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.

Global Political Questions associated with Building a Space Elevator

The idea of a space elevator has long captivated various minds since it was both theorized in scientific circles by Konstantin Tsiolkovsky and introduced into popular culture by Arthur C. Clarke. This fascination is divided between the technical difficulties associated with its construction and the optimistic returns from its successful operation. The most prominent benefit of a space elevator is the presumed dramatic lower launch costs as travel into space would move from expensive single-use launch systems to the multi-use consistent space elevator. Some have attempted to dampen the optimism associated with a functioning space elevator by suggesting that a space elevator in general will not significantly affect the overall cost of space travel.

These suggestions are more than likely incorrect because they commonly fail to appreciate the eventual evolution of a space elevator for the first prototype for any form of new technology is always the most expensive and least efficient. Also the non-launch elements associated with space travel, that skeptics reference as a significant cost factor unaffected by a space elevator, should also see significant cost drops over time, through not immediately, as industries adjust to space travel being a more common occurrence than less than once per year. Therefore, those industries directly related to space travel, especially those that supply parts and consumables, will create more streamlined procedures to prepare for and supply launches. Costs will also reduce through the interaction between the private sector and the public sector as with lower costs associated with space travel governments will be more willing to fund space travel increasing the rate of private funding. Finally a space elevator should be an important achievement for humanity in general if it wishes to actually leave the confides of Earth to colonize other heavily bodies, be them planets, moons, asteroids, etc, with any level of success.

While a lot of effort has been spent on the technical issues and the back and forth of how valuable a space elevator will be, very little time has been spent on the political and secondary economical issues associated with a space elevator. This lack of attention is unfortunate because these issues are very important to the stability of a space elevator both physically and functionality. Therefore, it is important to understand these issues and how they can be successfully managed in order to effectively influence the positive operation of a space elevator after its construction.

The most talked about and analyzed secondary issue with a space elevator is protecting it from environmental damage. The list of possible threats to a space elevator is rather extensive including, but not limited to: lightning and high winds, oxygen and other atmospheric (both lower and higher) chemical reactions, radiation and electromagnetic fields, and space debris along with micro-meteors and other low-Earth orbiting objects like satellites. Concerning satellites it is expected that twice per day each orbital plane will intersect with the elevator and there will be times when both a satellite and the elevator will fill the same area at the same time threatening a collision that will damage both the satellite and the elevator. This problem is not viewed as critical in any real light because operating satellites commonly have a means to generate slight course corrections that can be used to avoid these potential collisions. Non-operational satellites and other space debris are more complicated for they cannot make any adjustments.

Meteoroids, especially micrometeorites, are even worse than space debris for they are much less predictable. Impacts from micrometeorites are almost guaranteed, forcing one of three possible strategies: 1) deploying some form of shielding that could be absorb the damage and then regenerate itself some how; 2) designing a different system for elevator continuity beyond the more conventional ribbon design. One example that has been discussed is the hoytether system, which involves a network of strands in either cylindrical or planar arrangement with multiple helical strands; 3) create an autonomous repair system to manage the various points of damage.

One common and almost universally agreed upon strategy for minimizing the damage potential from orbiting objects is to anchor the space elevator on a mobile controllable target like a large ship or ocean-going platform. By making the anchor point mobile, it should be easier to avoid negative weather patterns as well as non-controllable orbiting objects. Most want this platform in the Eastern Pacific Ocean due to its relatively calm winds and the low probability of lightning. Using non-conductive fibers and small cross-sectional areas that rotate with the wind can provide additional protection. Issues associated with ice formation have been a little more troublesome due to weight considerations. However, all told there may be some meaningful problems with this moving anchor strategy that are not discussed by its proponents, which will be highlighted later.

There is some question to whether or not oxygen corrosion in the upper atmosphere will actually be a significant problem. One way to test the problem potential of oxygen corrosion could be to send various potential elevator material to the International Space Station and expose those materials to the appropriate conditions for extended periods of time. If corrosion is a problem then either the tether must be made from corrosion resistant material like gold or platinum or be coated with such a material. Finally actual repairs to the space elevator are somewhat ambiguous with space elevator supporters simply reporting that there will be special repair climbers that handle this issue. However, it does not lend much confidence when it simply must be assumed that once construction is completed sufficient knowledge will exist to design these repair climbers.

