IV. Habitability

Habitability refers to making life onboard Æther as acceptable to the inhabitants as economically possible.  With permanent residency on Æther being considered, it is not prudent to always opt for low cost and ignore habitability.  Permanent residents of space will not accept the relatively primitive conditions that exist today onboard space flights.  In Æther, the emphasis must be on providing an environment that a person would be happy, healthy, and successful in family life, work, and community relationships.  Negative emotions such as anger, fear, envy, loneliness, or greed must be prevented as much as possible through design.  The three main annoyances in current spacecraft that detract from habitability are low levels of environmental comfort, personal inconveniences, and a lack of personal control over their environments [ref 13].


IV.A Basic Habitability Aspects

            Basic habitability aspects are as follows: climate, illumination, colors and surfaces, décor, vibration, odor, noise, pests, interior space/layout, hygiene, and food and drink [ref 1].  Although some of these components alone may seem insignificant, when combined they determine the quality of life onboard Æther and ultimately will be a key factor in whether or not colonization of space is successful.


IV.A.1 Climate

Maintaining a comfortable “shirt-sleeve” environment is key to having a vibrant, productive colony.  Studies have demonstrated a reduction in cognitive and psychomotor performance at and above a temperature of 302 K (~30˚ C, ~85˚ F) [ref 14]. Performance also suffers if the temperature is below 291 K and the decrease in performance is proportional to the length of exposure.  Therefore, the CELSS must provide an environment between 291-300 K and 25 – 70% relative humidity.


IV.A.2 Illumination

Illumination is vital for visibility within Æther.  NASA standards advise that “bright and uniform” wide-spectrum light should be employed in work areas; nighttime and social activities could just utilize warm white light, this would also serve to help the average human’s association of “warm” light with such activities [ref 13, 14].  Natural lighting via the windows could serve the purpose of wide spectrum light.  Windows and/or viewing panels are important for satisfying curiosity and orienting the colonists to their external environments and should be integrated into the exterior design of Æther.  However, sharp differences in lighting between adjacent areas should be avoided to reduce the difficulty of adjusting.  Special care must also be taken when viewing objects through a window, as bright objects and glares are detrimental to eyesight.  Simulating 14-hour days and 10-hour nights would also be required in a colony that receives 24-hour sunlight.


IV.A.3 Colors and Surfaces

Colors and surfaces provide a sense of aesthetics but also can be very useful in navigation throughout the colony. Colors are especially important in micro-gravity areas where directions of “up” and “down” are not absolute. Painting the “ceiling” a different color from the “floor” could help workers easily orient themselves in micro-gravity work areas.


IV.A.4 Décor

Décor such as art helps people adapt to monotonous environments, and pictures of earth landscapes could educate children born in space about earth.  Flexible décor such as movable partitions, removable wall covers, etc. give colonists a sense of personal control as well as adding variety.  A resident artist program will also be established to ensure the diffusion and advancement of all visual arts.


IV.A.5 Vibration

Elimination of vibration is important for health and comfort of the colonists.   Ways that vibration can be transmitted to the body is through the hands (known as hand-arm vibration or HAV) and through the seat or feet (known as whole body vibration or WBV).  Exposure to HAV can cause negative health effects that are collectively called hand-arm vibration syndrome.  Health effects include vibration white finger, which is the lack blood supply to the fingers and can cause uncomfortable and sometimes painful spasms [ref 15]. Various frequencies of WBV have different effects on health, back pain occurs at 4-12 Hz; WBV of 4-5 Hz causes digestive diseases; and frequencies below 20 Hz instigate cardiovascular disorders [ref 16].  Discomfort from vibrations is most common in the form of kinetosis (motion sickness), which is at its worst with frequencies of 0.125-0.25 Hz.  Vibration measurement systems consisting of a transducer to sense the vibration; an amplifying device; a frequency weighing filter which accounts for variations in human response to different frequencies; a data recorder; and a signal analyzer, should prove to be of use in determining what preventative measures are needed.  Such measures include limiting the time spent by workers in a vibrating environment, mechanically isolating the source of vibration, maintaining machinery to minimize vibrations, and installing vibration-damping insulation [ref 15, 16].


