Ender Space Settlement Design Contest. 2014-2015 Kelly DeRees David Sugg Special Note

5.1 Classification of Utilities

To understand later the economic and societal impacts of the infrastructure described in this section, the term “utilities” must be carefully defined. “Utilities” in this paper refers to water and electricity only.

Ender will not have natural gas due to its safety issues and difficulty to acquire and store. Natural gas, as the name implies, is a gas at room temperature. On Earth, underground pipes carry natural gas to homes. Because of the Earth’s size and voluminous atmosphere, a natural gas release can be handled relatively easily by the natural movement of the atmosphere. On Ender, however, a natural gas release or other accident could be devastating to the colony. First, with a closed, recirculating atmosphere, a gas release would be nearly impossible to fix because methane is difficult to scrub from the air (methane scrubbing technology is still in its earliest stages and is not ready to implement). Air circulation systems could circulate the gas through a large portion of the station before segments could be closed off to quarantine the gas. Second, because of the flammable nature of natural gas, a gas release would pose a serious fire safety issue.

Another safety issue is storage. To maximize the amount of natural gas stored on Ender, it would have to be stored as a cryogenic liquid, which poses unique dangers. A liquefied gas is highly explosive, and the extremely cold temperatures are dangerous and difficult to maintain. The same issue arises when attempting to transport natural gas. It is inefficient to transport a substance as a gas because of the space it occupies, so liquefied natural gas would be necessary for transportation. Because there is no source of natural gas aboard Ender like there is on Earth, all gas would have to be transported from Earth or fracked from other planets. Transportation would require launch, which would be incredibly dangerous due to the high temperatures of the explosive fuel combined with the stored cryogenic natural gas.

The expense and danger of transporting and storing natural gas rules it out as a viable utility aboard Ender. Therefore, the only services implied by the word “utilities” include water and electricity.

5.2 Plumbing and water treatment

5.2.1: Section 1 – Domestic and Commercial Plumbing

A water main will carry water from a central water treatment plant to the rest of the colony. For the four residential sections of Ender, a water main will run along the outer perimeter of each section (note: the water main will not be outside the spacecraft; it will be placed on the interior of the spacecraft on the outer wall). The water main will branch into smaller pipes, which will carry water into the residential pods for individuals and families to use. Normal features such as kitchen and bathroom sinks, toilets, and showers are expected in the residential pods. To handle waste water from the residential sections, a separate piping system to return waste water to the water treatment plant will run parallel to the water main.

A nearly identical system will be implemented in the business/industry ring. The only difference will be that the inner ring is a complete circle, not split into sections like the residential ring.

5.2.2: Section 2 – Agricultural Plumbing

For the agriculture ring, a different system will be used. As with the residential and business rings, a water main will run along the outer circumference of the ring. The agricultural water main will be larger to accommodate the massive amounts of water necessary for agriculture. For soil irrigation, perforated pipes (pipes with small holes in them) will be placed beneath the soil. Unlike an agricultural sprinkler one might find on Earth, which sprays water into the air and relies on gravity to pull the water into the soil, the water on Ender will be distributed directly to the roots of the plants. By applying water directly to the soil instead of spraying it into the air, water is conserved, saving energy in the water treatment process.

An important part of agriculture is crop rotation; rotating crops protects the soil from exhaustion and preserves the soil’s fertility. However, different crops require different amounts of water. With this irrigation system, crops can be rotated without changing the water infrastructure. The irrigation plumbing will be set up as branching segments of piping. Smaller pipes will branch off from the agricultural water main, and even smaller pipes will branch off of these (much like veins in a leaf). At each joint where new pipes branch off, valves will be available to control the water flow. After crop rotation, the amount of water for each crop can be adjusted (using the valves) to optimal levels so as not to dehydrate or flood a crop with the water setting used before rotation for a different crop.

Another important aspect of agriculture is humidity. To control humidity, small pipes will carry water from the water main into the “roof” of the agricultural ring. These will act as fine mist sprinklers, which will distribute water directly into the air above the plants. These sprinklers are for fine mist only, and will not be used as a source of irrigation for the roots. Rather, the fine mist from the sprinklers will evaporate quickly, humidifying the air to keep the plants healthy. Humidity sensors in the agricultural ring will allow fine tuning of the humidity, so mist will only be used when needed, ensuring efficient use of water.

5.3 Waste Management

To process the waste produced by the daily operations of Ender, a clever waste management system must be utilized. First, the types of waste Ender will produce must be discussed and classified.