Overall the previously mentioned issues may be the easiest ones when dealing with a space elevator. Very little work has been done on the political issues associated with the operation of a space elevator. For example suppose country A builds a space elevator, what would be the procedure for allowing another country, group or individual to launch something into space? Will the only requirement be the ability to pay some monetary sum established by country A? If so, would that allow a group like Hamas or ISIS to launch something into space?

These are important questions for multiple reasons, but most notably pertaining to potential weaponization of space. Note that for the purpose of this discussion the term “weaponization of space” will mean: “the placement of a device in orbit that can directly destroy, damage or
disrupt the normal functioning of one or more objects within the confines of Earth.” Some individuals would argue that space has already been “militarized” due to the use of satellites in military operations, but space has yet to be “weaponized”. Also note that this definition for “weaponization of space” does not include attacks against orbiting objects like satellites for such potential already exists, demonstrated by U.S. and China and thought to be had by Russia as well.

International agreements concerning space have been far and few between and are commonly negotiated in the United Nations. The first agreement and still governing one, due to actual ratification, regarding international relations within space is the Outer Space Treaty created in 1966 and officially signed by the United States, United Kingdom and Soviet Union in 1967 followed by all other major space “powers”. Unfortunately the Outer Space Treaty only notes broad legalities in association with space like no national appropriation through claims of sovereignty, state responsibility and liability for actions in space or damage, peaceful intent in interaction with celestial bodies, etc. While placing nuclear weapons in space is explicitly forbidden, there is no explicit prohibition of other types of weapons.

More extensive and specific attempts for an international agreement regarding the issue of weaponizing space have been put forward, most notably the two versions of the “Treaty on Prevention of the Placement of Weapons in Outer Space and of the Threat or Use of Force against Outer Space Objects” (PPWT) by Russia and China, but the United States has rebuffed these attempts citing security concerns over possible space assets, a lack of a verification regime and provisions that would directly prohibit possessing, testing and stockpiling weapons that could be placed in outer space. One might questions the validity behind the rationality of this rejection, especially the issue of space assets due to Article V of the PPWT explicitly granting no restriction on the right of self-defense in accordance with Article 51 of the Charter of the United Nations.

Nevertheless the General Assembly of the United Nations has passed two resolutions regarding the prevention of arms in space. The first resolution called on all States to contribute to the peaceful use of outer space, prevent arms races there and refrain from actions contrary to this major objective; it passed with overwhelming support with only two abstentions (Israel and the United States). The second resolution called for the “no first placement of weapons in outer space” and had less support, despite passing, with 4 countries (Georgia, Israel, Ukraine and the United States) voting against and 46 abstentions (including European Union member states). The use of the United Nations as a go-between may need to end in favor of more direct multi-national treaties due to the general lack of respect various powerful countries show the United Nations when it takes a position opposite to that of a particular powerful country as shown in the voting results on these two resolutions.

Also if an agreement is reached what would be the consequences for violating the agreement as all of the countries that could successfully build a functional space elevator have dubious foreign policy histories; thus what penalties could be levied that could reaffirm trust issues in an attempt to normalize relations if such an agreement were violated? Would the only appropriate penalty be the destruction of the space elevator or would operational control be transferred to another party? Should the idea of a treaty be scrubbed completely instead granting operational control of any space elevator to, ironically the most neutral available body, the United Nations? While such a possibility could manage future problems better, how would funding a space elevator proceed if the government of country A knew that it would not retain operational control despite providing the capital, labor and technology to construct it?

Apart from the issues of weaponizing space, the country that controls a space elevator will have an insurmountable economic advantage for launching objects into space, what would happen if this country monopolizes the technology not allowing any other nations access? Can a space elevator simply be treated as any run-of-the-mill commodity? Would anti-trust or global monopoly laws be applied? Should there be an international treaty that sets a firm price for all nations in the event of a space elevator being constructed or should the constructing country have the ability to set any price? These above issues are rarely, if ever, addressed when individuals discuss a future environment with a functional space elevator. The general mindset appears to be a “utopia-esk” societal arrangement where anyone who wants to use the space elevator can use it at cost. Clearly it is difficult to envision this particular environment as one that will develop in reality.