IV.A.6 Odor

Odors can accumulate rapidly when air is recycled, fortunately people adapt to increasing concentrations of odors quite well. However, toxic substances, whether pleasant smelling or not, must be kept below unacceptable levels.  Also, obnoxious odors must be controlled to minimize distraction and dissatisfaction.  Most odors originate from hygiene and bodily functions; to counter hygienic odors colonists must be able to wash themselves at least once a week and change into fresh cloths at least twice a week.  Electrostatic ionization, dry scrubbing, chemical bed filtration, and ultraviolet radiation are all methods that can reduce odor onboard Æther.  Chemical bed filtration removes solid pollutants from the air, electrostatic ionization removes large particles, dry scrubbing reacts unwanted gasses or vapors with a sorbent bed, and UV radiation destroys germs that produce odors [ref 13].


IV.A.7 Noise

Sources of ambient noise onboard Æther will be pumps, fans, transportation infrastructure and other equipment.  This ambient noise could potentially become an annoyance and interfere with speech and sleep if not properly controlled.  Ultimately, noise can cause aggressive behavior. Several methods can achieve the design goal of less than 35 dB for residential areas of Æther, and a higher limit of 55 dB for work areas.  Soundproofing will be especially important in high-density apartments, where a sense of privacy is needed.  Soundproofing methods include: increasing mass, which adds inertia to walls and prevents excitation; decoupling contiguous building elements, thereby prevents transmission of sound; inserting absorbent material converts and dissipates acoustic energy; using sealant, thus thwarting the passage of sound through gaps and cracks; and including viscoelastic materials to help deaden sound [ref 17].  Where unwanted sound is continuous or highly repetitious, active sound cancellation may be considered.


IV.A.8 Pests

            We as human beings despise pests for many good reasons; pests commonly are the carriers of deadly disease, cause great discomfort, and are also associated with low standards of living.  Common pests of home, people, and pets found on earth include ants, bed bugs, bees and wasps, recluse spiders, carpenter bees, carpet beetles, cliff swallows, clothes moths, cockroaches, conenose bugs, delusory parasitoids, fleas, head lice, hobo spiders, horsehair worms, house flies, house mice, mosquitoes, pantry pests, silverfish and firebrats, stable flies, termites, ticks, windscorpions, and wood-boring beetles [ref 36].

Immigrants will be screened for pests, and active control will be undertaken.  In spite of this, the possibility of pests and/or their eggs reaching Æther still exists. Since the most common form of pest control, pesticides, would be hazardous to use onboard Æther, other forms of pest control, such as baits and traps should be considered.  They are also considered to be more effective in controlling pests since the prolonged use of pesticides leads to an increased frequency in pest population of pesticide-resistant members [ref 33]. Forms of natural control include using parasitoids, predators, pathogens, and weed feeders to destroy pests [ref 35].

Parasitoids develop inside of and eventually kill their hosts, and they are dissimilar in their choice of hosts; thus different species of parasitoids must be imported to combat different species of pests. However, the concern that some parasitoids may be considered pests themselves limits the effectiveness of parasitoid pest-control.  Despite that concern, many species of parasitoids would not be considered pests and could potentially be used as pest control, such as wasps, of the Anaphes flavipes, Bathyplectes anurus and B. curculionis, Catolaccus grandis, Cotesia glomerata, Diadegma insulare, Encarsia formosa, Encarsia inaron, Eretmocerus californicus, Eriborus terebrans, Lysiphlebus testaceipes, Metaphycus alberti, Muscidifurax raptor, Nealiolus curculionis, Peristenus digoneutis, Pholetesor ornigis, Trichogramma ostriniae, and Trissolcus basalis species; and flies of the Pseudacteon spp. and Trichopoda pennipes species [ref 35].  Most of the parasitoids would be used in the agriculture areas, where they would be of great help in reducing the population of crop pests such as the cornborer, the cabbageworm, and the boll weevil. Although the environment inside the agriculture sections consists mainly of plant growing machinery and hydroponics equipment and will naturally not support many pests, the probability that pests will infect communal growing areas which do not use hydroponics is high, since many pests, their eggs, and their offspring are small and easily hidden by natural habitat.

