this social complexity tends to counteract the social tedium encountered on so many space missions to date [30].

4. Conclusion Each of us is the product of millions of years of evolution in the terrestrial environment, so it should be no surprise that a mere 40 years of space exploration by a few specialized individuals have proven insufficient for the human species to adapt to the dramatically different environment outside Earth’s atmosphere. Rapidly transplanting humans from their naturally stimulating, expansive and variable earthly setting into a confined, isolated, monotonous and mechanical spacecraft almost inevitably results in psychological disruption and dysfunction. This proposed new approach to extraterrestrial architecture will sustain human life in space more effectively than present day space stations because it mitigates the common negative psychological effects of spaceflight by providing a terrestrial quality and a level of normalcy that are desired by humans who are in space for prolonged periods of time. By providing earthly associations, this new approach eases the difficulties of space adaptation and effectively bridges the gap between the terrestrial and extraterrestrial ways of life, producing a human habitat that can be enjoyed rather than merely endured. This design seeks an ap-

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propriate balance between the earthly and cosmic conditions in order to ease the transition from human to spaceman, and the result can be expected to far better support the mission and augment the success of longterm human ventures into space. The inescapable conclusion to be drawn from the increasingly vital relationship between the human experience in space and the extraterrestrial habitat design is as follows: the crucial next step in long-term space human habitation is to adapt the habitat to the needs of the occupant rather than force the occupant to endure a needlessly unnatural environment. Notwithstanding the advances that are reported and advocated in this paper, further investigation is recommended in order to optimize the design of any future extraterrestrial habitat. Among the topics that would benefit from additional research are: • the ideal length and frequency of the light/dark cycle; • the technological feasibility of dual rotation of the space station; • an empirically determined comfort zone for Gforces and the Coriolis effect; and • the design of large spans of structurally sound and financially viable fenestration.

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