Honeycomb Space Settlement NASA Design Competition

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Table of Contents

Preface ……………………………………………………………………….. 6 Introduction ………………………………………………………………… 8 Geometry of the settlement …………………………………........... 10 Minimum Viable Population …………………………………………. 12 Bee philosophy ………………………………………………………….... 15 Basic Module design ……………………………………………………. 16 Anatomy of a cell ………………………………………………………... 17 Technology summary............................................................. 18 Generating electricity …………………………………………… 18 Temperature control. Thermal comfort ……………….….. 20 Liquid/solid waste management ………………………….…. 22 Atmospheric composition ……………………………………… 23 Reboost technology ……………………………………………… 24 Eliminating radiation protection ……………………………. 26 Construction materials …………………………………………. 27 Safety and emergency measures …………………………….. 27 Generating gravity ………………………………………………. 28 Choosing the location ……….......................................... 30

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Table of Contents

Module lineup ……………………………………………………………. 31 The Command Center …………………………………………. 31 The Accommodation Module ………………………………... 34 The Medical Module ………………………………………….... 34 The Engineering Center ………………………………….……. 39 The Life-Support Module ……………………………………... 39 The Science/Research Lab ……………………………...……. 44 s

Building the settlement …………………………………………….… 47 Project timeline ……………………………………………………..….. 49 Health concerns ……………………………………………….………… 55 Life on board ………………………………………………………..…… 55 The future of the settlement ……………………………………….. 56 Closing remarks …………………………………………………….…… 57

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Abstract The human species is constantly evolving, taking up more and more of our planet’s resources. If the population keeps growing at the same rate it has been for the last century, a point will come when the Earth will no longer be able to support us. Studies have shown that large scale space colonies can be a viable alternative to our home planet. Our technology, however, is not advanced enough to build city-sized space settlements yet. Recent research has shown, however, that building settlements smaller than the previously accepted lower limit may be possible. In this paper, we try to find out just how small a space settlement can be, by applying recent discoveries to an older project of ours, the Honeycomb Space Settlement. The colony follows a simple, almost minimalistic modular design and is located in the Equatorial Lower Earth Orbit.

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Preface Sometimes, the best ideas come in the most unexpected ways.

Three years ago, we were both beating our brains out in an attempt to design a space settlement like no one had ever seen before. Many concepts came to us. Some were good, few were great and none stood out as truly unique. Christmas came by and we were still struggling, trying to get out of the temporary stalemate.

Then, one day, it happened. All that was necessary to kick-start our project was a sudden flash of inspiration. The answer? H oney bees. Time after time, nature has proved itself to be the greatest architect. Mankind has often borrowed elements of design from animals and plants, using them to improve existing machinery (ranging from plane wings to algorithms [5]).

During the process of creating our settlement, our first and foremost goal had always been clear: keeping the design between the bounds imposed by current, real-life technological advances. Although settlements comparable in size to the Moon are definitely interesting from a researcher’s point of view, they become mere fiction when you realize that the ISS is about the size of a football field. Our mission was that of creating a self-sustainable, highly upgradeable space station that could be in production by the end of 2025; for the most part, we have done just that. Our idea, however, was far from perfect. Space colonization is still at the earliest of stages.

Rotating a spacecraft the size of a skyscraper to simulate gravity is nigh impossible, just like properly protecting it against radiation is. This begs the question: H ow sm all can a space settlem ent be?

Fortunately, recent scientific research has shown that our design may not be that farfetched at all. In the following pages, we will try to prove that Honeycomb is closer to reality than it ever was, while also trying to find the minimum size of a potential space colony.

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Introduction

Man must rise above the Earth - to the top of the atmosphere and beyond for only thus will he fully understand the world in which he lives.

Socrates

Let us begin with a simple question which has probably crossed our minds at some point in time. Why should mankind spend time and money – both immensely valuable resources – sending people in space? Why shouldn't the government be building schools and hospitals instead of making a new telescope? Although Socrates is probably right, how can we expect to understand the world surrounding us if we do not fix what is wrong on Earth first?

Some argue that space exploration is part of our duty to our innate curiosity. Others correctly point out that space research has made our everyday life easier through inventions such as solar panels and ribbed swimsuits. However, in our humble opinion, the most compelling answer is the fact that Earth, as we know it, is not built to accommodate the human race forever. Sea levels are rising [3], climate change is wreaking havoc in areas all around the globe [4], water pollution may be at an all-time high and the population is slowly – but steadily – rising. As far as we know, our race is unique in the Universe. Therefore, we owe it to ourselves to survive and see where this journey takes us. Space colonization is one way of doing just that. At this point in time, space exploration stops being a choice and, in the words of astronaut Michael Collins, becomes an imperative.

Building a settlement capable of providing home for tens of thousands of people is definitely not an easy task. To accomplish this, we have decided on building a m inim alistic, sustainable, highly upgradeable, m odular spacecraft inspired by nature, while keeping both the cost of production and the waiting time as low as possible. Moreover, the settlement should act as an out-of-Earth observatory, providing all the necessary means for studying the world and furthering mankind’s knowledge of space.

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The Honeycomb Space Settlement is only the first step towards an extended colony, spread all across the solar system. Although this idea is beyond the scope of this project, it will be discussed briefly towards the end of the document, in an attempt to find out what the future holds for us in terms of space exploration.

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Geometry of the Settlement The Honeycomb Conjecture.

During a presentation at the 2014 ISDC, when he was asked how important the shape of a spacecraft is, Aldo Spadoni jokingly answered that, given enough rockets, anything can fly.