Predators consume their nonspecific prey and thus can be used to control a wide variety of pests, mostly crop pests.  They include beetles and lady beetles of the Chilocorus kuwanae, Chilocorus stigma, Coccinella septempunctata, Coleomegilla maculata, Cryptolaemus montrouzieri, Harmonia axyridis, Hippodamia convergens, Pseudoscymnus tsugae, Rodolia cardinalis, Stethorus punctum, Lebia grandis, and Aleochara bilineatis species; bugs of the Campylomma verbasci, Deraeocoris nebulosus, Geocoris spp., Orius spp., and Podisus maculiventris species; lacewings of the Chrysoperla carnea/Chrysoperla rufilabris and Hemerobius spp. species; midges of the Aphidoletes aphidimyza species; mites of the Galendromus  occidentalis, Galendromus  pyri, Neoseiulus  fallacies, Zetzellia mali, Euseius tularensis, and Phytoseiulus persimilis species; and harvestmen of the Phalangium opilio species [ref 35]. While predators may play a limited role in the containment of pests, they would serve as a major educational and physical link back to earth, and children born in Æther would still be able to identify themselves with their ancestors even though they live in space.

Beneficial pathogens and antagonists aid humans by infecting and suppressing harmful pests [ref 35].  The term pathogen usually refers to a bacteria, virus, or fungi that infects harmful insects or mites, while the term antagonist refers to a microorganism that is helpful in the control of microorganisms that cause food spoilage and plant disease [ref 35].  Pathogens, like parasitoids, are species specific in their selection of hosts, but both pathogens and antagonists can be inserted into solutions that can be sprayed [ref 35].  Antagonists will probably be used the most since they, when incorporated into waxes and other coatings, can effectively inhibit food spoilage.  Pathogens to be used onboard Æther would include viruses, bacteria, fungi, nematodes, protozoa, and algae, while antagonists to be used would include the species of Ampelomyces quisqualis, Phanerochaete gigantea, Pseudomonas syringae, and Trichoderma spp. [ref 35].

Weeds that reached Æther would quickly propagate and cover much of the arable landscape inside, since there would be little to no preexisting methods to control those weeds.  To offset this effect, natural enemies of weeds should be imported to Æther. Weed feeders include moths, fungi, weevils, beetles, and flies.  However, their effectiveness may be limited by parasitoids and predators, which may also prey on weed feeders.


IV.A.9 Interior Space/Layout

            Space for colonists must be adequate for their needs yet not so much as to be redundant and unnecessary.  Space for CELSS machinery, recreational and social functions, living habitats, communications infrastructure, transportation, agriculture, storage, and businesses must be provided for [ref 34]. While some space needs are unique, many based on communal activities, such as assembly space, share common elements with other needs.  Thus, a space designed for assembly could be simultaneously used for a mosque, a church, and a community hall.  Hopefully, instead of having tensions arise from shared use, it is hoped that the different elements of Æther will be bonded closer together because of this sharing. Recreational areas are needed for housing the recreational activities that will be available to the colonists, their importance is discussed later.  Open spaces with grass, trees, and possibly some recreational areas, on the other hand, if placed next to high-density regions provide a release from the pressure of other people, and also diminish the sense of living in a manmade object [ref 34].  They can alleviate the sense of artificiality that arises when people are placed into created environments. Introduction of pets that colonists can grow or take care of would also help create a sense of control as well as maintaining a visible connection between the colonists and earth.  The design and construction of habitats should closely adhere to privacy and personal aesthetics goals set forth by the individuals who will eventually reside in those habitats.  Thus, it must follow that a very flexible but fast method of construction must be employed, which could give rise to many different types of dwellings [ref 34].  Such a system could be achieved by using modular parts, which can provide a wide variety of combinations.  The structure would be made out of metal beam components, while panels fashioned out of lunar slag and with decorative coverings would provide soundproofing and fire deterrence.

