What are Mars Analogue Missions Really Studying?

While various parties argue back and forth about whether humanity has progressed far enough technologically to colonize Mars, technology alone will not determine the success of such a venture. Interpersonal relationships and how the first colonists are able to work together to augment their strengths and mitigate their weaknesses will also be an incredibly important element in producing success. With this in mind NASA and other space-based organizations have undertaken occasional training experiments or analogue missions in an attempt to simulate a mission to Mars. These missions typically take place in specific locations in Hawaii or Antarctica, which are suitable for simulating Martian environment as far as Earth can simulate Mars; however, do these analogue missions have the appropriate goals and tasks for the participating individuals to properly simulate a Martian colonization party?

The major goal of these simulation experiments is to access how different individuals interact with each other over a fixed continuous time period in a confined space, simulating conditions in both travel to Mars and after landing, in effort to understand and predict potential positive and negative behavior among the colonizing party. However, the environment these individuals are commonly thrust into is not similar to that which will be faced by the initial colonists. While the inside habitat-outside habitat transition is properly simulated through the use of space suits, the activities of the participants within the habitat are more focused on specific scientific studies, not on building and developing the operational structure of the shelter. In short these experiments focus too much on simulating a developed Martian habitat versus a developing one.

For example one of the first major issues for a Martian colonization mission is that there is little to no food growth on site. The first colonists will bring a significant amount of food with them when first traveling to Mars, but almost every expert is in agreement that the development of some means to grow sufficient amounts of food on Mars will have to occur soon after arrival for it is too costly to continue to re-supply from Earth. Unfortunately these simulations experiments do not appear to be modeling this critical element for Mars colonization. This lack of planning is a missed opportunity because there are questions to what is the most effective way to grow food on Mars and various simulations starting from scratch could produce important information to determining which method would be the most successful in a real colonization mission. Every scientist and engineer knows that laboratory simulations/conclusions and in-field simulation/conclusions can differ radically.

One of the sub-questions on this issue is what type of food growth system would be optimal for Martian colonization both in the interim and for expansion. Various options, such as hydroponics, aquaponics, aeroponics, cultivating Martian soil, etc. exist and analogue missions would be an effective means to produce higher quality costs, effort and efficiency estimates of these system, both alone and in cooperation with each other, apart from ISS analysis and laboratory hypotheses. Aeroponics is NASA’s leader in the “clubhouse”, but would it work well as the initial on-site food provider for the first Martian colony?

Furthermore due to the significant reduction in gravity on Mars, colonists will have to engage in a rigorous exercise program to reduce the potency of negative physiological effects associated with the loss of this gravity. Simulating the necessary exercise in these analogue missions cannot help study how it influences health on Mars due to the lack of similar gravity, but it can help study how such levels of vigorous exercise would influence energy levels and food consumption along with interpersonal relationships. Unfortunately this potentially valuable information is not acquired in these simulations because the participants are not instructed to exercise in such a way.

Another important connective element that is lacking in these simulations, due in large part to the lack of these above elements, is the changes in stress that would accompany this behavior and these goals. While it is not ethical to emulate the life threatening conditions that failure would bring, general failure to complete necessary tasks would create tension and stress through challenges to the pride of the individuals involved, thus would better emulate real Martian colonization conditions. In these moments of stress, potential problems within the group dynamics can be identified that would not exist when stress levels were not increased leading to a better understanding of how to manage failures in the real colonizing party.

In the end analogue missions are important for various reasons and while human factor elements are certainly important to study and general simulation research strategies have their place, there needs to be more simulations that mimic what colonists will experience when first landing on Mars to better create a methodology regarding how to maximize success for the Martian colonization mission. Overall without expanding the scope of analogue missions to reflect the realities of Martian colonization, one wonders what the point of conducting these missions in the first place actually is, for they are certainly not preparing colonists for the most important part of the colonization, establishing the environment and behaviors to increase the probability of long-term survival.

Torpor in Space Travel

With existing tested technology the fastest transit time between Earth and Mars is during the perihelion (although Mars has only come within 34.8 million miles in 2003 versus the 33.9 million of the actual perihelion) resulting in a minimum transit estimate of approximately 180 days. Some believe that six months of monotonous space travel would be a significant psychological detriment on the future colonists, thus they recommend investigating a strategy of inducing torpor initiated through a therapeutic hypothermia methodology. Therapeutic hypothermia involves lowering an individual’s body temperature and is commonly reserved for medical emergencies involving cardiac arrest and various embolisms like strokes. It is thought that the decrease in temperature reduces biological metabolism, which reduces tissue damage born from oxidation and excess neuronal excitation triggered by a lack of regulated blood flow. Note that torpor is a state of decreased physiological activity through a reduced body temperature reaching a lower limit of survivable metabolism. Due to these changes torpor is commonly viewed as a state of consciousness distinct from wakefulness, sleep or coma.

The chief method to induce therapeutic hypothermia is a controlled reduction of core temperature through one of three possible methods: 1) invasive cooling usually involving an IV of cooled fluids; 2) conductive cooling where the body is placed in contact with cold compresses, typically cold gel pads and/or wet blankets; 3) convective cooling where specific gases evaporate and pass into the nasal and oral cavity leading to a reduction in body temperature.

Of the three conductive cooling is typically the most widely utilized because of its effectiveness and simplicity. Some researchers have explored new and more direct chemical methods to develop a hibernation state like activating adenosine receptors or using hydrogen sulfide to reduce cellular demand for oxygen.1 Others have thought to induce hibernation through synaptic manipulation, but that method is probably best avoided due to brain plasticity issues, which could result in temporary or permanent brain damage.

While the above methods are viable for inducing therapeutic hypothermia, a significant concern for a “hibernated” space travel strategy is that cooling/cryogenic strategies are in their infancy, thus most therapeutic hypothermia states rarely exceed 24-hrs and the longest is only about 14-days, a long cry from the 180-days of a trip to Mars. In addition to improving cooling methodology, temperature monitoring needs to be improved to incorporate a better realization of core temperature versus localized temperatures from specific measurement points (bladder, rectal, tympanic or esophageal). In general practice these specific measurement points tend to correlate with core temperature, but long-term hypothermia inducement will more than likely require more universal tracking of acute internal temperature changes. In addition to lowering the core body temperature one must neutralize shivering otherwise metabolic rates will not decrease sufficiently to realize the associated therapeutic benefits. Currently shivering is commonly controlled through the application of desflurane, pethidine, and/or meperidine.2

The most obvious non-psychological benefit of placing a colonization crew in torpor is a significant reduction in food/consumables for transit and the potential reduction in overall consumables. The reason that the overall reduction may only be a possibility is determined by whether or not the non-consumption during transit will transfer to “on Mars” consumption. For example suppose 1 ton of food (not mission specific just a number for example purposes) is loaded for a standard non-torpor mission and among the four colonists a total of 4 pounds is consumed daily. Over the course of the trip approximately 760 pounds of food will be consumed leaving 1,240 pounds of food for consumption on Mars. In a torpor mission two strategies are available: 1) only 1,240 pounds of food will be loaded saving 760 pounds for something else or just straight cost savings; 2) 1 ton of food is loaded with no cost savings, but an additional 760 pounds of food will be available for consumption on Mars.

Secondary benefits come from the possible reduction in the required pressurized volume in the living quarters and the elimination of ancillary crew accommodations, which could reduce the size of the transport craft reducing the total cost of the mission or increase the ability to add subsystem redundancy and/or more radiation shielding at similar costs. Basically the chief non-psychological benefit for a torpor mission is a greater flexibility in distributing what types of materials are loaded for a Mars mission and the final mission cost.

While torpor proponents would suggest that there are a few bugs left to work out, but prospects for such a strategy appear viable, in actuality there remain two significant problems that must be overcome before a torpor strategy can be viewed as viable. The first problem, the most pressing, is muscular atrophy born from general space travel and the second problem is overall safety. The principle responsibility of skeletal muscle is to govern movement of all voluntary muscle, including the maintenance of posture. Due to human evolution on Earth skeletal muscle has to move parts of the body against gravity, thus there is a strong relationship between the size and metabolism of skeletal muscle and the gravitational force of the existing environment.

Skeletal muscle is comprised of bundles of muscle fibers, which are large cells formed through the fusion of many individual cells during development. Most skeletal muscles consist of myfibrils, which are cylindrical bundles of either thicker myosin filaments or thinner actin filaments, and form contractile elements (sarcomeres). Sarcomeres are separated into Z discs (the ends) along with A and I bands where A bands are largely comprised of myosin and I bands are largely comprised of actin. Some have additionally defined a buffer zone of sorts (H zone).
The general methodology for muscle contraction is the sliding filament model.

Muscle fibers generate active and passive mechanical forces to overcome gravity to ensure proper posture, movement and biological function. Active muscle tension is derived from muscle contractions leading to shortening of myofiber’s sarcomeres whereas passive tension occurs through sarcomere stretching reducing their level of overlap.3-5 It appears that slow twitch muscle fibers are more susceptible to the change in gravitational force versus fast twitch muscle fibers.6,7 This difference in degradation can be troublesome because not only is slow twitch muscle more associated with posture, but is also associated with muscular endurance. In addition to muscle atrophy there is a serious drop-off (>50%) in protein synthesis rates and a significant loss of calcium balance.8-10 Whether or not this loss of calcium is due to actual direct losses or indirect absorption losses (i.e. a lack of Vitamin D) is unknown.

The change in protein synthesis rate is further compromised by activation of protein degradation rates.11 One of the major pathways responsible for atrophy is the ATP-dependent ubiquitin/proteasome pathway with the most important feature being E3 ubiquitin ligase due to its specificity in targeting certain proteins for elimination.12

Torpor proponents believe that the negative influence of atrophy, which will be much worse for individuals in torpor because of the lack of ability to exercise, can be neutralized through the use of neuromuscular electrical stimulation (NMES). NMES induces muscle contraction using electric impulses born from electrodes on the skin in close proximity to the desired muscle to be stimulated. This system works because the electrical stimulation from the electrodes mimics neuronal stimulation derived from action potentials.

Proponents view NMES as an effective strategy for increasing muscle mass, muscle endurance, maximal voluntary strength, neural drive and oxidative metabolism, which could also increases immune system activity.13 With these changes proponents believe that NMES could have a positive effect on reducing muscular atrophy. While NMES may have the ability to induce these increases relative to not exercising, there are two important questions that have yet to be answered. The first question is whether or not NMES can outperform the current exercise regime utilized by ISS astronauts?

For example in one study despite aerobic exercise for 5 hours per week at moderate intensity and resistance exercise performed 3-6 days per week at 2 hours per day calf muscle volume in astronauts decreased by 13%, peak power decreased by 32%, force-velocity reduced between 20 to 29% and there was a 12 to 17% increased shift between fast twitch muscle to slow twitch muscle.14 This study and others support the idea that current vigorous exercise designs are not sufficient to ward off significant muscle atrophy hence why most ISS habitation is a maximum of six months.

Unfortunately there is little evidence to suggest that NMES is superior to voluntary endurance and strength exercises because there is almost no evidence comparing the two methodologies in well-designed and properly controlled studies. Another concern related to this comparison is the lack of specifics regarding the biological changes that occur when an individual is exposed to long-term NMES. Finally the second important question creates a logical belief that NMES is not equal or greater than normal voluntary exercise.

This second major question is how does NMES affect muscular fatigue? In humans despite using several different stimulation patterns, frequencies under 16 Hz were not strong enough to produce a contraction that extending a quadriceps to at least 40 degrees.15 Therefore, most stimulation methodologies, depending on the overall type of intervention, utilize frequencies between 20-50 Hz.16,17 This magnitude of frequency creates a non-selective, spatially fixed (due to the continuous nature of the pulse) and synchronous motor unit recruitment.18-20 The immediate interesting element is that these characteristics of recruitment are different from that which occurs in voluntary muscle contraction, which is governed by the Henneman’s size principle.21,22

The evolution of muscle firing and recruitment is shown in the size principle where smaller more fatigue-resistant motor units are activated first followed by larger units if necessary; these larger units can also replace de-recruited units that drop out due to fatigue.23 This process creates an efficient firing recruitment system that maximizes muscular endurance and reduces overall fatigue and its negative effects. However, NMES has a more random simultaneous recruitment instead of organized sequential recruitment, which eliminates fatigue-reducing mechanisms. Unfortunately the level of this non-selective recruitment is not uniform, but seems almost dependent on what particular muscle group is being stimulated.24,25 Another concern with this change in recruitment is how non-selective recruitment for approximately 6 months could influence the long-term functionality of normal voluntary movement when NMES is eliminated after arriving on Mars. Basically will there be any long-term negative effects when “retraining” muscles for size recruitment rather than random recruitment?

Also this increased rate of fatigue may explain why fast twitch muscle fiber tends to morph into slow twitch muscle in NMES patients13 as slow twitch muscle is more resistant to fatigue. This conversion is troublesome because as discussed above, for some reason slow twitch muscle tends to be more prone to atrophy versus fast twitch muscle. Thus this muscle conversion could handicap the ability of NMES to ward off muscle atrophy versus voluntary muscle exercises.

