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.

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.



==
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.
==
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.