            The space needs inside the torus can be summarized in the following table.


Area per person (m2)

Total (m2)




Agriculture and Food Processing












While the total figure of 1.37x107 m2 clearly exceeds the total area available on the primary floor of the torus, it should be noted that the torus also contains a lower level that would house most of the agriculture and food processing space and that most buildings in Æther will be multi-story, thus creating out of a piece of land two, three, or four times the original amount of space.


IV.A.10 Hygiene

            Hygiene water has the potential to place a high strain on the CELSS, particularly the water management subsystem.  Hopefully the majority of colonists will be able to maintain an acceptable level of hygiene while not using an excessive amount of water.  Toilets in the residential areas will be similar to those on earth for maximum ease and comfort, but those in the microgravity environment of the work areas will have to be highly reliable and not suffer the mechanical difficulties of the integrated fecal/urine collector onboard the space shuttle.  Showers should be efficient as possible, thus the use of graywater heat recovery systems is warranted.  In such a system, the exiting wastewater transfers some of its heat to the incoming cold water, thus reducing the energy load on the water heater.  Graywater heat recovery systems could also be implemented in other areas where hot water is needed.


IV.A.1 Food

            Food is an essential part of daily living, as it not only fulfills physical needs but also psychological and social needs. Shared meals help create unity between colonists and food serves as a form of recreation in boring environments. For example, good food is a major motivation for sailors in submarines and remote Antarctic research bases [ref 13]. Thus it is important for food aboard Æther to not only be nutritious but also to be delicious.  However, due to the restrictions of the CELSS, most meals will be heavy on cereals and vegetables.  Further discussion of this issue can be found in the CELSS section.  Consuming alcoholic beverages are a common recreational pastime in the US, it also causes many problems if the consumer becomes inebriated.  However, it also serves as a powerful motivator for some people.  The allowance of alcohol on Æther will have to be seriously considered, and although current NASA policies no alcohol to be available during space missions, to some careful consumption of alcohol is seen as a valid way of releasing stress [ref 13].


IV.B Long Term Habitability Aspects

            Long-term habitability aspects are as follows: crew composition, health care, communication, privacy, and entertainment [ref 1].  They become important when considering extended periods of residency.


IV.B.1 Crew Composition

            Crew composition will be important in long-term missions because colonists must be able to work together.  However, debate over whether colonists should be selected on a “first come, first serve” basis or on a merit basis arose.  While the selection of colonists should not be exclusive, unwanted elements of society such as criminals should not be allowed onto Æther.  A combination of these two selection processes was finally chosen.  The initial wave of “pioneers” would consist of merit based selected colonists who would essentially test Æther’s CELSS reliability, then a “first come, first serve” selection process would be initiated for the “settlers,” who would take the remaining open slots in Æther.  Companies could also apply for a group permit, but the available slots for companies would be limited so that the opportunity to live in space would be presented to individuals.  Equal representations of both sexes would be desirable, as well as representatives from most major cultures.  The screening process for the pioneers will not be as selective as those conducted for astronauts, but those who go will first most likely be above average in cognitive and spatial aptitude, be willing to take risks, be cooperative, and be emotionally mature and stable.  The pioneer population will be around 5,000-10,000 and will live in Æther for 1 year before the settler application process begins.


IV.B.2 Health Care

            Maintaining distinguished health care facilities will be important for attracting permanent residents to Æther.  The ideal health care system would provide the best health care available while respecting the rights of the physician and the patient [ref 32].  A sufficient number of physicians is needed for the proper health care of the colonists, and some specialty services would also be provided, but for some extreme cases that would not be able to survive the journey back to earth, transportation of specialized doctors from earth would have to be arranged.  Hospitals and emergency vehicles would be provided for, and the goal of one doctor per 400 persons should be maintained to provide quality care.