A third concern is that surface-stimulating electrodes apply current directly beneath the surface of the electrode. However, because the electrodes are on the surface the currents they produce need to travel through various subcutaneous tissues with a diverse level of resistances. One study calculated that this impulse was only able to reach superficial motor units 10-12 mm deep and had difficulty reaching the larger motor units deeper in tissue.26 Therefore, an increase in pulse width or amplitude would be needed to improve penetration to reach these other motor units. This “incomplete” penetration may also explain the non-selective motor unit recruitment seen from NMES. Another problem with the localized influence of the electrodes in NMES is the potential damaging effect of the isometric contractions. Multiple studies report significant increases in creatine kinase, macrophage infiltration, z-line disruption and increases in muscle soreness.27-30

A fourth possible issue with NMES is the lack of full neuronal activation. With the stimulation origin focused on a single location at a specific muscle group there is the potential for reduced neuronal coordination with other critical systems. For example some believe that one of the keys to effective muscular endurance and overall muscle health is not only consistent muscle exercise, but also the sequence that begets the activation of the muscle including proper interaction between the muscle, the heart and respiratory systems, something that escapes current NMES protocols. Basically for voluntary muscle movement the neuronal signals originate in the brain and are able to coordinate the appropriate timing on heart, respiratory and other important associated systems whereas NMES skips this activation and relies on feedback to start the process.

Some have thought to increase the effectiveness of exercise to neutralize atrophy through increasing circulating concentrations of growth hormone, various other steroids and/or insulin-like growth factor 1 (IGF-1), which is the main effector molecule for growth hormone, by either augmenting muscle growth or using proteolytic inhibitors to reduce muscle degradation.14 There are some preliminary studies that demonstrate a synergistic effect between growth hormone and exercise in reducing atrophy, but a lot more work needs to be done to establish a positive correlative protocol. For example chronic delivery of growth hormones and other protein growth factors is troublesome because they have short half-lives and damaging side effects in either large quantities or over long periods of time, which right now is required to augment muscle growth.31,32

When addressing safety a chief concern is about the total time an individual could remain in torpor (approximately 180 days). Some advocate hibernation in shifts where one individual is always awake and switches with another individual every x number of days. Even without a defined length of time for being both awake and in hibernation, the biggest immediate concern with this recommendation is how the body would cope with constantly moving between a hibernated and non-hibernated state. For example how would various enzymes and other proteins, which have a very short temperature range of activation, handle 6-7 cycles of being at 92 degrees C for 21 days and then 98.6 for 7 days? While some could argue that hibernating mammals, like bears, periodically roust themselves safely from torpor during their hibernation cycles before reentering hibernation this argument appears invalid because these creatures have evolved to hone the safe application of this behavior, humans have not.

Also the process of therapeutic hibernation is similar to flying in a plane where the most dangerous aspects are the entrance (takeoff) and awakening (landing); numerous entrances and awakenings from hibernation would only increase the probability of a critical failure resulting in serious health damage or death. Overall at this moment it is difficult to argue in favor of a hibernation “shift” strategy. If one is concerned about relying on 100% automation, it stands to reason that one person should remain active for the entire flight with remaining crewmembers in torpor.

Another question regarding the application of torpor is the loss of in-transit preparation time. While it is ideal that all of the colonists are sufficiently prepared for their specialized tasks when arriving on Mars, there is a significant unknown to how well they would retain this knowledge and training. During the transit, it is reasonable to suggest that most of the time would be spent honing their abilities and skills that will be applied upon arriving on Mars to reduce the probability of critical errors during the colonization process. In a torpor state this additional preparation time is lost. Therefore, it is important to consider how knowledge and skills will be retained both in general and within a torpor state.

While the benefits of placing numerous, if not all, astronauts traveling to Mars in a torpor state for the duration of the transit appear attractive there are two major issues that must be addressed. First, the safety of the methodology must be thoroughly analyzed. On its initial face determining safety may be quite difficult for two reasons: 1) the process of therapeutic hypothermia has only ever been significantly tested on people with severe injuries, not people with high levels of health, a characterization that would comprise all prospective Mars colonists. However, what type of “healthy” individual would volunteer to be placed in a 1-month, 2-month, 3-month, etc. torpor state to determine the positive and negative effects on his/her body? 2) all major testing would more than likely occur on Earth to ward off accidental loss of human life due to the ability to immediately act if anything goes wrong; however, without observing how the body would react in a microgravity environment versus the natural gravity environment of Earth creates holes in the knowledge of how the body changes over time while in hibernation during travel.

Second, it is well known that muscle atrophy is one of the biggest threats to the success of a long-term off-Earth colonization mission. At the moment there is little reason to suspect that NMES will be able to ward off atrophy at a similar level to existing exercise protocols let alone surpass their effectiveness. It does little good to save food and space in transit when colonists will simply suffer major muscle injuries upon waking up and moving around for the first time in half a year. Also the question of erosion of colonist skills is one that must be addressed because it would be unnecessarily risky to expect colonists to re-learn skills after landing on Mars. Overall while the idea of inducing a torpor state in colonists during transit to Mars is an interesting one there are numerous smaller questions as well as a few larger questions that must still be addressed as well as some potential technology hurdles before this strategy can be considered viable.

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Citations –

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2. Sessler, Daniel. “Thermoregulation and Heat Balance.” Therapeutic Hypothermia. Ed. Mayer, Stephen and Sessler, Daniel. Marcel Decker: New York, 2005.

3. Vandenburgh, H, et Al. “Space travel directly induces skeletal muscle atrophy.” FASEB J. 1999. 13:1031-1038.

4. Stewart, D. “The role of tension in muscle growth.” In Regulation of Organ and Tissue Growth (Goss, R. J., ed) 1972. 77–100, Academic Press, New York

5. Goldspink, D, Garlick, P, and McNurlan, M. “Protein turnover measured in vivo and in vitro in muscles undergoing compensatory growth and subsequent denervation atrophy.” Biochem. J. 1983. 210:89–98

6. Narici, M, and de Boer, M. “Disuse of the musculo-skeletal system in space and on earth.” Eur J Appl Physiol. 2011. 111(3):403-20.

7. Fitts, R, Riley, D, and Widrick, J. “Functional and structural adaptations of skeletal muscle to microgravity.” J Exp Biol. 2001. 204(18):3201-8.

8. Schollmeyer, J. “Role of Ca2+ and Ca2+-activated protease in myoblast fusion.” Exp Cell Res. 1986. 162(2):411-22.

9. Barnoy, S, Glaser, T, and Kosower, N. “Calpain and calpastatin in myoblast differentiation and fusion: effects of inhibitors.” Biochim Biophys Acta. 1997. 1358(2):181-8.

10. Haddad, F, et Al. “Atrophy responses to muscle inactivity. I. Cellular markers of protein deficits.” J Appl Physiol. 2003. 95(2):781-90.

11. Sandri M. 2008. Signaling in Muscle Atrophy and Hypertrophy. Physiology 23: 160-170.

12. Bodine, S, and Baehr, L. “Skeletal Muscle Atrophy and the E3 Ubiquitin Ligases, MuRF1 and MAFbx/Atrogin-1.” American Journal of Physiology – Endocrinology and Metabolism. 2014.

13. Maffiuletti, D, et Al. Neuromuscular electrical stimulation training induces atypical adaptations of the human skeletal muscle phenotype: a functional and proteomic analysis. J. Appl. Physiol. 2011. 110:433-450.

14. Trappe, S, et Al. “Exercise In Space: Human Skeletal Muscle After 6 Months Aboard The International Space Station.” Journal of Applied Physiology. 2009. 106:1159-1168.

15. Crevenna, R, et Al. “Neuromuscular electrical stimulation for a patient with metastatic lung cancer–a case report.” Support Care Cancer. 2006. 14:970–973.

16. Chhabra, D, and dos Remedios, CG. “Cofilin, actin and their complex observed in vivo using fluorescence resonance energy transfer.” Biophys J. 2005. 89:1902–1908.

17. Coffey, V, and Hawley, J. “The molecular bases of training adaptation.” Sports Med. 2007. 37:737–763.

18. Gregory, C, and Bickel, C. “Recruitment patterns in human skeletal muscle during electrical stimulation.” Phys Ther. 2005. 85:358–364.

19. Jubeau, M, et Al. “Random motor unit activation by electrostimulation.” Int J Sports Med. 2007. 28(11):901-4.

20. Doucet, B, Lam, A, and Griffin, L. “Neuromuscular electrical stimulation for skeletal muscle function.” Yale Journal of Biology and Medicine. 2012. 85:201-215.

21. Henneman, E, Somjen, G, and Carpenter, D. “Functional significance of cell size in spinal notoneurons.” J Neurophysiol. 1965. 28:560–580.

22. Vanderthommen, M, and Duchateau, J. “Electrical stimulation as a modality to improve performance of the neuromuscular system.” Exerc Sport Sci Rev. 2007. 35(4):180-185.

23. Carpentier, A, Duchateau, J, and Hainaut, K. “Motor unit behaviour and contractile changes during fatigue in the human first dorsal interosseus.” J Physiol. 2001. 534(3):903-12.

24. Bergquist, A, Clair, J, and Collins, D. “Motor unit recruitment when neuromuscular electrical stimulation is applied over a nerve trunk compared with a muscle belly: triceps surae.” J Appl Physiol. 2011. 110(3):627-37.

25. Thomas, C, et Al. “Motor unit activation order during electrically evoked contractions of paralyzed or partially paralyzed muscles.” Muscle Nerve. 2002. 25(6):797-804.

26. Fuglevand, A, et Al. “Detection of motor unit action potentials with surface electrodes: influence of electrode size and spacing.” Biol Cybern. 1992. 67(2):143-53.

27. Aldayel, A, et Al. “Comparison between alternating and pulsed current electrical muscle stimulation for muscle and systemic acute responses.” J Appl Physiol. 2010. 109:735–744.

28. Aldayel, A, et Al. “Less indication of muscle damage in the second than initial electrical muscle stimulation bout consisting of isometric contractions of the knee extensors.” Eur J Appl Physiol. 2010. 108:709–717.

29. Jubeau, M, et Al. “Comparison between voluntary and stimulated contractions of the quadriceps femoris for growth hormone response and muscle damage.” J Appl Physiol. 2008. 104:75–81.

30. Mackey, A, et Al. “Evidence of skeletal muscle damage following electrically stimulated isometric muscle contractions in humans.” J Appl Physiol. 2008. 105:1620–1627.

31. Meling, T, and Nylen, E. “Growth hormone deficiency in adults: a review.” Am. J. Med. Sci. 1996. 311:153–166.

32. Hintz, R. “Current and potential therapeutic uses of growth hormone and insulin-like growth factor I.” Endocrinol. Metabol. Clin. N. Am. 1996. 25:759–773.

Laundry on Mars

One of the back burner issues involved in the colonization of Mars is how will colonists do laundry? It seems like a rather simple question and a general task that is taken for granted, especially with the convenience of the developed world. However, on Mars heavy conservation of both energy and water will eliminate both conventional machine washing or even hand washing. So with these significant limitations how will Mars colonists clean their clothing?

Looking towards the behavior of astronauts on the International Space Station (ISS) does not provide any immediate assistance. While it is standard procedure for astronauts on the ISS to wear clothing for longer than a 24-hour period, its close proximity to Earth allows for simple clothing replacement during cargo missions with dirty laundry being burnt up during re-entry. This re-supply process is obviously not available for Martian colonists because additional clothing will add weight and cost to the initial launch and in addition to these negative elements will also take months to arrive in any supplementary launches. Another non-helpful aspect is that most conventionally worn clothing by astronauts visiting the ISS is not specialized in any real sense beyond having a reduced number of seams (or being seamless) with Cabelas and Lands End seemingly being the more prominent brands worn.

With the difficulties associated with cleaning and/or providing new clothing after the initial launch some could argue that after the habitat is established clothing may not be necessary. A well-kept habitat would have a comfortable temperature between 65 and 80 degrees F with little humidity. A lack of non-human origin microbes eliminates any direct infection issues. An air lock separates the preparation staging area for extravehicular activities (EVAs) and the remaining living area of the habitat eliminating the incursion of any negative outer environmental elements. Psychological evaluations and training can manage any potential colonist “revulsion” towards interacting with their nude crewmates. However, while the major immediate issues for accepting nudity appear manageable there are a number of smaller issues.

One of the less heralded benefits of clothing is absorption of general excretions like sweat, shed skin cells, etc. Without clothing there is a much higher probability that these excretions are deposited on various solid surfaces within the habitat, which would not be hygienic and could even damage equipment. Also clothing offers a secondary protective barrier to wards off various ailments that could breach the skin like burns or various cuts and scratches. This additional protection would also serve as a valuable psychological assurance when performing maintenance on various life support systems like waste disposal/recycling or when creating new parts in situ within a prospective machine shop. Not many individuals would be comfortable sanding/welding something with only eye protection.

Some rudimentary experiments have been conducted with some more specialized clothing options like the Japanese Space Federation’s “J-wear”, which includes underwear, shirts, pants, and socks made from cotton and polyester and purports to be anti-bacterial, water-absorbent, odor eliminating, antistatic and flame retardant. Most likely this material has these properties because it is doped with titanium oxide (titania or TiO2) and some other additives. However, the actual testing of this material is limited, especially in its publication, so the time frame for the efficacy of these claims is unknown. One “famous” study with a Japanese astronaut on the ISS created some anecdotal evidence that underwear can retain a chiefly non-offensive odor when worn for around one month.

The reason TiO2 is effective at creating the cleaning advantages is because it is a potent photocatalyst that is able to neutralize the staining of almost any organic compound when exposed to ultra violet (UV) radiation. When TiO2 is exposed to and absorbs UV it results in excited electrons on the valence band of TiO2. This excess energy promotes electrons to the conduction band creating new negative electrons and positive holes. In the presence of water the positive hole interacts with the water to form hydrogen gas and hydroxyl radicals. The free negative electron reacts with the newly formed hydroxyl radical to form a super oxide anion, which decomposes organic stains. In addition if TiO2 is doped onto a fabric it creates a protective film that provides a bio-static, super oxidative and hydrophilic barrier.