Managing the problems associated with a privately constructed space elevator could also be complicated. Referencing the previous major question of who would have access to the space elevator, suppose corporation A built a space elevator, what would stop them from allowing groups to use it that held political, economical and/or military beliefs that differed from those held by country A? Numerous corporations have demonstrated numerous times over the years that as long as enough money is involved they have no moral qualms against carrying out business relationships with individuals or groups that commonly engage in violent actions against other parties, even if the reasons are superficial. So what types of laws will manage private space elevators? Should it even been legal for a private corporation to have operating control over a space elevator with the severity of what could result from “bad behavior”? Once again should the United Nations take over operating control of the space elevator with all revenue going to corporation A?

With all of the above issues, if any individual or group wants to take the possible construction of a space elevator seriously then the international community must establish guidelines, rules and agreements that address these issues, especially on the issue of access. Access is the most important element because it will establish the general expectations regarding how society will utilize the space elevator to evolve both in a positive or negative manner. Without a binding and known understanding when it comes to these above issues, the probability for the successful construction of a space elevator drops dramatically because uncertainty will more than likely cause some party with the capacity to engage against the construction process in a negative way. Basically if country A does not know whether or not they will get access to a space elevator they may utilize violence to ensure the elevator is never completed.

The issue of potential violence speaks to the location of the space elevator. As noted earlier one of the more popular strategies associated with locating a space elevator is placing it on a movable anchor, most likely a ship out in the Pacific Ocean. What type of protection should this ship have to ensure the safety of the elevator? Would this ship need to house and feed a police force? Would this ship need some form of anti-aircraft defense system? What type of no-fly zone and no-sail zone, if any, would encompass the ship? While the placement of the ship in international waters would eliminating any direct issues of jurisdiction with a single country it would also eliminate a number of problems associated with launching an attack against the ship as well, for attacking a ship in sovereign waters may represent an act of war that would prevent some parties from actually launching an attack. How maneuverable would the ship be if it has to engage in combat for sharp movements may create shearing and tensile stresses on the elevator causing meaningful damage?

Another issue that must be addressed in association with a space elevator is how to manage space debris. The successful operation of a space elevator could dramatically increase the number of objects in LEO or even GEO, which will increase demands on available orbital space as well as provide additional threats to damaging the space elevator. What type of international accord will govern the procedure for managing space debris?

The most significant authority regarding space debris is Article VIII of the Outer Space Treaty which states that all countries retain their ownership rights on all objects launched into space even if those objects are no longer functioning or are pieces off of existing functional objects and the 1972 Convention on International Liability for Damage Caused by Space Objects. There is no salvage aspect to space objects, unlike oceanic objects, which are covered by maritime law. Thus for any country or agency to interact with non-functional satellite A they need legal consent from the launching nation. The biggest problem with this current standing is that small objects that break off of a satellite or other larger space object with no functionality at all are still considered owned by the launching nation, thus technically to remove these objects there origin source would have to be identified making legal removal difficult.

One way to deal with this issue is for all “space” nations to reverse the legal standing of space objects. Basically instead of country A retaining legal standing over all launched material and its resultant components, country A would need to explicitly state what space objects they hold legal standing on, thus if no chain of custody could be established for a given object then no country could have claim on that object and it could be freely removed by an appropriate party.

The two most common removal methods for space debris are: 1) moving the object to a “graveyard” orbit where it will be unable to interact with functioning satellites; 2) launching a projectile at the object to remove it from orbit and return it to Earth. An operational space elevator would ease the obstacles associated with these two above methods as well as possibly provide a third removal method involving attaching the object to a climber and transporting it down to Earth on the elevator itself.

It is also worth noting that Article VII of the Outer Space Treaty covers liabilities; strict liability standards exist for space objects that cause damage to the surface of the Earth or aircraft and fault standards are assigned for damage occurring to a non-Earth based location. This liability would have to be transferred to any organization responsible for removing these objects. Unfortunately for those desiring a competitive marketplace for debris removal, the best strategy would actually be limiting all removal activities to the controlling operator of the space elevator due to this group possessing the most relevant knowledge and access. Competitors would not have access to the elevator and their strategies for removal would typically be more risky. Flat and fair rates should be charged for debris removal.

Due to the increased ease at removing debris, would it be appropriate for each country to replace all satellites older than x years (x to be determined by an international agreement) including all associated parts at cost before allowing the use of the space elevator? Basically with the development of a space elevator would countries be able to launch as much as they could afford or would each country have a specific quota based on the some factor (size of economy maybe) that could even be brought/sold/traded?