IV.B.3 Communication

            Communication can be divided into communication within Æther, communication between Æther and other space habitats or earth. Communication serves both task and socio-emotional functions [ref 14].  Task communication involves the organization and coordination of work, while socio-emotional communication is more of a personal nature.  Communication within Æther will mostly be in the form of verbal and nonverbal communication.  Ambient noise from machinery and its implications on communication has already been discussed prior; however, decreased atmospheric pressure will also impair sound transmission, and colonists would be required to talk louder than normal. For obvious reasons, all colonists must be fluent in a common tongue, this requirement is especially important in demanding situations, when a human’s ability to process complex information is diminished.  Using current standards, the official language onboard Æther would be English. However, even when two or more people are communicating in the same language, there exists the problem of regional dialects and accents.  Obstacles to effective communication would include subtleties of intonation, inflection, context, meaning, and interpretation [ref 14].  However, these are mostly unavoidable obstacles, as the colonists will come from many cultures and regions.  Hopefully, the situation will rectify itself as the colonists interact with each other and develop a new dialect of English.  Nonverbal communication has three modes: paralinguistic (amplitude, rate, and tenor of speech), kinesic (facial expressions and gestures), and proxemic (distancing or placement).

Nonverbal miscommunication will occur in the micro-gravity regions of Æther, where proxemic and kinesic modes of nonverbal communication will be hindered by the puffiness of the face and difficulties in anchoring oneself.  Again, cultural and regional difficulties will cause proxemic miscommunication, since different cultures consider different distances as too close or too distant [ref 14].

Communication between Æther and other space habitats or earth will necessitate the use of an electronic medium; thus, satisfactory bandwidth will need to be achieved between these three points.  This communication will be in the form of different types of media such as full motion video, audio, written messages, and data.  This type of communication will be of utmost importance to colonists who have left family or friends on earth to live in space.  Generally, if the dialogue is between family members, full motion video is the preferred means of communication as it contains the most modes of communication (kinesic, paralinguistic, and linguistic).  However, communication through normally instantaneous means is made awkward because of the time necessitated for the electromagnetic wave to traverse the distance in between earth and Æther.  The time lag that is introduced would be noticeable, but not overwhelming.  Given the fact that real-time full motion video is bandwidth-consuming, adequate bandwidth must be allocated to facilitate the massive demand that would be placed on this service inside Æther and between Æther and earth. 

Audio communication is next in being most information-rich as it contains both paralinguistic and linguistic modes [ref 14]. Many technical challenges are present with a fully duplex audio communication system in which both users can speak at will [ref 14].  Attaining high quality in audio is also difficult if not using free arrangements (where individuals are attached to microphones and earphones), but is essential for frequent usage and satisfaction of the system.  Audio communication has the advantage that most users are familiar with telephonic devices on earth and that it offers more privacy over video communication.  If high audio quality is attained, then this means of communications will account for most communication inside of Æther.  Written messages are only able to transmit text and pictures and are limited to the linguistic mode of communication.  Most written messages in Æther will assume the form of computerized exchanges, thus an infrastructure for handling this medium will need to exist.

In gaining widespread acceptance of the video, audio, and written lines of communication onboard Æther, the designer must fully understand the colonists’ needs, the benefits of the designed system must be made clear to the colonists, and the colonists need to be properly trained in the operation of the different systems.  Integrating the opinions of pioneers into the design process is helpful for designers trying to understand the attitudes and needs of people living in space [ref 14]. 


IV.B.4 Privacy

            Privacy is arguable one of the most difficult and perplexing parts of habitability.  Not only do individuals have varying levels of privacy, the notion of acceptable privacy differs from culture to culture.  Given the context of an international population living onboard Æther, designing for privacy is a complex issue.  The term “privacy” refers to a plethora of meanings, such as the “need for adequate space; visual, physical, or psychological separation; low population density; control over space, possessions, or information; freedom of activity; and many other concepts” [ref 14].  One definite way to ease the sense of little privacy is to ensure that each colonist receives an ample amount of space that he or she can call his or her own.  Another is to allow the colonists to control information about themselves, thus there should not exist detailed dossier of answered questionnaires and on each and every colonist. A sense of privacy is further enhanced if homes and apartments are sufficiently acoustically insulated so that conversations can be kept private and annoying ambient noise kept to a minimum. Crowding will become less of a problem if neighbors become acquainted and become friends instead of merely being strangers who live in a close proximity.