Photocatalytic effects, as described above, can also kill bacteria due to the large amounts of hydroxyl radicals produced during the reaction steps. These hydroxyl radicals also aid in eliminating odors as they breakdown the molecular bonds that comprise most volatile organic compounds (VOCs). Some have envisioned the further evolution of this process by doping the TiO2 with nitrogen and adding silver iodide to make the process applicable to visible light, but this is not necessary because a small portion of the habitat could inundated with a UV light source to act as a “laundry area” of sorts. Also it is unclear how safe the silver doping would be for excess exposure to silver iodide is toxic when ingested and repeated contact with skin can lead to argyria, which turns one’s skin blue. Therefore, it makes little sense to include silver iodide. Unfortunately efficient operation of photocatalysts, including TiO2 requires water, which will be in short supply on Mars. Therefore, testing would have to be performed to determine the length of time between UV “washes”.

With or without TiO2 doping exposure to UV light should be sufficient to eliminate any bacteria growth born from the bodies of the colonists. Therefore, the biggest issue will be odor. Another strategy to eliminate odors may be to incorporate a “Febreze” strategy. The active ingredient in the household odor eliminating product Febreze is hydroxypropyl beta-cyclodextrin. Various cyclodextrins including beta-cyclodextrin, are produced from starch via enzymatic conversion. These elements can theoretically be produced in situ on Mars, but the difficult element would be converting the beta-cyclodextrin to hydroxypropyl beta-cyclodextrin due to the lack of easily available carbon elements on Mars. Therefore, this type of solution may not be prudent.

Overall it is clear that some area of the habitat will have to be converted into a dark room of sorts with UV lights to act as an area to clean bacteria from clothing. Limiting the influence of odor on the psychological well being of the colonists is the principle question. Some could argue that individuals have a tendency to become accustomed to smells, but that desensitization demands a static element to the odors; it stands to reason that if odors are not managed then they will progressively expand in a negative manner, thus colonists will probably never generate an accustomed affinity. Therefore, an odor elimination strategy will need to be incorporated. Determining between either an “Febreze” chemical strategy versus a photocatalytic strategy will involve identifying the production capacity in situ of the desired odor eliminating chemical and the amount of water that will be required to active that phootcatalytic effect to sufficiently remove odor. This information can be easily determined in a long-term Martian colonization simulation study performed on Earth, which sadly do not yet incorporate such testing.

Training for Mars – Mind over Matter

In the laundry list of requirements for the colonization of Mars one important issue that is commonly placed on the back burner is the type of training that will be required for the colonists. The success of any Martian colonization mission will depend on how colonists handle new psychological experiences that will affect their behavior as well as their internal biology. Any belief that current NASA training will be sufficient is shortsighted. The most significant difference between performing scientific experiments on the International Space Station (ISS) and building a colony on Mars is the dearth of resources. While resources are limited on the ISS re-supply from Earth is just a few days away whereas any re-supply from Earth for a Martian colony is at least six months away (three to four months if new propulsion technology is developed). Therefore, not only must potential colonists be trained in certain colony critical specializations, but they also must have appropriate physiological and psychological training to ensure a maximized probability of success.

There are typically two types of astronauts: pilots and mission specialists. Due to the requirements of pilots to fly the launch craft and command missions their training focuses on space station and launch craft systems as well as leadership whereas mission specialists are trained in operation of robotics, spacewalks and other modalities for their specific scientific research. Joint training is also conducted in numerous simulators to emulate the vibrations and noise associated with take-off, guidance for payload docking, and buoyancy training in a pool to emulate movement in a weightless environment. Additional water training involves becoming SCUBA certified and endurance training (i.e. 75 consecutive meters of swimming in a flight suit and treading water continuously for 10 minutes in a flight suit).1 To appreciate the importance of current NASA astronaut training, a six-month mission to the ISS typically involves up to five years of training.

Psychological training will be the greatest difference between current astronaut training and future training involving Martian colonists. Currently the psychological makeup of an astronaut can have breaking points because most of the problems on the ISS can be resolved either through a simple EVA or assistance can be quickly dispatched from Earth. Also mission durations are typically only three to six months, thus any negative influences of monotonous actions or interactions with other crewmembers is limited in scope where astronauts depart before reaching their breaking points. However, for colonists there are no escape routes; problems with the equipment, one’s own self and/or other individuals will have to be addressed. While telecommunications will produce some minor outlets to seek professional counseling to manage some problems, other environmental problems cannot be resolved with outside assistance and instead will require adaptation or increased resolve.

Colonists will also be faced with various psychological stressors or “asthenia” [depressive and dissociative symptoms]. In the past these stressors have typically been divided into three stages: 1) an acute phase with a maximum duration of two months brought on by general biological and psychological adaptation to new surroundings; 2) an intermediate phase with more defined and persistent symptomatology including physical and mental fatigue, irritability and motivation loss; 3) a long-duration phase where the intermediate phase symptoms become permanent to the environment and cause significant damage to performance and intra-crew relationships.2-4

One of the most prevalent psychological stressors facing colonists is how to react to new physical limitations. For example colonists will experience a consistent feeling of physical fatigue due to a lack of sleep, lack of calories, limited ability to refresh (meditation, showers, sex, etc.) and a lack of complete nutrition born from balanced vitamins and minerals. Finally there is a large unknown with regards to nutrient absorption for no one really understands how reduced gravity and reduced calories will change a colonist’s microbiota. This change could increase calorie and nutrient absorption limiting reduced energy symptoms or decrease it further reducing energy levels.

It stands to reason that the notorious type A personalities will have difficulties adjusting to this “new normal” because of such a significant reduction in productivity and energy levels. The ability to neutralize frustration will be a key attribute to warding off negative psychological elements associated with this increased physical fatigue. In addition colonists will need to effectively budget their time to compensate for the reduced energy (i.e. work smarter due to it being more difficult to work harder).

Training to handle an increase in physical fatigue is an interesting issue. On its face one would think that the best way to prepare for this environment would be to emulate it. Potential colonists would have a restricted diet (similar to the one on Mars) and reduced sleep (4-5 hours) to psychologically experience the new physical reality on Mars. However, one question arises with this strategy, when should the “simulation” end? If this strategy is to expose and even acclimate colonists to the physical realities on Mars should it even end, i.e. should the Mars colonization mission simply extend the experiment?

Basically the question comes down to what is more important: ensuring the colonists are at peak physical health immediately before starting the mission, yet also have psychological awareness of how they will physically respond on Mars or not allow their bodies to reacclimate to normal conditions avoiding any discomfort associated with going through the physical adjustment again? In essence is the purpose physical adaptation or mental adaptation? If physical then the “simulation” should not end, but instead simply flow into the launch, if mental then the “simulation” should end with sufficient time for physical recovery before the launch.

A good analogy for this question is to think about a person that will need to tread cool water for two straight hours. Does the person enter the water five hours before the test begins to get them mentally and physically familiar with the temperature of the water and how it will affect them, then the individual leaves the water until the time of the test or does the person enter the water a half-hour before the test to allow his body and mind to acclimate to the change in temperature and then remain in the water until the test begins? Barring any strong and consistent negative biological responses among candidates, it seems better to facilitate mental training and preparedness versus physical training (i.e. the first option from above).

The issue of reduced calories creates a type of “double whammy” effect where not only will the reduction in calories reduce available energy creating greater fatigue, but it may also produce physical and psychological pain. Therefore, colonists will need to psychologically train for the reality that they will be hungry a significant portion of the first few years of colonization, especially because boredom/monotony tends to augment hunger due to a lack of attention occupation. The level of hunger will depend on how much money is spent transporting food both in the initial mission and any future supply missions and the level that colonists rest or sleep. If society is willing to spend enough money this potential psychological drawback can be mitigated completely; however, it stands to reason that society will not be willing to make this payment in full, especially with the ecological damage that the Earth could be suffering during the timeframe of the first Mars colonization mission.

Stress management is important both in reducing the probability of occurrence for stressful events and their associated magnitude of influence. Reducing the magnitude of events should be far easier due to much greater levels of certainty and associated preparation mechanisms like biofeedback systems, relaxation techniques, systematic desensitization, meditation and even the consumption of various drugs (if need be). Addressing the probability that stressful and dangerous events actually occur is difficult because one cannot prepare for everything, various things can go wrong during transit to Mars and after landing during the initial colonization period.

Events that unexpectedly occur outside the interaction between two or more colonists are best prepared for through simple decision making training. The most dangerous events are those that have an unpredictable element either in the timing of their occurrence or what is required to solve the problem (i.e. a new problem one did not expect). The reason for such danger is that the probability for poor decisions increases with respect to the lack of relevant knowledge regarding the current situation. Therefore, one important training exercise would be to give prospective colonists numerous tests that involve unexpected events with a lack of certain information.

Individually these scenarios will help develop important types of thought, both lateral and creative thinking as well as enhancing their ability to organize their ideas and thoughts into coherent strategy. These scenarios will also help colonists cope with panic and stress that comes from having incomplete information to solve an important problem. Within a team environment these types of scenarios should help interpersonal interaction through developing a methodology of how the colonists combine their individual efforts and reactions to these unexpected problems to form a cohesive strategy. The purpose of these tests is not to attempt to cover all possible negative scenarios, but instead familiarize colonists to types of thought processes that will increase their probability of successfully solving problem scenarios no matter what type of scenario occurs.

Some of the existing research on military decision making categorized five principal elements to addressing uncertainty (sometimes referred to as RAWFS): 1) Reduce uncertainty by collecting additional information; 2) Make reasonable assumptions to fill in gaps; 3) Weigh evidence and create multiple competing hypotheses (i.e. do not simply create one solution strategy based on existing information, but multiple ones); 4) Forestalling/foresight through development of future solution strategies that may be need to counter problems stemming from the existing solutions; 5) Suppress future uncertainty (i.e. through limiting its relevance or relying on unwarranted rationalization).5,6

Of these five elements the first four are effective and reasonable components to formulating an effective problem solving strategy. However, the inclusion of the fifth element is somewhat controversial. Obviously one could argue that the fifth element is important because it informs individuals not to place unnecessary emphasis on unknown information otherwise that unknown information could create a conflicting response relative to the known information. This reasoning does make sense, but unknown information should not simply be mitigated or ignored because it still plays a relevant role in future events. Simply ignoring something because it is unknown is not the proper strategy to solving a problem. Instead one must anticipate how the unknown information could influence future solutions and plan accordingly based on how the solution will change the scenario both in a positive and negative manner.

Additional psychological training may be necessary to addressing potential interpersonal problems, depending on the construction of the initial colonist crew. A crew comprised of different religions, different cultures, and even different genders will create additional stressors in the colonization process. While from a logical standpoint a homogenous colonist demographic would be ideal from a standpoint of neutralizing these stressors, it may be difficult for the public to accept 4 30 something heterosexual white males being the first colonists on Mars. Therefore, part of the psychological training could involve potential colonists accepting the fact that they would have to give up most of their specific religious and cultural demonstrations due to a lack of resources, space and conflict with those beliefs possessed by other colonists. This adjustment does not mean that these colonists need to give up their beliefs, but they will not be able to exercise these beliefs as publicly as they currently do.

Some may disagree with the idea that individuals would have to restrict their individualistic displays of culture suggesting that the other colonists should simply be tolerant of such actions. This belief is rather irrational considering the scenario involved with Mars colonization. As available resources and space are reduced individual freedom of expression also must be reduced for the sake of harmony. Some would counter this idea with the old Franklin quote, “Those who would give up essential liberty, to purchase a little temporary safety, deserve neither liberty nor safety.” Unfortunately these individuals appear to be arguing for perfect or unrestrictive freedom, which is foolish. Again colonists are not being told that they should give up their cultural/religious beliefs (the essential freedom), but their more demonstrative demonstrations (dispensable freedom). Those who cannot comply with this requirement have a shallow and too rigid belief structure.

Another problem will be a lack of water. Unfortunately some colonization proponents have this “pie-in-the-sky” idea that incorporating a strict water recycling methodology will neutralize the prospect for any water shortages. Clearly while water recycling will be a critical element in ensuring a maximum amount of water availability, a 100% recycling efficiency is impossible. Therefore, there may be times when individuals will have to manage being thirsty. In addition with a reduction in water use individuals will have less ability to wash themselves increasing levels of body odor. Thus, in most situations individuals will have to deal with unpleasant odors from themselves as well as other colonists.

In addition other psychological pressures like the workload and its survival importance (numerous people state that certain things are life or death, but while this is over-the-top hyperbole, on Mars most things will be), lack of privacy, reduced novel sensory stimulation and reduction in familiar social support could all impact mental health. Smart habitat design should create enough personal secluded areas within the habitat to manage any lack of privacy issues. Early in Mars colonization most colonists, especially those who have not previously been astronauts, will have numerous novel experiences; however, these experiences will soon move from novel to monotonous increasing the probability for negative psychological events. The monotonous reality of early Mars colonization can be overcome by simple psychological discipline as well as common enjoyable and personalized actions. Everyone has a favorite song or food or something that no matter how many times they interact with it they never get tired of it, this psychological attribute can assist colonists in neutralizing less enjoyable monotonous events that will be experienced on Mars.