5.3.1: Section 1 – Classification of Waste

Daily operations aboard Ender will produce solid metabolic, agricultural, food, water, industrial, medical, and miscellaneous waste. Any solid biological human waste (such as feces) will be classified as solid metabolic waste. Any unused raw product grown in the agricultural ring will be classified as agricultural waste. Unused food will be considered food waste. (Note: The distinction between agricultural and food waste may be very subtle at times. Food waste shall be considered to be any agricultural product that was processed into a food product. Agricultural waste will deal only with the raw materials grown in the agricultural ring.) “Grey water,” or waste water from homes and businesses, as well as urine, will be considered water waste. Any wasted metal or other manufactured product that is not food will be considered industrial waste. Medical waste will contain hazardous biomaterials (biohazards) such as syringes. Miscellaneous waste will be any paper, plastic, or other waste that does not fit into the other categories already described (similar to regular household waste on Earth).

5.3.2: Section 2 – Managing Solid Metabolic Waste (SMW)

To manage the solid metabolic waste (or fecal waste) produced on Ender, there are a few possibilities. The first option is to dispose of the SMW by ejecting it into space on a trajectory that would not interfere with other spacecraft (i.e. out into space, away from Earth). The next option is to use mechanical and chemical process to retrieve the water in the SMW, which would then be treated and recycled aboard Ender. A final possibility is to use the SMW as fertilizer, adding it to compost to enrich the soil (not recommended).

The average human produces about a pound (~0.45 kg) of feces each day (Newcomer, 2012). Multiplied by 10,300 people, this amounts to about 10,300 pounds (4672 kg) of feces per day. Normal stool is ~75% water (Jensen, 1976), meaning that 7,725 pounds (3504 kg) of water is contained within the feces produced daily by the citizens of Ender. If discarded into space, this would amount to a massive waste of water (1,278,960 kg or 338,349 gallons per year [a gallon of water weighs 3.78 kg]). Therefore, simply ejecting the SMW into space is not a good option.

The possibility of using raw SMW as fertilizer raises health concerns due to the bacteria that reside in human fecal matter. Applying SMW to agricultural processes could lead to disease, which is not a risk worth taking aboard a closed system such as Ender.

The other option is to retrieve the water from the SMW through mechanical and chemical processes and further process the remaining solids for use in other applications. Using an innovative new technology, the Janicki OmniProcessor developed by Janicki Bioenergy, SMW can be turned into potable water, electricity, and ash. The Janicki OmniProcessor heats the SMW until the water evaporates. The water vapor is collected and cooled to produce liquid water. The remaining SMW matter (now dry) proceeds to an incinerator, where the steam from burning the matter generates electricity and kills pathogens in the SMW. The only product remaining is ash, which can be used in compost to fertilize the soil in the agricultural ring (Gates, 2015). This system allows for 100% reuse of SMW, eliminating water waste and maximizing the resource efficiency of Ender.

Another benefit of fully recycling the SMW is that there are no solids left over that must be discarded by ejecting them from the spacecraft. This means that there is no danger posed to nearby spacecraft by the frozen fecal matter, which could act as high-speed bullets and damage spacecraft.

5.3.3: Section 3 – Managing Water Waste

To manage urine, a forward osmosis system will be used to remove the water from the urine and use the remaining product to produce a small amount of electricity. Forward osmosis involves using a “concentrated salt or sugar solution to draw the water out of the urine” (Engelhaupt, 2014). Enzymes “convert the leftover urea into ammonia,” which is then used to generate electricity (Engelhaupt, 2014). This system has been implemented on the ISS, and though the technology is still in a somewhat early stage, it has shown promising results and has potential for great improvement. Ender would require a scaled-up version of this system, possibly with many “cells” for efficient operation.

Image from http://www.htiwater.com/technology/forward_osmosis/

One downside to the forward osmosis system is the amount of miscellaneous waste it produces. Forward osmosis requires membranes (as pictured above), which must occasionally be replaced. Depending on the pace of advancement of the forward osmosis technology, processing the vast amounts of urine produced on Ender each day could produce a lot of waste (used membranes). It could be argued, however, that the generation of electricity from the byproducts of forward osmosis might be a benefit that outweighs the drawback of membrane waste. The energy could be utilized at the water treatment plant to power any necessary electrical systems required for the forward osmosis systems, making the net power draw for forward osmosis close to zero.

5.3.4: Section 4 – Toilet Design

To fully understand the waste management systems for SMW and water waste, the toilet design must be addressed. Because Ender must operate independently of Earth, resource management and conservation must be taken very seriously. Therefore, net waste must be minimized. To minimize net waste from human biological functions, the toilet design must be carefully considered. On the International Space Station, the toilet consists of two main parts: a solid waste receptacle and a liquid waste receptacle. The ISS uses suction instead of flushing water and gravity to contain the matter within the receptacles. On Ender, with artificial gravity, small amounts of normal flushing water can be used, but there will still be two main receptacles, as with the ISS. Because the treatment processes for liquids and solids are very different from each other, the liquid and solid waste must be separated for further processing. By separating the two types of waste, net waste will be minimized.