Overall there are a number of important political and diplomatic issues that have yet to be discussed let alone resolved regarding the construction of a space elevator. One might suggest that discussing these issues is akin to putting the cart before the horse for the technology to construct a space elevator is still in its basic infancy; however, that fact highlights the necessity of discussing these issues for if these issues cannot be successfully managed and resolved then the construction of a space elevator would produce wasted effort and resources. Managing the political issues go hand in hand with the technical issues for successfully operating a space elevator, so it is important that all aspects of a space elevator be discussing in realistic terms over some dreamy utopic ideal.

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 –

1. Drew, K, et Al. “Central nervous system regulation of mammalian hibernation: implications for metabolic suppression and ischemia tolerance.” J Neurochem. 2007. 102(6): 1713–1726.

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.

A Brief Discussion Regarding Feeding Future Martian Colonist

Colonizing Mars will be a significant endeavor with many moving parts and critical decisions to make. One of the most important decisions is how to design the appropriate food supplementary methodology for the colonists as Martian environmental conditions differ significantly from Earth. This difference demands a clear and transparent strategy to ensure the safety and productivity of future colonists. Fortunately there is sufficient predictability and routine with regards to creating this food production strategy making it easier to compare and contrast competing options.

The first element to understanding the dietary requirements for Martian colonists is deducing the minimum requirements for survival on Earth. The typical energy recommendations for a sedentary individual approximately 70 kg are about 2,000 calories, which should be familiar to most individuals because it is the basis of daily recommended allowances for nutrients used by the FDA. There is the argument that more active individuals will require double that at 4,000 to 4,500 calories. Some reference that most astronauts involved in the Apollo missions consumed an average of 2,793 calories, but their missions were extremely short (less than a week).

A more apt reference comes from Biosphere 2 where participants consumed 2,216 calories per day, but even at these consumption levels participants lost an average of 8.8 kg over the 2-year experiment. Unfortunately it stands to reason that Martian colonists will be more active than Biosphere 2 participants due to required frequent extra-vehicular activities (EVAs) to construct additional elements to expand the initial habitat and scientific exploration. Also there is little information regarding how nutrition needs and absorption capacity change in a low gravity environment, especially with regards to gut bacteria.

Another problem is that these calories need to include the 9 essential amino acids for healthy adults: phenylalanine, valine, threonine, tryptophan, methionine, leucine, isoleucine, lysine, and
histidine. Studies on a minimal diet required for survival included 10 different foods: soybean, peanut, wheat, rice, potato, carrot, chard, cabbage, lettuce and tomato with recommendations for additional nutrients from sugar beets, broccoli, various berries, onions and corn.1 Unfortunately it is unlikely that such a wide array of foods will be available for a Mars colonization mission past the food that initially travels with the colonists. In addition early on in the expedition colonists will have to eat additional food brought from Earth to compensate the lack of sufficient growth on Mars.

However, the weight and cost of carrying a large amount of food with the colonists could be crippling. A general estimate can be made using MRE information. Each MRE contains about 1,200 calories.2 A colonist would consume at least two MREs per day. The general average weight of an MRE is estimated at 635 grams or slightly under 1.4 pounds.2 Therefore, the average weight of food for a day per colonist is 2.8 pounds. The generic cost associated with launching something into space is 8,000 – 10,000 dollars per kilogram (i.e. 3,636 – 4,545 dollars per pound), thus 3.716 million to 4.645 million dollars per colonist per year in food costs. Some could argue that this price is lower due to the activities of Space-X, but most people forget that these estimates are not made to scale. There is a big difference between $2,000 per pound when launching 2,000 pounds and $2,000 per pound when launching 200,000 pounds. Also any estimate can be made depending on how much money a company is willing to lose on a launch. Unfortunately cost is not the only limiting factor for colonists bringing their own food.

Some could argue that the nutrients provided by some of these foods can be substituted through vitamin consumption, but there are lingering questions about nutrient absorption when vitamins are principally responsible for nutrition. Another more minor concern revolves around shelf life for freeze-dried and MRE-type packaging, which will limit the use of initially sent food to a maximum of approximately 2 years. As stated above this concern should not be significant because greater than average food consumption will be expected due to activity levels and a lack of grown food. Finally for some there is the continuing pseudo concern of unappetizing food in space due to the specific cooking and harvesting techniques required for reduced gravity environments. This concern is rather meaningless because if someone has the choice between eating something boring, repetitive and unappetizing or dying, any sane individual will select the first option.