The lack of familiar social support is only illusionary because communication mediums on Earth have created an environment where individuals are able to interact with family and friends in general whenever they want facilitating a form of communication entitlement. When communication ability is restricted this sense of entitlement is broken creating stress; i.e. this stress is not born from a lack of familial support. This rationality is supported by the fact that most individuals do not have meaningful amounts of unique information to share with friends or family when contact is constant. Interaction with family is still possible through restricted telecommunications and email, so overcoming the psychology of not being able to communicate whenever one wants is the real challenge. Pressures associated with the severity of colonization workload and survival can be managed effectively through positive crew interaction and stable meeting periods removing the “individual” mindset and instilling a “team” mindset neutralizing a significant amount of the pressure.

As most individuals recall from their own high school and college experiences the lull of a break from specific study can catalyze the loss of information. Preparation training is important, but over the course of six months of travel to Mars it stands to reason that skills and training will diminish at some unknown variant rate. Therefore, it is important to equip prospective colonists with the ability to review and augment their training in transit. Simulator software packages already exist that emulate in-flight software, but operation of these simulators can become somewhat tedious after a large number of views due to their stiff instructional nature. One idea that could be further explored to break-up this tedious structure is the creation of a competitive instructional platform.

Basically one could focus on creating a game of sorts to augment training; the computer game could resemble a structure like the game “Trivial Pursuit” where players are assigned certain “occupations” that would exist in the process of Mars colonization. Answering questions pertaining to duties and skills associated with these occupations would results in points eventually crowning a winner. Such a system would also benefit other players through creating a form of “osmotic” redundancy where other colonists may not be an expert at occupation x, but would know enough of the necessary skills to take over duties if the expert become incapacitated. The redundancy would eliminate the biggest flaw in a specialized system structure, what to do when a specialist is not long available to perform his/her duties.

Expanding on that idea obviously while specialization is important the subject training cannot be so myopic that only one potential solution is presented for a given problem. Martian colonists need to be trained to think like physicians: make a diagnosis and then determine the best course of action to address the problem. This training must also coordinate between colonists because studies have shown that high performing teams have fewer interaction patterns as well as engage in shorter more concise interactions.5,7,8 Basically for problem A colonists 1 should have a general idea what colonist 2 wants to do. This training strategy should also help the emotional state of colonists for they will not feel intellectually isolated and pressured as the only individuals to have information about subject A.

Some individuals have claimed that it is important to ensure that the medium utilized to augment training is significantly entertaining. While an entertaining medium will make training more enjoyable, it is not an essential element. Remember that the first colonists will be professionals and will have their lives on the line; the expectation that these individuals will not perform necessary training supplementations due to it being “boring” is rather far-fetched. Therefore, it would be beneficial if the entertainment factor for supplementary material could be enhanced, but effort should only be applied in this area after all other important factors have been addressed.

Current medical care in space for severe conditions involves patient stabilization until a launch craft can retrieve the ill astronaut for transport back to Earth. Unfortunately this aspect of training will have to change for a Mars colonization mission because transport back to Earth for medical care will be impossible. Therefore, medical training will have to be expanded to develop the ability to treat a variety of conditions during transit and on the surface with one of the critical medical strategies will be dealing with secondary motion sickness brought on by microgravity negatively influencing the vetibular system in the inner ear due to a reduced responsiveness of the otoliths.9 Other medical emergencies will involve the failure in part or whole of life support, capsule depressurization or fire.

Astronauts typically have one of three types of medical training: basic training for a medical officer, more advanced training for a paramedic and full training for a physician. 75% of astronauts have either experienced a medical event or utilized medication to treat a non-emergent problem.9 Most of these injuries involve, excluding motion sickness, minor trauma to the skin, various muscle ailments due to too much or improper exercise, space motion sickness (which is very common despite preparation training), sleep deprivation, headaches from excessive CO2 exposure and general psychological fatigue.2,10,11

However, there are limitations involved when focusing on the history of medical outcomes in space largely due to small sample size, genetic variation in astronauts, inaccurate historical information due to changes in data storage over decades and inadequate controls to confirm the significance of the data collected.2,12 Despite all of these caveats historical data is still important to consider in gauging what will be expected for colonists during transit and on Mars and should be incorporated into medical training. Unfortunately the biggest variable in expectant negative medical outcomes involves the duration of exposure to a reduced gravity environment. With most astronauts only staying for a maximum of six months on the ISS, it is difficult to gauge what type of medical training colonists need for permanent stay on Mars at 1/3 the gravity of Earth.

Overall with regards to medical care it would be incredibly valuable to have a fully medically trained physician, most likely a general practitioner, among the first set of colonists. One of the principle reasons for the inclusion of a general practitioner is that while training for a Mars mission will be extensive, becoming a physician involves even more training including various real-world experiences acquired as an intern, resident and practicing physician. Therefore, instead of using some percentage of training time creating an individual with skills inferior to a physician on some level, the physician can receive secondary training in another field further enhancing the effectiveness of the crew. Also an effectively trained physician can reduce the amount of required medical equipment, especially with regards to complexity and redundancy, reducing launch costs. Finally trained physicians have unique perspectives and greater understanding of how to deliver treatment over a short, medium and long-term setting.13,14

The progression of how colonists react to changes in their ability to act, in part due to changes in the autonomic nervous system (ANS), is one of the biggest current question marks due to long-term simulation difficulties. The ANS plays a large role in almost all unconscious/subconscious actions and is made up of three different operations: the enteric systems, the sympathetic system and the parasympathetic system. Sympathetic predominance occurs largely when an individual is awake to facilitate engagement with the surrounding environment, especially those that require quick responses and parasympathetic dominates during sleep to facilitate biological recovery.13

The operation of the ANS can change for astronauts. For example some studies of both pre-flight supine position and habitation of the ISS have shown a decrease in mean arterial blood pressure and heart rate15,16 as well as a decrease in parasympathetic activity,17 which could influence sleep quality, alertness and even nutrient processing. However, the pilot portion (105 days) of the Mars 500 isolation study demonstrated an increase in parasympathetic activity with no significant difference in length or phase of sleep-wake periods.18,19 Either parasympathetic activity radically shifts between 105 days in isolation and 180 days in isolation (in space) or this change is cannot be effectively biological modeled naturally in Earth-based simulations. Thus this significant biological change must either be ignored (which is dangerous) or potentially chemical induced during Mars mission simulations. In addition part of the reduction in physical daily activity levels could be attributed to this change in parasympathetic activity, which could also explain the increased amount of rest seen in the Mars 500 study has the experiment went on.19

Another concern may be how sympathetic activity changes with respects to type and duration of light exposure. Typically sympathetic activity increases with color light wavelength20 and light intensity,21 thus prolonged exposure to most artificial lights, which are normally of lower intensity and color wavelength than natural light, could reduce sympathetic pre-dominance. One way to address this problem could be to incorporate different colored LEDs that would make up for changes in wavelength with intensity and visa-versa.

There are two chief subject areas for training: expected events and unexpected events with three sub-subject areas: biological, equipment, and interpersonal. Not surprisingly expected events are the easiest to manage because they are expected, thus only a proper solution methodology is needed to neutralize them when they arise. The problem with the expected events is ensuring that the determined methodologies are recalled and available when needed. To increase the probability of positive outcomes training should involve redundant learning where multiple individuals have knowledge of a given solution. Such an environment can be created where one individual has detailed knowledge of the entire solution strategy and other individuals understand the solution in broad strokes to ensure redundancy.

Unexpected events must be addressed through intensive preparation of generally unexpected events. Due to training and memory time constraints one cannot directly prepare a crew for an event that does not have a reasonable probability of occurrence; however, the crew can be prepared indirectly through engagement with various unexpected events and then observing the solution methodology that the crew utilizes to solve those events. Understanding and editing the methodology that the crew uses to address unexpected problems will maximize their ability to deal with unexpected problems during colonization. Finally interpersonal events differ somewhat from biological or equipment in their unpredictability. Potential negative crew events must first be marginalized through intelligent and practical crew selection, which may need to sacrifice diversity for simplicity. In addition negative crew events can be neutralized through constant team meetings and interactions so no one feels isolated or unimportant. Overall training for a Mars colonization mission should be exhaustive focusing on increasing psychological fortitude, developing team cooperation and producing effective execution methodologies to develop solutions to both expected and unexpected problems.



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Citations

1. Johnson Space Center. “Training for Space: Astronaut training and mission preparation.” NASA. http://www.nasa.gov/centers/johnson/pdf/160410main_space_training_fact_sheet.pdf

2. Bridge, L. “Impact of medical training level on medical autonomy for long-duration space flight.” NASA (TP–2011-216159). Jan. 2012.

3. Grigoriev, A, Kozlovskaya, I, and Potapov, A. “Goals of biomedical support of a mission to Mars and possible approaches to achieving them.” Aviat Space Environ Med. 2002. 73:379-84.

4. Davis, J. “Medical issues for a mission to Mars.” Aviat Space Environ Med. 1999. 70:162-8.

5. Noe, R, et Al. “Team training for long-duration missions in isolated and confined environments: a literature review, an operational assessment, and recommendations for practice and research.” NASA/TM-2011-216162. Oct. 2011.

6. Lipshitz, R, and Strauss, O. “Coping with Uncertainty: A Naturalistic Decision-Making Analysis.” Organizational Behavior and Human Decision Processes. 1997. 69(2):149-163.

7. Orasanu, J. “Crew collaboration in space: A naturalistic decision-making perspective.” Aviat Space Environ Med. 2005. 76:B154-B163.

8. Stachowski, A, Kaplan, S, and Waller, M. “The benefits of flexible team interaction during crisis.” J Appl Psychol. 2009. 94:1536-1543.

9. Wikipedia Entry: Space Medicine

10. Summers, R, et Al. “Emergencies in space.” Ann Emerg Med. 2005. 46:177-84.

11. Scheuring, R, et Al. “Musculoskeletal injuries and minor trauma in space: incidence and injury mechanisms in U.S. astronauts.” Aviat Space Environ Med. 2009. 80:117-124.

12. Cermack, M. “Monitoring and telemedicine support in remote environments and in human space flight.” Br J Anaesth. 2006. 97:101-14.

13. Recordati, G. “A thermodynamic model of the sympathetic and parasympathetic nervous systems.” Auton Neurosci. 2003. 103:1-12.

14. Taylor, J, et Al. “Mechanisms underlying very-low-frequency RR-interval oscillations in humans.” Circulation. 1998. 98:547-55.

15. Verheyden, B, et Al. “Adaptation of heart rate and blood pressure to short and long duration space missions.” Respir Physiol Neurobiol. 2009. 169(Suppl 1):S13–6.

16. Verheyden, B, et Al. “Operational point of neural cardiovascular regulation in humans up to 6 months in space.” J Appl Physiol. 2010. 108:646-54.

17. Baevsky, R, et Al. “Autonomic cardiovascular and respiratory control during prolonged spaceflights aboard the International Space Station.” J Appl Physiol. 2007. 103:156-61 .

18. Vigo, D, et Al. “Sleep-wake differences in heart rate variability during a 105-day simulated mission to Mars.” Aviat Space Environ Med. 2012. 83:125-30.

19. Vigo, D, et Al. “Circadian rhythm of autonomic cardiovascular control during Mars 500 simulated mission to Mars.” Aviation, Space, and Environmental Medicine. 2013. 84(9):1-6.

20. Yasukouchi, A, and Ishibashi, K. “Non-visual effects of the color temperature of fluorescent lamps on physiological aspects in humans.” J Physiol Anthropol Appl Human Sci. 2005. 24(1):41-3.

21. Yokoi, M, et Al. “Exposure to bright light modifies HRV responses to mental tasks during nocturnal sleep deprivation.” J Physiol Anthropol. 2006. 25(2):153-61.

3D Printing … in space

Although 3D printing has existed for years, originating in the 1970s, only recently has it caught the imagination of the public. Numerous optimistic claims have been made about how 3D printing will change the face of manufacturing. One of the more optimistic beliefs regarding 3D printing is how it will change the nature and planning of space colonization, especially prospects for colonizing Mars and the Moon. While on some level such excitement is understandable, it is not appropriate to presume that the inherent problems with incorporating 3D printing into a colonization mission will be solved in the near future or even at all.

For example the most overplayed aspect of 3D printing in a colonization mission is its versatility. Proponents argue that the idea of rationing and scarcity are eliminated in the world of 3D printing. Unfortunately such hopes are rather confusing when compared against reality. The biggest concern for 3D printing is this perceived greatest strength. The versatility of 3D printing is drawn from a blank canvas, but that canvas requires more material than is needed for the particular design in question because what will be needed overall is not known.

Granted the additive process of 3D printing is more efficient at reducing waste than subtractive processes, but waste will exist unless all material is used. At the current stage of launch technology weight is the most important aspect of mission planning as it relates to cost and design. Additional material that will not be used for anything creates additional deadweight costs for the mission. Compare this deadweight cost against a properly planned mission with appropriate organization and logistics and costs should be reduced.

Another problem with costs associated with blank canvases is the volume constraints. Both cost and time exponentially increase to the third power relative to the size of the manufactured product. Basically if one wants to double the size of the product it will cost eight times to produce and take eight times as long to print. The cost and weight issue relative to the canvas also assumes 100% efficiency/reusability when producing an item otherwise the costs and weight required will increase further.

There has been some interest in foregoing the use of Earth-derived source materials and incorporating local surface regolith in the development and maintenance of a lunar or Martian colony.1 While this idea is promising there are still numerous elements that need to be considered before implementation and even if studied may never come to pass (note all of the scientific desires/predictions of last century that failed to culminate into reality even those that attained laboratory success). There is reason to hope though as the European Space Association is teaming with various private corporations to continue to study the necessary processes.