Example of space toilet design. Image from http://pages.erau.edu/~ericksol/projects/futurspcrft/sp/intro.html

5.3.5: Section 5 – Food Waste

The wasted food produced aboard Ender will be ground up and turned into compost for agricultural use. Because residents will be consuming food in their own residential spaces as well as in restaurants and businesses (workplaces), food waste receptacles will be placed in both residential spaces as well as in restaurants. These receptacles will be built in to the structures, similar to a laundry chute. The receptacle will be near the entrance to the residential areas, with a small door to keep any odors from travelling through the residence. The food waste will be collected daily from all residences, restaurants, and businesses. The waste will be taken to the waste management center and ground into a paste, then turned into compost for use in the agricultural ring.

One problem with this system is that the residents might accidentally include a piece of non-compostable waste in their food waste. This problem is unavoidable, so at the waste management center, workers will need to sort out the biggest pieces of non-compostable waste from the food waste before the food is sent to the grinders. In an attempt to minimize the man hours necessary to sift non-compostable waste from food waste, the difference between these two types of waste and the importance of conservation/recycling will be a major part of the curriculum in all levels of education. To supplement the social effort, an incentive program could be implemented, similar to the incentive program in some states to encourage residents to recycle pop cans (for example, in Michigan, every pop can returned to a designated center earns 10 cents).

5.3.6: Section 6 – Agricultural Waste

Most agricultural waste, if not infected by a pathogen, will be recycled as compost for future use in agriculture. If a bacteria, mold (fungus), or virus has infected agricultural waste, the waste will be incinerated and the remains will be discarded into space to prevent the spread of disease between crops.

With the human fecal waste discussed earlier, drying and burning the waste to fully recycle it does not pose any risk of spreading disease because the pathogens found in the material consist of bacteria, not fungus. The bacteria in the fecal waste can be killed, effectively stopping the spread of disease. Agricultural waste, however, possesses a unique danger. Blight, a fungal infection that spreads easily among plants and damages crops, could wipe out Ender’s entire food source if allowed to spread. The spores of the fungi associated with blight, Alternaria solani and Phytophthora infestans, can remain dormant for many years (Western Australia Department of Agriculture and Food). For this reason, any affected plant material should be burned and discarded (Schumann, 2000). Because of the tenacity of Alternaria solani spores, the ash from the burned plants should not be applied to compost. Even just a few remaining spores after incineration could spread infection to many other plants (Schumann, 2000).

An incinerator located in a central waste management center in the business/industry ring of Ender will burn the affected plant material. The ash will be compacted into a block and ejected into space on a trajectory that would not affect nearby spacecraft.

5.3.7: Section 7 – Medical Waste

Medical waste (i.e. used syringes, leftover medical serum, etc.) will be stored in large biohazard vacuum bags. The air will be removed from the bag using a vacuum system located in the central waste management facility on Ender. After compressing the bag by removing the air, the bag will be ejected into space. Rather than try to recover any material in the biohazard bags, the material will be disposed to prevent the spread of disease among Ender’s residents. The possibility of recovering material was considered when designing Ender’s waste management systems, but with 10,300 residents in close quarters aboard Ender, the risk of spreading disease was too great for material recovery to be considered safe. Therefore, biohazardous materials will be discarded.

Note: the term “medical waste,” as discussed in this section, refers to biohazardous materials. Some miscellaneous waste, such as waste paper, will also be produced in daily medical operations and systems, and this waste will be classified as miscellaneous waste rather than medical waste. See Section 9 – Miscellaneous Waste for a description of how miscellaneous waste will be handled.

5.3.8: Section 8 – Industrial Waste

Industrial waste will consist mainly of waste metal from manufacturing procedures. This metal will be sorted and melted to be recycled in further manufacturing procedures. If, for some reason, a metal develops a defect that prevents it from being safely used in manufacturing (and this defect cannot be removed), the metal will be discarded. This situation is unlikely due to the ability to melt the metal and recycle it, but this procedure will be in place if ever the situation arises.

Other industrial waste might consist of defect paper or plastic that is discarded from the paper/plastic manufacturing facilities (meaning it hadn’t yet been implemented as a consumer good). The paper will be shredded and recycled to make new paper products, such as cardboard. The plastic will be melted and recycled to produce new plastic products. As with the metal waste, if a piece of paper or plastic has a fatal flaw that cannot be removed and the material cannot be repurposed, it will be discarded.