Based on the anticipated workload and a difficult living environment (pressurized homes and bulky pressurized spacesuits) all settlers on Mars will require additional calories beyond average consumption levels. While freeze-dried food shipments can be delivered periodically from Earth the costs associated with such missions, as estimated above, should prohibit executing this strategy indefinitely. Overall the reality is that some form of food synthesis/production methodology needs to be created for Martian colonists.

Obviously growing food on Mars will be difficult because the lack of quality soil, rainfall and consistent sunlight will force all growth to occur indoors in a pressurized environment under artificial light in a hydroponic or aeroponic infrastructure. The advantages to using soil versus a nutrient baths are numerous including, but not limited to: 1) soil playing a significant role in air purification; 2) acting as a central and low energy recycling and composting system for various types of waste; 3) difficulty re-supplying nutrient solutions away from Earth potentially limiting the lifespan of a hydroponic or aeroponic system; 4) increased gaseous aeration and reduced water leaching in the presence of no toxic agents due to the gravity difference.

Clearly somehow incorporating soil would be a large boon to the colonization process. Some individuals have very optimistic notions that the soil can be rehabilitated to the point where it can support food growth. Some initial experiments argue that it is possible to grow food in Martian soil.3 However, this research has its concerns in that the soil used to emulate the Martian soil was free of contaminants along with a lack of pressure and gravitational changes inherent to Mars, thus perceiving these results as accurate to cultivation on Mars is irresponsible. A rehabilitation process will take years, if not decades, and more than likely will not start until after colonists have made landfall.

The problems with this rehabilitation process are as followed: 1) high concentrations of detrimental agents including various salts, oxides and toxins, especially chlorine and aluminum; 2) impurities heavily reduce water uptake efficiency, which due to the lack of available water on Mars would dramatically reduce yields; 3) a theoretical lack of ability to support continuous microorganism growth which is essential for quality soil health; 4) a lack of important secondary nutrients that foster plant growth like boron and molybdenum; 5) pH of regolith soil can vary from place to place, similar to Earth, but the variations on Mars are more radical. pH will be very low in places with large amounts of jarosite and very high in places with large amounts of NaHCO3 and Na2CO3. Neutralization of these high acidic or basic regions would require large amounts of CaCO3 or olivine deposits and peat moss respectively. 6) A direct lack of principle nutritional agents most notably nitrogen and phosphorus. Some argue that nitrogen can be created through weathering, a process that will take far too long, or nitrogen fixation through various microorganisms, a process that is questionable due to existing soil conditions and a lack of phosphorus. Phosphorus only seems available through fertilizers and also requires leaching CaSO4 deposits to avoid phosphorus interaction before plant absorption. Therefore, it is unreasonable to assume outdoor food growth for the first few decades.

Some have argued that even if the Martian soil cannot be utilized the Martian atmosphere could be due to its high CO2 percentage. While approximately 95% of the Martian atmosphere is CO2, the total concentration of CO2 is much smaller than the concentration of CO2 in Earth’s atmosphere because the Martian atmosphere is dramatically thinner. Therefore, on its face there is not enough CO2 available to allow free flow of air from the Martian atmosphere to produce a net benefit in plant growth. Even if CO2 concentrations were large enough the frequent dust storms with additional regolith deposits would cause significant problems for the free airflow greenhouse and it would be incredibly difficult to filter these elements due to their very small particle size. So currently it stands to reason that all food growth in a Martian colony for the first few decades will require complete isolation from native Martian conditions.

With the lack of viable soil the most popular strategies for growing food on Mars have been to forego soil use altogether and use hydroponics. Hydroponics eliminates the soil issue, but it raises its own concerns regarding water use and nutrient supplement. 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. While some hydroponic proponents report that hydroponics actually save water, these assertions are born from a comparison between hydroponic use and flood irrigation in traditional fields rather than drip irrigation. When compared against drip irrigation, hydroponics results in slightly greater water use. 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 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 are 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.4 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. Note the lack of experimentation for such a system on Earth. None of the numerous “Martian Simulation” experiments 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?

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. 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.5 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 or its own future constructed habitat completely isolated from the principle habitat.