Regolith structure is the chief problem for its use as a source material for while one can create a binding ink that interacts with metallic oxides in the regolith to initiate a crystallization process, regolith on both the Moon and Mars (especially Mars) is heterogeneous with shards of glass, sand and other particles. Also most of the regolith is inert, thus it will have to be doped to form an anhydrous characteristic to increase efficiency.1 The size and surface area of regolith particles is also important, for particles that are too large or too small will create structural inefficiencies and weaknesses, especially if initial results from vacuum reticulation are to be believed.1 Therefore, some mechanism will have to be utilized to filter out particles of inappropriate size.

Somewhat ironically the advantage of the 3D printer in colonization is that of a safety tool versus an efficiency tool. When constructing and expanding an off-Earth colony almost all of the materials will be in-situ limiting the need for inter-planetary resources. Therefore, the additional material designated for use in a 3D printer originating from Earth will largely be utilized in quasi-emergency situations to manufacture semi-critical life support parts. The reason for this limited niche (at this time) is due to the accuracy, power and speed limitations of 3D printing. Common use items will not be created through 3D printing because it is simply easier to provide them during transit reducing costs. Emergency items will typically not be printed because of the time constraints associated with manufacture of the item, especially speed because the most important factor influencing manufacture time is the chemical properties of the utilized material, not the structure/design of the 3D printer.

Additional concerns that will hopefully be addressed in the future are how micro-gravity, inconsistent air pressure and greater temperature shifts will affect the manufactured products. Made In Space has conducted some small short-term tests, but the range of tests does not produce much practical information for long-term utility. Also the biggest current problem for 3D printing is the limited ability to manufacture an item derived from only a single source material, at the moment plastic is typically used. The principle reason combining materials is not applicable at the moment is most materials of significant structural difference (various metals, plastics, etc.) have melting temperatures hundreds to thousands of degrees apart creating structural problems in alloy creation. Some small advances have been made in regards to incorporating electronics, but this type of manufacturing is still in its initial prototype stage. In space colonization some of the other concerns with 3D printing like required CAD blueprints and prototyping are not significant, but it does limit the usefulness of 3D printing largely to the expected “unexpected”.

However, another significant concern for creating quasi-emergency parts is the inaccuracy of 3D printing. Most popular news stories about 3D printing fail to mention that currently 3D printing has a common error rate of about +/- 0.1 mm for various materials. For critical smaller life support parts such error rate may be too costly. Also this error rate may increase due to changes in post-build cooling temperature and micro-gravity environments, which will be more prevalent in colonization missions. Finally current 3D printing commonly produces products that have inferior tensile strength versus standard manufacturing. The additive methodology through the layered construction creates a laminate weakness due to incomplete bonding between the Z-axis and X and Y planes.

Overall at the moment the idea that a 3D printer can revolutionize space colonization should be more reserved. Part of the problem is the limitations of 3D printing, especially with the costs associated with the blank canvas materials that currently need to originate from Earth. The niche role of 3D printing also may need to be expanded to justify its inclusion in colonization missions. Additionally most 3D printer colonization enthusiasts forget that the rise of 3D printing has not occurred alone, but in consort with casting, laser cutters, mills, lathes and routers as an entire manufacturing process. Finally more than likely years of testing will need to be conducted in space type environments like on the International Space Station to gauge the effectiveness and problems with 3D printing in these environments, including situations of very low power. Therefore, 3D printing in space may require such a culmination of various operating and manufacturing elements versus just a single 8’ x 8’ rapid prototyping unit.
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Citations -

1. Ceccanti, F, et Al. “3D printing technology for a moon outpost exploiting lunar soil.” 61st International Astronautical Congress. Prague. 2010. IAC-10-D3.3.5 1-9.

Building a Habitat for Colonizing Mars

Leaving the confines of Earth to colonize Mars will be a daunting task with numerous new challenges. Questions range from how to design the appropriate flight plan to arrive safely on Mars to the psychological makeup of the traveling astronauts. One important question that has evolved recently is the design of the initial Martian habitat. The most important element when considering habitat design is to establish the purpose for the mission to Mars. Early on in the quest to travel to Mars the principal goal was for scientific purposes, largely establishing whether or not life had ever existed on Mars or currently exists on Mars. However, over time this motivating factor has begun to shift towards developing a permanent human presence on Mars. Clearly habitat design will demand different boundary conditions between a mission designed to last 6-18 months and a mission designed to last indefinitely. This post will apply a permanent stay boundary condition in the discussion regarding Martian shelter design.

One of the first issues in Martian colonization is the preparation element. One concern with current preparation is the nature of how the “need” methodology is designed for Martian colonization simulations conducted on Earth. Most colonization simulations take place on Earth in remote locations like various deserts (Mars Desert Research Station) or in Arctic areas (Flashline Mars Arctic Research Station) and are undertaken with the correct spirit and attitude, but appear to have significant design problems. The characteristics that are correct involve the isolated environment and limited resource availability and capacity. However, the usefulness of a simulation stems from the commonalities that can be demonstrated between the actual environment and the simulated environment. In this mindset these colonization simulations fail at least on the following levels, if not more:

- The task schedule described in these simulations for the participating crewmembers seems inaccurate relative to what colonists on Mars will be doing. In simulations tasks revolve around maintenance of machinery, simulated research and shelter-based chores. There is no construction of additional shelter elements, which will comprise significant amounts of time for colonists or farming. To be fair some simulations were conducted with a research mindset over colonization (18-month stay before a return); however, with the current momentum for Mars missions shifting from research return missions to permanent stay colonization, construction of additional shelter elements using Martian based resources (in-situ) and developing an independent food production system should take precedence over research and chores.

- Food consumption is too “well-developed”. In these simulations “colonists” have a wide selection of food available, most of which will not be available on Mars. It stands to reason that there will be some initial variety born from the food transported with the colonists (albeit most of this, if not all of it, will be dehydrated or freeze dried due to the travel time between Mars and Earth). However, this initial source food will be consumed over a brief period of time and less hardy choices will be relied upon for a significant time period afterwards. The “food” study aspects of these simulations do not properly represent starting or transition points. This misrepresentation reduces the probability of collecting accurate information pertaining to how biological functions would change over time and how colonists would have to adjust when consuming significantly fewer calories.

- Modes of transportation operate on diesel or gasoline instead of electricity or methanol as they would on Mars.

- Water extraction and consumption is not practiced in the same manner as will need to occur on Mars. There is no water extraction from simulated ice, no atmospheric extraction, limited water recycling and no experimentation involving water synthesis from the Sabatier reaction. Consumption is managed a little better with personal hygiene restrictions, but unclear parameters regarding actual biological consumption.

These are just some of the limitations that create problems in developing an accurate understanding of the physical, mental and psychological elements that will be required for colonizing Mars. Without addressing these concerns conducting similar future simulations may be more harmful versus not performing any simulations at all because it is more dangerous to create a targeted strategy born from inaccurate boundary conditions and situations than not create a targeted strategy at all.

While both food and water consumption and development strategies will be discussed in much greater detail in another blog post it is important to note that there are questions to whether or not colonization proponents are overestimating the ease of water use, thus underestimating the probability of water stress and shortage for Martian colonists. It is to be expected that water use for personal hygiene will be restricted (showers will be allowed every x number of days based on a rotating schedule baring emergency, dish washing could use UV treated sponges verses water and soap, etc.). Water use will also have to be rationed for personal use (both direct consumption and in food preparation) and this rationing will need to be effectively measured for too many seem to believe that biological water expenditure will be similar to that on Earth, which does not appear to be effective reasoning. Numerous external vehicle activities (EVAs, although one could rename this exercise as ECA (external colony activities)) and multiple hours of exercise per day will place an excess workload on colonist, which should demand greater water and food consumption over the minimum survival amount, a value that most calculations utilize.

Energy for the colony should be derived almost entirely from electricity with the best option being some form of small modular nuclear reactor with breeding capacity. Such a reactor will not produce significant waste so disposal will not be a major issue and the reactor will be able to provide a near 100% capacity rate, something that no other energy medium situated on Mars can achieve. Reactor location is still tentative because of uncertainty relative to how radiation could negatively impact colonists versus the necessary length of transmission lines. If there is a concern regarding potential radiation exposure then reactors can be placed in a nearby crater to offer partial shielding.

Solar power is a popular selection for some colony advocates, but it really is a non-starter because of inconsistencies derived from day-night intermittency, CO2 fog at higher latitudes, dust storms, lower absolute solar radiance on Mars versus Earth, among other things. The only way solar would work is with large amounts of energy storage and only batteries would be available in the short and mid-term significantly limiting storage options and viability due to weight considerations because these batteries would have to be sent from Earth. In addition these batteries would have inconsistencies in their energy storage rates because of the demand for redundancy (most energy consuming elements for the habitat operate 24/7 to ensure survival), but only unused energy can be stored. Finally there are potential oxidation and maintenance issues as well.

There has also been some concern about solar panels being strong enough to withstand wind gusts on Mars, but with the lower atmospheric pressure Martian wind velocities rarely exceed a 4 m/s equivalency on Earth. Thus, only the abrasion resistance is important due to sand particles traveling up to 32 m/s.1,2 Lifting the solar panels above the saltation point (20 cm) can increase abrasion resistance, but the panels will still have to be cleaned constantly creating additional external environment work for the colonists and consume additional resources.3 Therefore, based on all of these issues any proposal to utilize solar power as a primary source of energy is highly questionable. Note that these low equivalency wind velocities as well as its own intermittency eliminate the viability of wind power as well.

Use of solar power as a secondary source of energy is also highly questionable because of intermittency issues. For example in the event of a failure of the small modular reactor for solar to be an adequate backup energy provider the failure would have to occur during the day with clear skies under limited energy demands. Basically the conditions for the successful administration of solar power as a backup source are too narrow to justify its use. If one could develop an effective Martian energy storage system then solar as a backup could become viable, but currently such an infrastructure is not viable due to its dependency on Earth batteries.

The debate between an underground shelter and an above ground shelter is worthwhile for each has advantages and disadvantages. The chief advantage of an underground shelter is additional radiation and dust storm protection. However, the chief disadvantage is digging through the regolith to develop the appropriate underground region to house the habitat. Drilling through the regolith is difficult for two reasons: first, there are almost no easily available fossil fuels on Mars so operational times for drilling equipment would be almost entirely dependent on fossil fuels sent from Earth. One could use methanol as a fuel source, but that would complicated and require large amounts of prep work before sending colonists. Second, Martian regolith is heterogeneous with fragments of glass, coral and other obtuse shaped miscellaneous objects which can significantly interfere with the drilling process by damaging drill bits and other important machine elements.4

Fortunately there are two possible strategies to avoid this problem of regolith drilling. First, regolith does have various iron oxides strewn through it, which opens the possibility of using an electrical attractant or magnetism to thin a significant portion of regolith within a localized area possibly, but not likely forgoing the digging process entirely.4 The chief concern with this method is isolating the regolith to the specific target area due to iron oxides being widely spread throughout all of the regolith.

Second, the underground shelter can be centralized in a lava tube that already has an eroded surface opening so no digging is necessary. In such a scenario a crane/elevator system may be needed to safely lower objects sent from Earth down into the shelter area. Unfortunately while this second possibility sounds promising no organization has even attempted to land a rover in an lava tube, let alone succeeded, thus the prospects of successfully landing a habitat structure (inflatable or not) in a lava tube is a bridge too far in optimism at this point in time.

Another concern with building an underground shelter is the potential for a lack of similar elevation water availability. Some lava tubes double as ice caves, which would have significant sources of water, but where these ice caves are located exactly is not entirely clear.5 Therefore, without identifying at least one easily accessible ice cave, underground shelters would more than likely have less atmospheric and regolith based water sources available versus surface shelters. The best subsurface colonization site would demand three elements: 1) easy surface-subsurface access, preferably from a pre-existing natural opening; 2) a source of ice, which can be converted into drinkable water; 3) sufficient ceiling height and outer area to allow for habitat expansion; unfortunately such goldilocks sites are far and few between at the moment.

For surface-based sites there are three popular locations for initial habitat construction: within the equatorial region of 30 N to 30 S, the edge of the southern polar cap and the northern polar cap.3,6,7 One of the concerns with the reasoning that went into determining these habitat locations is the contradiction between the operations of the habitat and colonists versus the features of the habitat location. In the past when these locations were considered the mission objective was a short stay for scientific purposes; however, how do they rate when the mission objective is changed to a permanent colony? For a permanent colony only two elements are of critical importance: water availability and dust storm frequency.

Other elements of consideration can be easily compensated for depending on the design of the habitat. For example sunlight exposure through changes in inclined angle of incidence is irrelevant if artificial lighting is used. Due to the general sunlight patterns on Mars, the development of an artificial lighting system is appropriate because one will be required anyways to ensure continued flora growth. Other individuals believe that close proximity to sites of scientific interest is important; that belief may be important if individuals were not colonizing Mars, but instead simply traveling for the purpose of research, but in the case of colonization scientific study is far down the list of important considerations for the initial habitat.

While sites closer to the equator will foster external environments with greater temperatures and will reduce internal power requirements for heating, potential water availability decreases as the habitat moves away from the poles. Therefore, colony planners appear to have an energy-water tradeoff decision. Using small modular nuclear reactor(s) to power the colony, energy becomes much less of an issue versus water, thus with regards to this issue the initial colony should be situated closer to one of the poles. Humidity is also an important consideration for it will influence the rate of atmospheric water extraction as well as biological cooling within the contained environment of a space suit during external activities.