5.3.9: Section 9 – Miscellaneous Waste

Any waste that does not fall into the categories discussed earlier will be considered miscellaneous waste. For example, paper and plastic waste would be considered miscellaneous waste. Instead of simply discarding these materials, they will be recycled at the waste management center. Residents will be asked to keep their food and miscellaneous waste separate, and most miscellaneous waste items will be recyclable. A receptacle similar to the food waste receptacle will be installed in each residence, restaurant, and business. The miscellaneous waste will be collected twice a week. The waste will be sorted at the waste management center into paper, plastic, metal, and other. Paper will be ground up and recycled as cardboard or other paper products while plastic is melted and reused in new plastic products. Metal will be sent to the industrial waste section of the waste management center to be melted down and repurposed. The amount of resident-produced metal waste is expected to be low because most consumer goods will be packaged in paper or plastic, reserving metal for manufacturing of infrastructure or other critical purposes. Anything that does not fit into the paper, plastic, or metal categories will be considered “other,” and if no other purpose is found for these items, they will be compressed and discarded.

5.3.9.1: Section 10 - Overview of Waste Management Infrastructure

A facility called the “waste management center” has been referenced several times in discussing the different types of waste and how they will be managed. This center will be located in the business/industry ring of Ender, near the water treatment plant (but not part of the same facility). The waste management center will consist of sorting bins, paper grinders, plastic grinders, and an incinerator press. The three types of grinders are for purposes described in Section 9 – Miscellaneous Waste above. The incinerator press will burn any unusable scraps or infected plant material, then press the ash into a hard block to be discarded. One other feature of the waste management facility will be the medical waste vacuum system, which will vacuum the air out of medical waste bags before discarding the materials. A separate section, adjacent to the main waste management center, will be used for industrial waste. Because multiple manufacturing centers are expected to be aboard Ender, centralizing the industrial waste management system is more efficient than expecting each industrial center to manage its own waste (primarily metal). Similar to the chutes for waste found in residences and businesses, each industrial center will have chutes for metals (a separate chute for each type of metal to avoid confusion in the waste management center). The metal waste will be collected once a week, then melted and reformed into usable material at the waste management center.

5.4 Ventilation and Temperature Control

Because Ender has no natural atmosphere to disperse CO2 and other gases in the air, an artificial ventilation system must be implemented. The massive amount of plants in the agricultural ring will produce oxygen for Ender’s residents to breathe, and the residents will produce CO2 for the plants to use in photosynthesis. To ensure a healthy balance of oxygen and other gases in the breathing air for residents, sensors will monitor the concentrations of gases such as oxygen, CO2, and nitrogen. A membrane developed at MIT will separate oxygen from other gases in the agricultural ring, and this oxygen will be carried to a facility in the center ring (business/industry) of Ender (Chu, 2012). There, the oxygen will be diluted to a healthy concentration by adding nitrogen. The resulting gas will be circulated through Ender for the residents to breathe.

In each residence, there will be a ventilation system with an entrance for fresh (oxygenated) air and an air return for CO2 to leave the residence. Both the entrance and the return will be in the floor, but separated by at least a meter (to avoid having the oxygenated air go directly into the return). Because oxygen is lighter than CO2, the oxygen will rise through the residence, and the CO2 will sink towards the floor, allowing the gases to circulate. The air return will carry the CO2-rich air to the agricultural ring, where the plants will photosynthesize using the CO2 and return oxygen to the air.

To control the temperature aboard Ender, a heating and cooling system will be built into the outer wall of the spacecraft. As the spacecraft rotates to produce artificial gravity, different sections are exposed to direct sunlight, resulting in extreme temperature variations. The outer skin of Ender will be a reflective material that will reflect a majority (but not all) of the light from the sun. Some light will be purposely transferred into heat energy to avoid temperatures that are too low for the residents. Cooling tubes with circulating cold water will line the outer walls of Ender, and these will serve as the cooling system for Ender. Tubes with circulating warm water will be used in a similar fashion. The network of cool and hot water tubes will be a large network that will allow different temperature settings for different parts of the colony (for example, the side of Ender facing the sun might need to use the cooling tubes, while the side in the dark might need to use the heating tubes).

5.5 Civilian Transportation

Within the Ender settlement, aside from walking through the lattice-frame structure of the rings, the primary form of ring transportation is the tram system. The tram itself is essentially a subway train but smaller. This tram system will run on tracks that run around the circumference of the rings. The wheels of the trams will be similar to roller coaster wheel structures that wrap around the rail. This will prevent the tram from separating from the track during normal operations or if artificial gravity is not being generated.

Image from: http://www.themeparkreview.com/forum/files/inta_5.jpg

The trams mostly operate in a straight path, because curves could not fit into the lattice work. Thus, there are multiple trams constructed into the lattice-work across the width of the rings. These trams strictly run on electricity and provide the most efficient and quick means of transportation for the population to travel around the ring.

Within the center section, where there is no artificial gravity, smaller and shorter enclosed trams can take personnel throughout the center structures. The tracks for these trams run the length of the center structures, from the hangar to the evacuation center on the opposite side. These trams will be attached to the rails via wheels that wrap around the rails because if this was not done, the trams would float away.


Tram system is within these frame structures