One final note when deciding between hydroponics and aeroponics is the issue of yield vs. available space. If an aeroponic system is properly designed it can maximize space utilization of the habitat module by using walls and ceilings. A hydroponic unit will have to compete for space that could be utilized for storage, manufacturing, sleep, leisure, etc. Alleviating this potential space problem would involve sending to habitation modules to Mars where one would act as the living unit and one would act as the farming unit devoted to hydroponic use. While clearly the costs of such a plan would be significant due to weight issues, success would allow for special oxygen/CO2 customization of the farming unit, which would reduce the complexities of isolating the farming and living units in the same habitation module. This farming unit could also be constructed on Mars using in situ resources to avoid weight based travel complications.

When addressing the food itself, while it would be ideal to grow a wide selection of fruits, vegetables, nuts, etc. to increase moral through variety of food choice, for the first group of colonists the lack of viable Martian soil converts space into the limiting factor with water close behind. Therefore, it is important to identify the foods that give the best “bang for the vitamin buck” with regards to growth space. As mentioned early on most foods that will be grown on site will require either hydroponics or aeroponics, thus growth method combined with space considerations will make it difficult to grow various vining plants like tomatoes, cucumbers, peas, grapes, etc. Also large surface area or volume crops like corn, squash, melon, zucchini, etc. would be ill advised. Due to the additional energy requirements for colonists, especially those actively searching or building on Mars, a large source of complex carbohydrates should be grown. There are numerous quality candidates for carbohydrates namely cassavas, soybean, sweet potatoes and lentils.

Of the possible carbohydrate options the cassava root is an attractive one. One of the principle advantages to the cassava is that it is significantly drought tolerant and capable of growing well in sub-optimal soils. Clearly these elements are advantageous in a water uncertain environment like Mars where any water savings that can be created is a benefit and a non-optimal nutrient mix could become the norm. There are two types of cassava, sweet or bitter and while bitter is preferred on Earth due to its enhanced pest deterrence, the lack of these organisms on Mars would make sweet a better choice for a more appetizing meal. The purpose of growing cassavas is to harvest the root, thus the leaves of the plant can be pruned early in its growth cycle to limit space use. However, if insects are also being cultivated, the leaves can be harvested as a secondary food source. The roots are good sources of calcium and phosphorus, which are critical elements for bone structure, as well as vitamin C.

In contrast to cassavas, sweet potatoes are more finicky in their growth requiring lots of light and warm temperatures (70-80 degrees F) along with significantly more water. Most varieties of sweet potatoes have some vining characteristics, which could create space issues, but there are bush-type varieties that should be used instead. Due to near immediate consumption sweet potatoes grown on Mars will not be cured eliminating that processing step. Sweet potatoes provide significant concentrations of fiber, beta-carotene, calcium, phosphorus and vitamin A. Overall it seems reasonable that there would be a competition between either using sweet potatoes or cassava with cassava having more overall nutrients and sweet potatoes having better flavor and concentration of certain nutrients like vitamin A.

Lentils are an edible pulse of the legume family and are widely grown throughout the world for its high protein and general nutritional content. Lentils contain essential amino acids phenylalanine, valine, threonine, tryptophan, leucine, isoleucine, lysine and histidine, lacking only methionine. Some report that sprouted lentils contain methionine.6 In addition to the large essential amino acid complement, lentils also have significant amounts of fiber, folate, iron and vitamin B1. However, while lentils have a wide variety of essential nutrients their preparation is more complicated than most foods requiring long-term soaking in warm water to reduce phytate and trypsin inhibitor content. This additional use of water beyond simple rinsing may give pause to the use of lentils as a food source in the initial stages of a Mars mission.

Another quality option outside the starchier ones above is broccoli. Broccoli is high in fiber, vitamin C, vitamin B2, Pantothenic acid (B5), vitamin B6, folate (B9), manganese and phosphorus along with numerous alleged anti-cancer and immune regulatory molecules like selenium and diinodlylmethane. A secondary advantage, beyond the high nutrient value, is that broccoli is resilient, grows quickly and is harvested easily. The one possible concern for broccoli is the total area of the leaves can become large, but these leaves can be pruned to eliminate this concern. Currently there is little reason to exclude broccoli from the food options for Martian colonists.

Soybeans are commonly considered a quality choice for Martian food because they are a source of complete protein (a food that contains significant amounts of all essential amino acids) in addition to it being a quality source of protein. However, there are some concerns. First, similar to lentils above soybeans must be cooked with “wet” heat to destroy trypsin inhibitors, which will take time and additional water resources. Second, modern cultivars typically reach a mature height of 3-3.5 feet, which could create space concerns depending on where the soybean crop is planted, especially for hydroponic strategies. If soybeans were grown, pruning would more than likely be required.