Another important factor is the frequency and intensity of dust storms. Dust storms have a higher probability of occurrence in the regions of Hellas, Noachis, Argyre and the Syria, Sinai and Solis Plani in the Southern Hemisphere and in the regions of Chryse-Acidalia, Isidis-Syris Major and Cerberus in the Northern Hemisphere.2,3,8 In general the greatest storm activity takes place between latitudes 20 S and 40 S.8,9 Therefore, based on storm activity potential a colony site in the Northern Hemisphere appears superior to the Southern Hemisphere.

Finally while a polar location appears superior to an equatorial location, a polar landing from Martian orbit is more difficult and offers fewer orbital support options. Therefore, test flights will have to generate an appropriate dynamic for landing successfully otherwise a more equatorial location may need to be selected by default to ensure the safety of the colonization crew. Also note that while targeting has improved from 62 by 174 miles (100 by 280 kilometers) for the 1976 Viking mission to just 4 by 12 miles (6 by 19 km) for the Curiosity rover,10 colonization may demand further improvement due to the limited ability to move the habitat after landing. Overall despite the landing concern the best surface colonization site appears to be near the pole on the Northern Hemisphere.

There are numerous types of habitat design, but with the advancement of plastics and deployment technologies, inflatable habitats seem to be the superior design type. The chief advantage of an inflatable habitat is high space to weight ratio. Increasing the amount of space available for the first habitat is obviously important for psychological and flexibility reasons without significantly increasing launch costs. Another advantage is the lack of complexity in the deployment and functionality for inflatables removing the possibility of requiring secondary structures within the habitat for structural support further reducing costs associated with excess weight despite the fact that various light-weight metals like aluminum would likely comprise these secondary structures.

The chief problem with an inflatable habitat is that it will more than likely provide significantly less radiation shielding either inherently or over time. For example one means to address this concern is to dope laminates into the plastics that makeup the habitat; laminates make excellent shields against debris and even radiation, but when they absorb energy they delaminate, which can create structural abnormalities that are difficult to identify and repair, thus making the doping risky.11 However, this radiation problem can be alleviated through augmenting radiation shielding with additional elements like regolith or human feces.

If an inflatable habitat is utilized space compression will allow for the implementation of a tiered system creating a 1st and 2nd floor. The figures below illustrate one possible layout that can be applied to these two floors incorporating the rooms discussed above.

Figure 1: First Floor of Possible Martian Colonization Habitat

Figure 2: Second Floor of Possible Martian Colonization Habitat

Key:

Floor 1

1 – Outer Hatch
2 – Grey Room/Airlock
3 – Inner Hatch
4 – Primary Life Support Area
5 – Infirmary
6 – Ladder to the 2nd Floor
7 – Secondary Sleeping Quarters
8 – Kitchen
9 – Water Storage
10 – Primary Food Growth Chamber
11 – Filtration/Secondary Life Support Area
12 – Machine Shop
13 – General Meeting and Group Planning Area

Floor 2

1 – Communication Room
2 – Refrigeration Storage
3 – Secondary Food Growth Chamber
4 – Ladder to the 1st Floor
5 – Meditation Room
6 – Sleeping Quarters
7 – Bathroom / Evacuation Area
8 – Research Area 1
9 – Research Area 2

There are two points of consideration for the above figures. First, there are no dimensions on the figures because creating dimensionality requires continuous hands-on experience and access to various habitat structures for testing, something that is not available to me, thus to apply dimensions in any real detail would be rather arbitrary. Second, lacking the dimension specifics may have created what some would argue is an unrealistic expectation to the “carrying capacity” of the habitat. However, the above figures represent elements that could be present in the habitat creating a debate forum between parties for a hierarchical classification of importance among these possibilities. One point of reference is that the Flashline Mars Arctic Research Station has an internal volume of approximately 416.6 m^3, which is a good starting point for debate, but realistically this is probably the minimum volume that should be used. Finally the lines in the figures do not represent physical barriers (walls), but instead are include as space demarcation elements.

One critical aspect of shelter design and operation that has been explored in simulation conditions is the organization and functionality of the crew.12,13 Due to the isolated nature of the crew and the proposed diversity of their assignments it seems important that there be a common area where group meetings could be conducted for debriefs and meals could be fixed and consumed to decompress and bond. Note that these meetings are not designed to be formal. The connections established and reinforced in these group activities will be important to reaffirm trust as well as reduce stress and simple errors during the course of the colonization. It is not surprising that trust is increased when people hear about other people doing a good job at their assigned tasks as well as discuss problem solving strategies with other colonists.12

This group meeting dynamic appears in some simulation environments, but is foregone in others for individual reporting to the commanding officer, a tactic that is less efficient. Overall consistency and casualness are key elements for developing psychological stability and normalcy for new Mars colonists. Also it would also be useful if the central area had a large message board, either a tablet computer or standard white board, that would be used as a display listing the planned activities for the given day and other important announcements.

Formal reports will be required on occasion, but should be limited to only scheduled reports, baring emergency, to limit unnecessary work and also limit stress. For example the only daily report would be the engineering check-in report, which would detail the technical status of all primary life support systems. Informal reports and briefings during meals should suffice for most of the day’s activity.

Expected formal weekly reports would entail:

- the Commander's check-in report (on crew’s overall health, performance and main habitat system status);
- science reports (experiments and preliminary results obtained);
- EVA reports (after each EVA: on duration, range, activity, results, interpretations, etc.);
- Commander’s future report detailing the necessary tasks to be undertaken over the next week;

As mentioned above initial colonization must focus on survival over science. Mars is not going anywhere nor is the environment going through a state of radical flux, therefore, holding off on scientific endeavors for at least six to nine months after landing is rational and appropriate. In fact the first three to four months after landing on Mars easily could involve doing very little “outside of colony work” for immediate tasks would involve required routine operational establishment, life support deployment, exercise, establishing a food growth system and allowing the body to acclimate to the ambient conditions of the Martian habitat including new levels of food and water consumption, which should be significantly diminished from those enjoyed on Earth. A secondary important task after landing would be establishing an autonomous security control system to track any potential external wall breaches and other problems with recycling or synthesis systems to reduce the amount of redundancy involved in colonists checking for these problems during the average day.

Obviously any habitat will require an area devoted to food growth. Numerous individuals envision constructing greenhouses inundated with natural light, but the viability of such a design is questionable. First, the use of natural light to cultivate flora is complicated by the longer Martian day and compounded with the reduced intensity of light exposure, which is approximately 48% versus that on Earth based on distance from the sun and thickness of the atmosphere. Therefore, there are longer consecutive periods of darkness and a longer, but weaker period of light. Some argue that there are numerous occasions of photosynthetic saturation on Earth for various plants, thus less intense natural light would act similar to more diffuse light and would not be a significant detriment to growing plants on Mars.14 Unfortunately light derived photosynthetic saturation is largely a product of long duration exposure to direct sunlight at optimal angles and is rarely a limiting factor to growth of plants on Earth and would be nearly irrelevant on Mars.

Instead of creating an exteriorized greenhouse environment to grow food, lighting can be provided through light emitting diodes (LEDs) at specific wavelengths to encourage growth. Some studies have been conducted regarding the potency of non-while light on planet growth finding that monochromatic red or blue, depending on the particular species, work the best.16-19 There are conflicting reports regarding the usefulness of exposure to monochromatic green light.20-22

The trickiest part to growing most food on Mars will be soil management. Unfortunately native Martian soil will be unable to reliably support food growth for years even after the initiation of a dedicated terraforming program. One solution is to transport soil from Earth to Mars and use that soil as a base inside the habitat (with appropriate temperature and pressure) for a food growth environment. The concern with this strategy, beyond cost, is the base construct of soil is more than just dirt and during the sojourn from Earth to Mars important organic compounds and supporting bacteria more than likely will be lost or altered in such a way that the soil is no longer useful. One potential means to circumvent this problem is cryogenically freezing important bacteria samples prior to takeoff and thawing them for soil insertion during the greenhouse seeding process.

Another popular solution is to forego soil use altogether and grow food through hydroponics. While hydroponics manages the soil concern of food growth on Mars it raises concerns regarding water use. Even with high rates of recycling, water scarcity will be an issue on Mars and growing food through hydroponics will place further stress on that scarcity. Also although soil is not used, a special nutrient mixture is required and it may be difficult to mass synthesize this mixture on Mars after the initial sample is consumed without having some base to work from that must either be created on Mars or sent from Earth.

Another option for food growth is aeroponic growth. Aeroponics attempts to optimize plant growth through the use of a pressurized water mist doped with nutrients sprayed on the entire exposed root system of the plant. One of the chief reasons aeroponics is successful is it does not require soil, which can provide growth inefficiencies due to poor drainage or lack of porosity limiting root aeration leading to reduced growth. NASA has even suggested that aeroponic-based food production through an ultrasonic technique will result in similar yields to conventional growth at 45% greater rates of growth despite using 99% less water and 50% fewer nutrients. However, this conclusion must be tempered with the fact that the comparison is more than likely (it is not really specified) being made against crops raised through flood irrigation and fertilizer saturation, two common yet incredibly inefficient agriculture techniques, thus the actual benefits of aeroponics over more responsible farming is more muted.

The most significant detriment to aeroponics in normal conditions is a higher probability of pathogenic death due to root exposure, but this concern is somewhat mitigated due to the natural aseptic environment on Mars limiting the absolute probability of exposure. Additional sanitary elements can be added to an aeroponics system to limit contamination from colonists. A secondary problem may be synthesis of additional nutrient compounds for the mist for traditional farming develops nutrients from organic compounds and bacteria.

Significant research has been conducted by NASA and other NASA sponsored outside researchers since the early 1990s resulting in several effective water droplet nebulizer technologies and a low mass polymer aeroponic apparatus.23 Some inflatable growth chambers have also been developed for flora growth in space. With that said some argue that a growing area is not necessary in a Martian habitat because aeroponic structures could be incorporated within various other parts of the habitat resulting in more efficient use of overall available space. While aeroponics is viewed by some as the future of food growth in space no serious long-term aeroponic experiments have been conducted in space, so most of the supposed benefits remain theoretical.

Random deployment of aeroponic systems throughout the habitat seems inefficient due to lighting condition confliction. Regardless of growth medium, plants will benefit from exposure to a different wavelength of light over standard white light. As noted above monochromatic blue and red lights have all demonstrated positive growth influences on plants and some positive results have been recorded for green, typically ordering from red to blue to green.20 Therefore, it stands to reason that all potential crops should be exposed to either a red or blue light source preferably from a LED. However, consistent exposure to red or blue light during wakeful hours could have a detrimental effect on the crew. Due to the possible lighting conflict as well as potential sanitation issues localization of food growth to isolated areas of the habitat principally responsible for food growth is advisable.

A problematic element surrounding potential aeroponic use in a Martian habitat is the lack of experimentation for such a system on Earth. Recall above that numerous “Martian Simulation” experiments have been conducted, but none have extensively utilized aeroponics in an isolated environment to support food production. If aeroponics is viewed as a valid option for providing food on Mars why have these simulation experiments failed to incorporate such a testable strategy?

Depending on the final strategy for food growth on Mars one idea for expanding stability and growth potential is to design a small indentation in the habitat that can be filled with water to develop a makeshift aquatic environment for raising fish and other life. While the specific details regarding what could be grown in such a pool will be left for another blog post two possible food candidates are loach and azolla because the azolla can fix nitrogen and suppress any weed growth while loach can survive in higher toxic environments (like high salt) with little detriment or consumption toxicity. Such a survival ability could be important because there will more than likely be periods where the water in this farming pool will be less than ideal and changing consistently it will be difficult to due higher priorities for water.

There are numerous questions associated with potential changes in sleep patterns on Mars. Astronauts on the International Space Station (ISS) use small-individualized compartments, similar to phone booths, to ensure personalization and space constriction. However, on the ISS the microgravity conditions allow these units to be vertical because with insignificant localized body forces the astronauts are able to sleep in any position without negative biological effects. On Mars gravity is only 1/3 that of Earth, but still significant enough that effective sleeping will more than likely require lying down. This requirement limits the usefulness of the phone booth designs utilized on the ISS. Two other options are ceiling/wall hammocks or using the floor of the inflatable habitat as an air mattress of sorts. While hammocks are viewed as a popular option there is a question of how much body, especially back, support they offer over the long-term. Thus, either long-term testing of hammock sleeping in a reduce gravity simulation environment (simulations typically utilize patients sleeping a an angled incline (30-45 degrees) has to be conducted or sleeping on the floor should be used due to uncertain safety concerns.

Another issue with sleep methodology is that experts acknowledge that sleeping environments must remain as homogenous as possible to increase probability of consistent high-quality sleep. Basically physiologically the body and mind must generate an understanding that this “area” of the environment is reserved for sleep not machine work, cooking, laboratory study, etc. Due to the shorter duration of stay (normally 3-9 months) on the ISS, astronauts can get away with more disrupted sleep patterns whereas colonizing Mars will demand a more stable sleep pattern, thus colonists should have some form of personalized sleeping quarters.

Sleeping quarters will need to have opaque shielding over the walls to eliminate any outside light sources, use LED lighting and will also more than likely have to be soundproofed in some manner because of the constant and excessive noise produced by the life support system. Not surprisingly colonists will sleep in shifts to ensure that multiple people are awake over a given time period to handle any emergency situations. Despite the planned shift sleeping the life support system will have a centralized yellow alert alarm that will act similar to a smoke detector when alerting colonists to a potential problem and a red alert alarm system that will act similar to a tornado siren to breach the soundproofing. In addition because of the soundproofing it may be beneficial to have a rudimentary intercom system between the main meeting area and the sleeping area.