IV.B.5 Entertainment

Off-duty functions are essential to balancing the colonists’ work.  Most recreational activities available to humans on earth must also be available to colonists.  Humans have a tendency to choose passive entertainment over active entertainment [ref 14].  Passive entertainment is usually in the form of mass media such as magazines, television shows, movies, etc. and can easily be provided for in Æther.  However, active entertainment is also an important means of relaxation and the needs of the colonists in this aspect should be addressed.

Some types of entertainment would not be available to colonists because of several reasons.  Smoking will be strictly forbidden as it would place too great of a strain on the CELSS air management subsystem.  Other recreational drugs in the form of sedatives, stimulants, hallucinogens, and painkillers have shown to have no positive uses outside of the medicinal world and will not be available for recreational purposes due to the negative effects brought about by long-term use.  One exception would be caffeine, and others could probably be found given more research.

Not only must conventional active and passive entertainment be provided, but other, novel entertainment should also be available to enhance the appeal of living in Æther.  Given the exotic locale of Æther, such entertainment will be plentiful. Such entertainment could be earth-based activities that have been transplanted into a zero-g environment such as swimming, handball, and tag, or new activities that the colonists invent.


IV.B.6 Education

            Providing inspirational education is key to combating boredom and creating a sense of personal growth.  The learning process is continual and should be aided and encouraged by both school and community.  Due to the size of Æther, schools of decent size would be able to be constructed for pre-primary through post-tertiary education.  In the primary, secondary, and tertiary schools there should exist a plethora of classes, but not at the expense of quality. Core classes in the basic sciences, mathematics, languages, social sciences, and fine arts should be complemented and applied to daily life in other classes.  Being able to choose classes would alleviate the deprivation of control in an artificial environment such as Æther.  The structure of the education system in Æther should be left for the colonists to decide, but it should be noted that constant interaction between different ages is beneficial to the unity and development of the community. Educational opportunities for older generations should be made available in either distance learning or “night classes” offered at tertiary educational establishments.

            Schools are not the only places where education occurs, cultural establishments such as the library, museums, and research centers also offer excellent educational opportunities.  The library could serve as a book repository for school classes while also serving the general public.


IV.B.7 Interior Transportation

            Life onboard Æther will require efficient means of transporting colonists from any given place inside Æther to another place. Public transportation would be the most effective way of meeting this need, since it can transport people using a minimum of infrastructure and energy.  Design goals for public transportation should include low jerk rates (1-2 m/s3), low accelerations and decelerations (1.5 m/s2), insignificant or no fares, fast transit speeds, pleasant accommodations, high reliability, little to no noise, and extreme safety [ref 42]. Transit speeds should be fast so as to not cause inconvenience, but should not be so fast as to cause massive Coriolis forces.  Thus speeds tangentially in opposition to or in conjunction with the rotation of the colony should cause no more than a 0.1g deviation, thus the approximate maximum speed should be 7 m/s (26 km/h).  Monorails will be used to provide Ætherians with fast public transportation.  Monorails trains are either suspended or supported by a single rail.  Wheels that make contact with the rail supply the forward motion.  Because of their simplicity, monorails operate quietly, efficiently, and reliably. The monorail line would be constructed so that passengers will have a good view of the colony interior, but will not be so high as to cause large Coriolis forces when the passengers embark and disembark from the monorail.  Bike and walking paths would also be built to facilitate easy access. Transportation from the torus to the spheres would be handled by elevators inside the connecting spokes, which would also move slowly to prevent uncomfortable Coriolis forces.



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