Keeping with the theme of green vegetables, spinach is another quality option. Rich in lutein (for the eyes), vitamins A, C, E, K, B2, B6, magnesium, manganese, folate, betaine, iron, calcium and phosphorus. It is also a quality source of folic acid, which has been in rather short supply for the other candidates mentioned so far. Also the inclusion of peanuts could be an interesting possibility. Peanuts are high in fiber, folate, niacin (B3), phosphorus, vitamin E and magnesium along with large concentrations of protein, much more than can be acquired from fruit and vegetable candidates. Some may argue that growing peanuts hydroponically is difficult because of the burrowing flower stem; however, peanut blossoms have successfully buried themselves in nutrient media and formed viable peanuts. Therefore, there is nothing to be concerned about under normal conditions, whether or not Martian gravity changes that is unknown.

A brief note regarding genetic engineered crops. There are two schools of thought regarding the inclusion of these types of crops. Proponents would argue that it is advantageous to genetically engineer all of the seeds that colonists bring with them to Mars for drought resistance, additional vitamin synthesis (i.e. Vitamin A in golden rice) and maximum photosynthetic efficiency. Due to the use of hydroponics each plant can be semi-isolated restricting the possibility of cross contamination if something goes wrong. Opponents would argue that this isolation is rudimentary and that if something were to go wrong from a genetic standpoint then the colonists would be put at severe risk depending entirely on food from Earth. Logically it makes sense for colonists to avoid homogeneity by having a variety of seed types some that have been engineered and others that have not and plant accordingly.

This combination of plant products does not, however, completely meet all nutritional requirements, as it is low in sodium and lacks animal origin vitamins and fat such as B12 and cholesterols. This is a common feature of plant-based diets. To overcome these deficiencies sodium can be supplied in mineral form. If one concluded that the use of plant based protein sources is unreasonable due to a lack of overall content, then additional sources of protein will have to be acquired elsewhere. Utilization of large animal based protein like cows and chickens is unreasonable due to the resource demands, thus insects and fish are appropriate animal food sources in a space agro-ecosystem, given the limited area available for their rearing and for efficient use of other resources to fill the nutritional requirements.

Muscular atrophy in a reduced gravity environment is a running problem. Skeletal muscle principally involved in maintaining proper posture are most negatively affected by the reduction of gravity because this muscle has evolved to balance an environment where gravitational forces are 9.8 m/s^2. That said it appears that slow twitch muscle fibers are more susceptible to the change in gravitational force versus fast twitch muscle fibers.7,8 This difference in degradation can be troublesome because not only are slow twitch associated with posture, but are 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.9-11 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. Therefore, in order for colonists to increase the probability of limiting apoptosis a constant supply of protein will be required.

One of the key advantages to utilizing insects is that they can be fed on substances that are inedible for humans yet are byproducts from other processes. For example two of the most promising insect candidates are the silkworm (Bobyx mori) and common termites because they survive on mulberry leafs and cellulose or lignin respectively. The silkworm is the better choice of these two because it cannot escape its rearing room to become a nuisance to the colonists, it produces a useful byproduct in its silk cocoon, and colonists can consume a part of its principle food source (the berries from the mulberry plant). Termites are popular for those who plan to incorporate wood into colony construction, a strategy that does not appear to be effective in its versatility or overall usefulness. Therefore, with the obvious advantages of silkworms as both a protein source and secondary material source it stands to reason that all insect rearing should focus on silkworms.

Additional protein sources can be created through aquaculture fostering suitable concentrations of small fish. It is not reasonable to expect ideal water quality in the aquaculture, thus the selected fish must be able to effectively survive during periods of high toxicity or salinity. In addition the fish must have a small maximum growth potential to avoid resource over-consumption due to overcrowding. Understandably in most situations fish harvesting would occur often enough that overcrowding should not be an issue, but overall it pays to be careful. With these two conditions in mind the two best fish candidates appear to be loach and tilapia due to their abilities to resist negative environmental elements like poor water quality, high salt concentrations and limited water availability.