As alluded to earlier there is the concern of noise pollution in the habitat, both during the day and night, due to the constant operation of the motors and pumps corresponding to life support function, other machine systems and in-situ processes. One possible strategy to deal with excess noise is to isolate the source limiting the resource and time requirements for soundproofing for all other necessary areas of the habitat. While this strategy could be effective, it typically does not consider the secondary redundant life support elements. Fortunately secondary life support elements should not be a large problem relative to noise production because they will only be on-line if the associated primary element is off-line. Also there will also be sources of external noise like dust storms, which will make soundproofing sleeping areas a high priority. Final designs will have to select between soundproofing the primary life support area, the sleeping area or both.

Whether or not private rooms will be made available or sleeping arrangements will be partnered to save space is a decision that will need to be made before the mission commences. A practical way to determine if partnering is a plausible idea is to have potential candidates sleep in the same room during isolation tests to determine whether specific sleeping habits are tolerable. If yes, then partnering is possible. Finally different forms of LED lighting could be incorporated to improve sleeping capacity and duration both during the process of falling asleep or/and during waking hours. Soft blue-enriched white light is thought to be the best option so far based on existing research.24

Another important element in habitat design that a number of people seem to neglect is whether or not to include a specific area for medical treatment. One response for this exclusion is that such a space is not necessary because there are only a limited number of medical conditions that could befall an individual on Mars versus Earth. For example the lack of pathogenic microorganisms nearly eliminates the possibility for infection (recall that all individuals and equipment will be sterilized prior to launch and the landing area should be thoroughly sterilized via UV bombardment). However, the reduced gravity will increase the probability of bone and muscle injuries due to apoptosis and bone degeneration. The additional demands of exercise could also increase the probability of muscle injury. It is difficult to apply experiences in exercise and the corresponding rate of injury potential from the ISS to Mars because of the difference in intensity of the exercise and the duration required due to length of stay. Therefore, it is unclear whether or not bone/muscle injuries can occur to such an extent that will require surgery (ACL tears, bicep tears, etc).

Without a prepared environment what will happen if someone needs an operation? Can another area of the habitat be prepared accordingly to create an appropriate operation theater? It is difficult to envision the creation of an appropriate area for surgical and other advanced medical procedures from the manipulation of another area largely because of the methodology in handling the blood and sterilization procedures required for successful surgical practice. Note that the probability of an individual sustaining an injury that requires surgery early in the colonization process is unlikely, but the probability of such an injury will increase with time. Therefore, the construction of an appropriate and stable location to conduct surgeries should be high on the priority list of habitat add-ons after initial deployment, but may not be required as a part of the initial habitat design.

The gray zone is the preparation area for EVA activities and separates the internal habitat from the external Martian environment (think of it as an expanded airlock space). Entry and exit will take place through pressurized hatches with the one leading to the surface of Mars denoted as the external hatch and the one leading to the internal habitat denoted as the internal hatch. There will be obvious safety precautions so that both hatches cannot be open at the same time (basically if one is open or opening the other cannot be opened) to ensure the purity of the internal atmospheric pressure by preventing disruption of the colony pressure, temperature and oxygen environments as well as the infiltration of dust that could damage instruments and other machinery. When designing this space the most important elements are airlock volume, airlock-suit interaction, power consumption, compression ratio, pump down rate and thermal cooling rate/method. Of course when the external hatch is opened there will be atmospheric mixing between the gray zone and the Martian atmosphere including the incursion of dust. To address dust in the gray zone a system of blowers will be used to transfer dust to a separate internalized compartment that can release the dust back into the Martian atmosphere.

There are numerous detrimental effects that afflict Earth-born humans in a significantly reduced gravity environment including, but not limited to: 1) Renal stone formation; 2) Diminished immune response; 3) accelerated bone and muscle loss; 4) changes to cardiac and vascular function and architecture.25 Clearly since Mars is a significantly reduced gravity environment these changes will afflict potential colonists although not at speeds equal to those experienced in space itself. One of the chief strategies for reducing the impact of these negative outcomes is a rigorous exercise program.

The lack of gravitational force near to what humans experienced during birth and early stages of development influences bone mineralization, reabsorption, matrix formation due to the lack of the “recognized” external body force that the bone structure developed around.26,27 These problems significantly increase the probability of osteoporosis. On the ISS force applied during foot exercises are dramatically reduced (25% for walking and 46% for running) versus the same exercises on Earth28 and one must expect a slightly reduced reduction on Mars. However, since these changes appear dependent on gravity, both from a standpoint of magnitude and direction, if muscle contractions are large enough intense exercise can act as an effective countermeasure.29,30

Exercise systems currently in use on the ISS are designed for saving space in that the equipment folds into the wall, similar to a Murphy bed, which is smart design. A similar design will need to be utilized for the Martian habitat as well, although a direct copy design could be difficult for an inflatable environment. However, the equipment should be upgraded to higher quality harness systems to increase musculo-skeletal loading. The loss of both slow twitch and fast twitch (type I and II respectively) muscle fibers, with slow twitch losses occurring much faster, demands more effective treadmill systems as well.31,32 In addition to treadmills, various resistance bands, at various levels of resistance, will be utilized as a light-weight, but effective means for tensile strength loading. A lingering question regarding exercise is whether or not a separate room should be reserved for this equipment versus incorporating it into another room?

Most would immediately answer that due to space considerations secondary incorporation would be a better choice over creating a specific space reserved for exercise. However, where would such incorporation take place? Clearly foldout equipment would need to be placed away from sleeping areas, life support, research areas, any areas designed for food growth and more than likely the communication areas (due to desires of privacy and quiet when talking with family, friends and associates on Earth). For most habitat designs this leaves the central meeting room, the gray area and the machining area.

The machining area may not be a practical decision because of necessary work on various tasks. Recall that each colonist will have to exercise a certain amount (usually 2-3 hours) per day to reduce detrimental effects from the limited gravity and it would not be advisable to skip specific sessions. The capriciousness of use for any type of machining or repair, its typical critical nature and unknown time allotment required for the repair will create situations of conflict with scheduled exercise times. The gray area suffers from a similar problem although EVAs can be scheduled creating less uncertainty in time confliction, thus this problem is not insurmountable. Fortunately the general meeting area does not have these types of problems and by default is the best place to incorporate the exercise equipment if it is not given its own area. This hybridization is rather easy to organize with appropriate scheduling assigning specific time to colonists and avoiding exercising during meal and meeting times.

One of the interesting debates concerning habitat development is how to address the psychology of living on Mars. Some believe that incorporating windows will be an important element to maintaining a healthy psychological makeup by providing a connection to the outside world.33,34 However, would such a strategy really provide said benefit for Martian colonists? Having a connection to the outside world/nature is only relevant when there is meaning behind that connection, i.e. when it provides inspiration or support. Any Martian colonists looking out a window will only see a barren rather monochromatic landscape unable to support life… how can such an experience provide benefit? There is also the belief that pictures of nature provide positive psychological benefits, which research supports.33 However, the research focused on individuals in isolation who would later leave that isolation, Martian colonists will not leave Mars, so would this reality lead to such pictures causing psychological detriment over benefit due to colonists lamenting about what they left behind?

Another strategy to produce a connection to nature could be a meditation room. One viewpoint towards food production, which will be expanded on in a later blog post, is for colonists to develop a simple aquatic farming system. The system would consist of a small pond with specific types of fish, algae and other simple life. Periodically this system would be farmed for food and could provide some rudimentary waste neutralization. In addition to providing food such a pond could act as a basis for a more Earth-like environment in the habitat. Some transported soil could be added to the pond environment to allow grass seeding, flowers and/or a very small garden as well as a pump system for the pond to produce a small waterfall (this could also provide better oxygenation of the pond itself); such features would produce an environment that would have a positive psychological effect on colonists.

In addition to providing a “little bit of Earth” on Mars, the room could provide a specific environment for individuals to regain focus and concentration after a bad day or persistent psychological deterioration due to task monotony. Such an environment would improve psychological, mental and physical health improving survival probability across the board. The space used for such an environment would not be significant in the habitat itself or could be “outsourced” to an externally constructed environment built after landing.

However, despite the outlined potential benefits of any of the above systems or others that were not mentioned, one could argue that these techniques to foster psychological benefits are superficial. They only provide benefit to the psychologically weak who are unable to cope with leaving Earth and settling on Mars. Pick the right colonists and adding such psychologically associated features would be a waste of time, space, resources and money. Whether or not this assessment is correct is debatable, thus leading to the aforementioned statement about the debate that will surround any psychological support elements being added to initial habitat design.

While one general goal of a colonization mission should be to mitigate as much critical communication between Earth and Mars as possible with the proper occupational and training selection of candidates, it will be important to design an effective facility to properly carry out interactions between Earth and Mars. The principle reason that one needs to limit critical communication is that there will be an 8-18 minute delay for radio communication depending on the proximity between Earth and Mars in their orbits.35 Video communication will be even longer, which will further limit the effectiveness of real-time support, thus colonists should have the experience and knowledge required to address situations that would have critical time constraints. This time delay also basically eliminates a practical Internet between Earth and Mars for it will take approximately 18-40 minutes to register a single mouse click.36 Cache storing is possible, but it will require a lot of additional work for little benefit.

However, communications between Mars and Earth will also involve non-critical information exchanges either on a professional level (official progress reports to a Mission Control-type organization) or causal/personal level (exchanges between colonists and family/friends). The feasibility and reliability of this communication will be based on two separate elements: inclusion of Ka-Band frequencies (18-40 GHz) relays and incorporation of new Mars-orbit satellite relays focusing on X-band frequencies (7-12.5 GHz).

A secondary important issue to judge communication between Mars and Earth apart from the time delay is the line of sight (LOS) problem where the Sun will produce significant levels of interference potentially eliminating most standard forms of communication for long periods of time. This problem will demand, but not require, modification of the Deep Space Network (DSN). One means for modification is launching numerous satellite relay points various Lagrangian Points. This modification can also provide an early warning system for various types of solar radiation. Unfortunately basic maintenance of the DSN has been generally deferred since the 1990s, thus it is questionable whether or not any improvements will ever be made.

The communication room could also double as a form of entertainment room with a large lightweight projector screen and two or three lightweight computer tablets. The tablets should be loaded with numerous different computer games from simple games like solitaire and scrabble to more complicated games like real-time or turn-based strategy games. The variety of games installed can be determined by gathering survey information from the colonists prior to takeoff. These games should be installed onto the computer so that they do not require Internet access because as mentioned above Internet connections on Mars are very improbable in the first few decades.

While research will be a secondary element in the primary stages of the colonization, it is practical to consider the design of scientific research areas in the habitat. The three most important research subjects on Mars will be biology, geology and chemistry, all requiring significantly different and sometime contrasting study environments. For example geologist will require low illumination and dust availability versus a particulate free and high illumination environment for biologist. Some of these elements are so contrasting that lab sharing is an unlikely solution. Also limiting the number of scientific tools could be a double-edged sword for fewer tools mean less clutter and maintenance, but would also demand more strict cooperation between researchers when using these tools. Overall it appears that research importance should trend from biology as the most important to chemistry then finally geology, so preparations should reflect this importance.

The first colony should have a rudimentary form of machine shop that can be used to facilitate repairs on damaged habitat features or EVA suit parts. For example EVA suits themselves will eventually become unusable, especially if exposed to additional impact damage produced during dust storms. How will damaged EVA suits be replaced? Expecting a “new” shipment from Earth is unrealistic, thus colonists will need to have materials and knowledge to make necessary repairs. However, there needs to be very strict coordination between Earth and the Mars colony regarding re-supply for EVA suits that sustain so much damage that they cannot be repaired. Also a machine shop should store the necessary tools to repair various habitat systems and life support elements.

In addition to the machine shop colonists must create an in-situ resource utilization (ISRU) processing area. Fortunately the major ISRU elements (water and oxygen) can be funneled through the life support system where other ISRU elements (various metals and building materials) can be synthesized in an area external to the primary habitat. Most previous Martian return mission or colonization plans have focused on ISRU to synthesize fuels, both for space travel and surface travel, over other elements. For a colonization mission using electrified modes of transportation with methanol as an emergency backup, there should be less focus on synthesizing fuel from ISRU processes. The need for producing fuel is also diminished in the interim of a colonization mission due to less need for scientific exploration. Instead the focus will be on producing complementary water, oxygen and additional masonry building materials.

Concerning ISRU processes one of the most common proposals for a Martian mission is to use electrolysis on available water, largely derived from settlement at one of the poles, to produce hydrogen and oxygen. While this strategy is used on the ISS, it has never made much sense on a long-term scale for Mars colonization because of the high value of water, the almost non-existent ability to re-supply from Earth and the limited benefit from the produced elements due to other existing synthesis strategies. Hydrogen has little value in initial habitat settlement of Mars. Some view hydrogen as a potential energy source through the use of fuel cells, but this idea makes little sense because there are numerous more efficient means to power the habitat and transportation vehicles, like small modular nuclear reactors, which eliminates the need for fuel cells.