Another option for a more advanced colony is to develop an aquaponic system. In such a system plants are grown in a way where their roots are immersed in the nutrient-rich effluent water of an aquaculture. The plants should filter ammonia and other toxic metabolites that could damage the aquatic life. The water is then reintroduced to the aquaculture water pool. There are many different types of aquaponic systems, but deep-water raft seems to be the best for Mars due to its simplicity, low power requirements and greater flexibility with germination staggering because different plants have different rates of growth.

Some also argue that including algae, either hydroponically or aquaponically, should be a boon to food production. One of the most powerful reasons to include algae is that it can form a closed ecological cycle. Add the algae to an environment with water, CO2, and energy (light source) and such a system can theoretically keep a person supplied with food and oxygen for as long as the system is maintained.

For some individuals Spirulina (a type of algae) is thought to be an ideal health food and some hope that these positive traits can be maintained as a food for Martian colonists. The inherent advantages of spirulina are that it is easy to digest due to a lack of cellulose, it contains a large number of vitamins sans vitamin C and eight of nine essential amino acids, and produces a high protein by weight percentage (55-65%). However, there are some drawbacks as well most notably it ability to effectively absorb environmental elements like radiation and heavy metals including producing anatoxin as well as producing large concentrations of nucleic acids which can lead to gout if more than 50 grams are consumed in a day. In addition it has an unappetizing green slime texture and taste. While that last negative should not matter in a survival situation, from a psychological standpoint there exists a high probability that eating Spirulina day after day after day will have a negative effect.

Apart from preparing an appropriate area to grow food and selecting what should be grown, a strategy to manage produced organic waste from both humans and plant matter needs to be developed. Unfortunately there is a significant limitation in possible strategies due to a lack of available oxygen on Mars. This lack of oxygen reduces the effectiveness of traditional composting making it difficult to select as a viable strategy. Some argue that the use of Geobacter, an anaerobic respiration bacterial species, which can oxidize organic substances using iron oxides and can even generate electricity as a byproduct. However, while iron oxides are available on Mars their extraction requires work either human or machine, which adds an additional element to colonization.

Some have argued for the inclusion of hyper-thermophilic bacteria may be the best option for eliminating organic waste in an 80-100 degree C environment.12 Basically the colonists utilize a small autoclave with these bacteria resulting in organic decomposition and the elimination of harmful organisms that may reside in the waste. In addition the waste heat from the autoclave process can be released into the living environment to reduce electricity demand over a short period of time or for distilling water. However, the problem with this strategy is the oxygen requirement. For a long period of time on Mars oxygen should be in short supply, thus transferring some oxygen for waste removal processes may not be prudent. Overall the best strategy appears to be using Geobacter as a principle source of waste elimination.

In the end it is important for Mars simulation experiments on Earth to study the initial best food choices to determine how they would grow in similar conditions sans gravity changes. Unfortunately current food consumption methodologies in these simulation experiments are too well developed. While 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), this initial source food will be consumed over a period of time (1-2 years) and less hardy choices will be relied upon for a significant time period afterwards. 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.

The next Mars simulation study should only bring a small amount of food and focus on attempting to successfully grow broccoli, peanuts, sweet potatoes, soybeans and spinach in Mars like conditions using hydroponic and aeroponic systems. The type of information born from this experiment is much more important to a successful Mars colonization mission than the simple isolation/psychological experiments because those selected for Mars will be able to handle the psychological aspects of the colonization, but they will not be able to handle starving to the point of death.

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Citations –

1. Hender, Matthew. “Colonization: a permanent habitat for the colonization of Mars.” 2010. http://digital.library.adelaide.edu.au/dspace/handle/2440/61315

2. Wikipedia Entry Meal, Ready-to-Eat (MRE);

3. Wieten, Jesse. “Dutch researcher says Earth food plants able to grow on Mars” Mars Daily. Jan 21, 2014. http://www.marsdaily.com/reports/Dutch_researcher_says_Earth_food_plants_able_to_grow_on_Mars_999.html

4. Clawson, James Sr. Aeroponics.com. January 1, 2012. http://www.aeroponics.com/aero43.htm

5. Kim, H, et Al. “Green-light supplement for enhanced lettuce growth under red and blue-light emitting diodes.” HortScience. 2004. 39(7). 1617-1622.

6. Wikipedia Entry – Lentil

7. 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.

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

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

10. 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.

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

12. Kanazawa, S, et Al. “Space agriculture for habitation on Mars with hyper-thermophilic aerobic composting bacteria.” Space Agriculture Task Force.