Using hydrogen as a transportation fuel source is also contingent on vehicle design. Hydrogen synthesis is only relevant if methanol is going to be utilized as a transport fuel for rovers. The idea revolves around using electrolysis to create a feedstock of hydrogen for the Sabatier reaction to partially recover some water and produce methane, which is later converted to methanol. However, transport rovers that utilize electrical batteries can be used over hydrocarbon/methanol-based rovers. One could argue a concern about a loss of the battery crippling an electrical rover, but similar crippling events could also come from the loss of various other machine parts utilized by either hydrocarbon-based rovers or electrical rovers, thus the seriousness of such a concern is mitigated by the random fail probability that embodies it. The goal of designing a transport rover is simply to reduce this fail probability to as small a number as possible while maintaining efficient operation. Overall it seems more probable that running out of a methanol fuel would be more troublesome than having a battery malfunction in probability of occurrence. Without any use as a fuel, either for electricity or transportation, production of hydrogen derived from water electrolysis loses its principle purpose.

Oxygen is another product of electrolysis and is an essential element for survival. Unfortunately oxygen production through electrolysis is inefficient because it involves the consumption of another important resource. A secondary method for creating oxygen would involve simply splitting the abundant CO2 in the atmosphere into carbon and oxygen. Such a process will take large amount of energy, but fortunately this energy would be available from a small modular nuclear reactor for it will produce much more energy than the initial habitat will need to survive. Oxygen concentration can further be supplemented through plant and cyanobacteria photosynthesis. However, it is important to note that photosynthesis derived oxygen will more than likely not be sufficient alone. The above analysis has mitigated the importance of electrolysis for the express purpose of synthesizing hydrogen and oxygen, thus there is little point to utilizing it during the colonization of Mars.

Early in Martian mission designs there was the potential need for a cryogenic storage area to store methane, hydrogen and other gases that would be utilized as potential rocket fuel to coordinate a return mission back to Earth. For a colonization mission the importance of the cryogenic storage area is reduced, especially if transportation is electrified over hydrocarbon-based. Any synthesized and/or collected hydrogen will be almost instantly inserted into a Sabatier reaction bed for the purpose of synthesizing water. Methane and other hydrocarbon-based gases do not need to be stored for any legitimate purpose.

However, the colony must have some form of refrigeration capacity for storing food as the efficiencies of harvesting food will not be maximized to the point where there will be zero potential food waste without a refrigeration system. Refrigeration will also be needed to store medical samples and generate ice for dealing with minor injuries. Also it is important to note that water treatment and recycling systems will be mandatory for any habitat, but it must be acknowledged that the lower Martian gravity will increase the rate of time for particles to be taken out of suspension in the recycled water. Realistically this increased time should only significantly affect passive filtration systems, but dependence on active filtration systems will increase energy demands, thus simulations need to be run to determine which system should be incorporated for a given specific process.

An additional element that has been noted in simulations with habitat operation is that storage space is highly coveted for scientific samples from biological and geological study, scientific instruments and personal items.12,13 On Mars storage will not be such a large concern in the interim because there should be a very limited level of scientific exploration/analysis for the first several months. During the process of acclimation one goal may be the construction of an external storage “shed” type structure apart from the initial habitat to alleviate future storage stressors. Digitizing documents would also be standard, not only to save space, but simply due to a general lack of paper.

One potential problem with habitat construction could come from the electrically active atmosphere. While the nature of the concern is strictly theoretical due to a lack of Martian exploration and lack of electrical charging measurements, differential charging in relation to electrified dust (recall that regolith possesses iron oxides) could create electrical discharges between different objects that could damage electronics or interfere with communications at inopportune times.39

The internal habitat environment should have a single atmospheric pressure eliminating the need for internal airlocks ensuring a more simple and efficient build as well as easier travel within the habitat. Despite a single atmospheric pressure, internal gas partial pressures can be adjusted appropriately (CO2 dominating in greenhouse areas and O2 in other areas of the habitat).

All of the primary life support elements should be located within same general area with secondary redundant life support elements individually spread throughout the habitat in case something happens to the core area housing the primary life support elements. The equilibrium values that will be generated by the life support systems will be set prior to launch based on estimated necessities for survival. The ISS has demonstrated a good standing for most of the life support elements that will be utilized on Mars.

Another consideration regarding the placement of primary life support and even secondary life support units is addressing possible radio frequency and electrical magnetic field interference (RFI and EMI). Sufficient RFI will interfere with communications, which given the specific windows of operation for an early Martian colony losing communications with Earth could be crippling. EMI originate largely from power distribution systems due to their large currents and can have a devastating effect on microcircuitry. RFI shielding typically consists of metal membranes or foils whereas EMI neutralizing actually involves simple physical separation of generators and targets. Overall to avoid RFI communication systems should be within their own room and properly shielded.

Although it is a topic that is uncomfortable to discuss what happens if one of the colonists experiences a psychological break and becomes unstable and potentially homicidal? In this potential scenario there must be some form of security measures applied to protect the life support system from sabotage. However, this security must also be lenient enough that if a colonist perishes through non-malicious events that it does not prevent surviving colonists from accessing the life support systems when necessary.

One possibility would be to control the security system from Earth, but would the frequent communication blackouts that occur between Mars and Earth create life or death problems? Unfortunately this system is handicapped by the emergency situation during a communication blackout because any override system would defeat the main purpose of having security control on Earth in the first place. One possible way around this dilemma is to only have the emergency override active when the signal from Earth is down. A second security possibility is to require two positive voice and retina identifications to enter the life support chamber. It is highly unlikely that two individuals would experience psychological breaks at similar times and conspire together to eliminate the rest of the colonists.

There are two aspects of temperature control in a Martian habitat. First, there must be external thermal insulation and reflective foils to eliminate the colder influence of the outside environment, which will frequently be too cold for human survival outside a space suit. Second, there must be a form of internal thermal control to reject or reprocess waste heat to eliminate temperature spikes inside the habitat. This secondary element will normally be controlled by the life support system and there is less need for a secondary redundant system backup because if life support fails there will be bigger immediate concerns than additional waste heat in the habitat.

In additional to controlling temperature, internal moisture control also will be an important element. Increased water vapor will come from colonist perspiration and flora/fauna (depending on the type of insects and/or fish raised in the habitat). If not controlled the excess water vapor will condense on colder surfaces within the habitat. This water condensate will increase failure probability for microelectronics and increase oxidation rates for various metals and other composites. One method to address condensation would be to utilize atmospheric condensers or humidifiers to pull water from the air and water condensate from solids while remembering to strategically place these units away from areas with agents, which require water consumption. On a side note fire elimination will more than likely involve an extinguishing chemical versus water.

Concerning the layout of the habitat shown above in figures 1 and 2, placement of the infirmary on the first floor is entirely practical because most serious injuries will take place either during EVAs or when exercising (both activities occur on the “first” floor and moving these individuals up or down a ladder is unnecessary and could aggravate the injury. First floor placement also makes sense for the purpose of equipment transport. Some form of secondary sleeping quarters should also be made available on the first floor to accommodate injured individuals for it makes little sense to locate the infirmary on the first floor to limit unnecessary transportation to those suffering from certain injuries, but then expect those same individuals to engage in that transportation for the purpose of sleeping and rest.

Due to the heavier equipment that will be transported for the purpose of exercise placement of the exercise area on the first floor is appropriate for weight barring and some of the associated jarring movements, which will occur during exercise. Also as mentioned placement on the same floor as the infirmary is important to lessen injury in transportation. Locating the machine shop operation on the first floor also makes sense again for transportation reasons because most of the operations in this room will involve elements that either originate from outside the habitat (various gases and materials) or interacts with the ambient atmosphere (EVA suits).

The general design of the habitat is to concentrate most of the noise and work production on the first floor due to ease of movement and continuity. Therefore, with most of the habitat-produced noise taking place on the first floor it would make sense to locate the sleeping quarters on the second floor to limit noise infiltration. In addition the sleeping quarters should be placed as far away proximity wise from the primary life support system. In the figures the sleeping quarters are placed in close proximity to some of the secondary life support systems (located on the first floor), but it is more important to ensure a sufficient distance between the primary and the secondary life support systems versus distance between the secondary life support system and the sleeping quarters because in most situations, hopefully all situations, he secondary life support system should not be producing any noise, thus close proximity to the sleeping quarters will not be an issue.

The research area is placed on the second floor to reduce noise and foot traffic in efforts to improve efficiency. Transportation of exterior objects for study is less of an issue because objects will be smaller and lighter. The research area will also be split into multiple sections because as stated above different types of research will demand different types of environmental conditions that could contrast with each other.

Due to collision dynamics of dust and other particles in the atmosphere all organic matter would be best shielded by plastic with additional doped agents for radiation protection; however, structures that will not house organic matter for a long period of time or at all can be constructed from more traditional methods like bricks. Most early brick housing on Earth involved the use of adobe bricks, which are basically dried blocks of sand and/or clay. One of the chief advantages of adobe bricks if their high thermal mass, which provides resistance to rapid environmental temperature changes similar to those that occur on Mars between the day and night. However, unfortunately the Martian day is typically not warm like the Earth day (-50 C versus 10-30 C), thus the thermal properties of abode bricks to store heat with a slow release time has limited usefulness. Another concern with using bricks is the optimal process on Mars involves kiln-like treatment (very high temperatures usually stemming from a chemically generated fire in an oxygen rich atmosphere, i.e. vitrification). Despite the inability to benefit from its thermal properties and the extra processing steps, adobe brick construction is more than likely still the best method for early additional external construction.

Another method of building construction involves either rammed soil cement or cast soil cement. Rammed soil cement is a rather old and widely demonstrated technique that involves mimicking the natural process of sedimentation with soil mixing with water and cement before being shoveled into the proper shape. Applying a significant amount of force and tamping the mixture finish the brick.4 Cast soil cement uses a soil, water and gypsum slurry mixture that is used in wall molds and later dried.4 The gypsum mixture is used to stabilize the slurry. Unfortunately there are two problems with both of these synthesis techniques. First, both require the use of large amounts of water to create appropriate scale sized buildings and water is a pressing resource on Mars. Second, it would be difficult to create these bricks without extensive external work periods, which may not be appropriate in the current Mars environment. Water consumption is also a strong reason for the prohibition of concrete as a building material.

Processing raw materials on Mars for habitat augmentation will be an important element in increasing comfort and safety. The silicate, calcium oxide and other oxides (sodium and potassium) within the sand on Mars can be used to create glass (thermal fusion), but the iron oxide will have to be removed first otherwise the glass will become black glass, which has reduced strength and purity. However, the lower gravity will require a greater processing time during the molten stage to allow for complete bubble removal.38 Glass fibers can also be added to concrete and other building material to improve tensile strength.

The chief problem with glass is without augmentation from laminates the glass will more than likely be too brittle to stand against changes in pressure differentials, which could occur at any life support malfunction or hiccup.11 Basically if the glass is too brittle then if the pressure of the habitat changes in any significant manner the glass could break. However, the concern with laminate doping in glass, as mentioned above, is that laminate absorbs impact energy, which can lead to delaminating resulting in the increased probability of microfractures in the glass eliminating the advantage of the laminate doping in the first place and again these microfractures are difficult to identify without destroying part of the structure, which defeats the entire point of inspecting the structure.

The primary electrical components will range from macro-structures like high voltage and amperage breaker panels and transformers for power conditioning to micro-structures like microprocessors and transistors. Typical building codes for electrical systems should be applied where switch panels have unobstructed access within a secure unit, transformers exist outside the building to reduce fire probability and resultant damage and other major power conditioning equipment is separated from main living areas. “Cold plating” equipment (placing it outside the pressurized environment/habitat) is a debatable issue. Such a strategy is utilized for the International Space Station, but for a Martian colony placing necessary equipment in an isolated secured area of the habitat may be more appropriate because of greater lead times for EVA preparations between Mars and the ISS.

Finally one of the elements that some supporters seem to forget is that it is difficult to imagine a “cheap” Martian colonization mission because of necessary redundancy. With the element of uncertainty and the inability for rescue (remember that Biosphere 2 had numerous catastrophic failures that were remedied due to nearby support), redundancy is the key to increasing safety probability and generating a successful mission. Redundancy encompasses two features: “like redundancy” (multiple copies of the same element) and “unlike redundancy” (single copies of multiple elements that perform the same general function). For example at least two elements for each life support system should be included in the initial colonization habitat unit. Due to necessary redundancy, planning for a colonization mission to Mars must demand intelligent and practical decisions involving where to spend money without cutting corners. The real “cost prohibitive” aspect of a Martian mission would be to do it again because the first one failed due to not properly supplying the initial habitat. This reality is why strict scrutiny needs to be applied to all proposals, but especially those who expect to only spend 4-10 billion dollars on an initial Martian colonization mission.

Overall there are a number of issues that need to be addressed when designing and deploying a suitable habitat for Mars colonization and obviously that discussion must go into greater detail than this post. Some groups optimistically believe that a colonization mission could take place as early as 2020, but such a mindset is dangerous with the lack of long-term information that currently exists regarding habitat construction and functionality. While it is incredibly difficult to address all of the important issues on Earth due to the differences in gravity, one significant current concern is that most of these manageable issues are not being properly addressed in Earth based “Martian simulations”. It seems that most of these simulations are concerned with only addressing one or two elements, if any at all, which could be a mistake because results derived from these simulations may be significantly impacted by creating inappropriate control conditions, which will not be seen on Mars, especially in food supply/growth. Theory should always be addressed rationally; it would be very helpful for further consideration of Martian colonization strategies if simulation studies were designed to incorporate more Martian-like characteristics. Numerous questions still remain, but addressing these simulation issues would be a significant positive step in creating a more accurate simulation experience and developing better preparatory information concerning a Mars colonization mission.

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