The shape and geometry are, without a doubt, the two most defining features of the settlement. Every other aspect, such as life on board, engine power and even the prospect of artificial gravity are strongly influenced by the outline of the spacecraft.

Therefore, choosing the shape is terms of design and functionality.

The Honeycomb Space Settlement follows in the steps of nature and takes after the honeycombs built by bees. In geometry, a two-dimensional honeycomb is a hexagonal tiling (tessellation) of the Euclidian plane, in which three hexagons meet at each vertex (also called a hextille). The internal angle of the hexagon is 120 degrees so that any three hexagons at a point make a full 360 degrees.

The two properties of a honeycomb which make it suitable for this application are as follows: 1. The hexagonal tiling is the densest way of arranging two-dimensional circles.

2. Dividing a surface into regions of equal area using hexagonal tessellation yieldsthe least total perimeter per region. [1] Out of the two theorems, the most relevant one is the latter. Known as the Honeycomb Conjecture, it was first recorded in 36BC and was proven in 1999 by mathematician Thomas C. Hales. What the conjecture tells us is that for any given settlement area, hexagons are the most efficient shape in terms of material consumption. This is highly important, seeing that the current price of taking one kilogram into space is several thousand dollars. In order to keep the settlement relatively affordable for world governments and/or private space agencies, all unnecessary costs must be brought to a minimum.

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Fig. 1.1 hexagonal lattice

Fig. 1.2 densest circle packing

Even without taking engineering and geometry into account, one can still argue that the hexagon is the most appropriate shape for our settlement, for it suits the minimalistic philosophy behind our project perfectly. Drawing inspiration from the honeycomb let us create a simple yet highly upgradeable modular design, making the colony entirely plausible with today’s technology. In our quest for finding exactly how small such a spacecraft can get, the hexagon shines through as the best candidate.

Structuring the settlement as a lattice made out of individual modules brings along several advantages over other designs. The lattice allows engineers to build new hexagonal cells both on Earth, as well as in situ, facilitating the construction process and making sure that all deadlines are met. Furthermore, advanced safety measures can be easily implemented and each cell can work autonomously, acting as a hybrid between a miniature settlement and a traditional spaceship. However, the biggest advantage will always be the reduced size resulting in the most efficient use of resources. This brings us to our next stop, which is the economic and social aspect of building our spacecraft.

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Minimum Viable Population Group Dynamics

When creating an artificial home away from Earth, one of the main concerns is making sure that the colony is sustainable in terms of population. For the Honeycomb Space Settlement, what we are most interested in is how many people are needed to keep the population on the rise, ensuring the survival of the human species.

The two most important aspects of a viable population are maintaining genetic diversity and making sure that most of the inhabitants can survive potential disasters (earthquakes, volcano eruptions etc. on Earth, explosions, system malfunctions, and collisions with asteroids in space).

When it comes to genetic diversity, estimates of the minimum viable population vary between 150 (John Moore, 2002) and 40,000 (Gardner-O'Kearnym, 2014). Although social engineering can probably bring these numbers, 40,000 is still too much for our small colony. Therefore, simply relying on the colonists to perpetuate the species is not enough. One solution is using in vitro fertilization using frozen genetic material acquired from people on Earth before launch. This would accelerate the population growth, effectively solving any issues related to gene diversity and is easily achieved with today’s technology. As soon as the population reaches the correct number, in vitro fertilization can be abandoned and reproduction can carry on naturally.

The use of genetic engineering means that the settlement can start with as few as 80100 people on board and still survive for many generations. Assuming a rate of growth of 0.012 (1.2%, slightly larger than the one on Earth)[5], the population will be reaching the required 40,000 in a little over 500 years. By the 1545th year, the population will have reached 10 billion people (assuming constant growth which should never happen in real life – the growth is most likely to slow down with time, as seen on Earth).

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Year 0 50 100 500 1000 1250 1545

Population 100 181 329 38,927 15,153,484 298,978,961 10,090,015,150 Fig 2.1 Population growth assuming r=1.2% and initial population of 100 𝑝 = 𝑝0 𝑒 𝑟𝑡

Fig 2.2 Variation in a Gene Gardner-O'Kearnym, 2014

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The second issue at hand is protecting the general population from accidents and catastrophes. In case of fire, explosions, meteor showers, system malfunction or any other issue, the number one priority is making sure the settlement survives with as few casualties as possible. Fortunately, the design of the Honeycomb Space Settlement is characteristically safe. When disaster strikes, having 10.000 people all packed together in a small place can be devastating. However, our colony’s modular design lets us split people into groups of no m ore than 100 inhabitants, creating neighborhood-like communities all across the settlement. This means that, in case of an emergency, the number of injured people will be kept down to a minimum, preventing the population from suffering too much of an impact as a whole.

One other factor which might influence the minimum population aboard the settlement is how people are going to interact with each other once in space. Living with the same twenty other individuals for eighty years can certainly change many aspects of a modern citizen’s life. To better understand this issue, we can take a look and analyze modern real-life villages from all around the globe. India, for example, has 236,004 villages with a population few er than 500, while many east-European countries have villages with fewer than 100 people living in them

[2]

. Therefore, one can assume

that 80-100 is the lower bound of a human settlement.

In a settlement where everybody knows everybody, however, life can prove difficult at times. The lack of privacy and secrecy can be frustrating, while fights over unimportant matters can often ruin the mood across the entire spacecraft. We believe that as the colony grows, the entire dynamic of the groups aboard will follow the change, slowly evolving towards what we see on Earth. People will be able to choose their friends instead of being forced to live with someone they do not like and relationships will start playing a more important role in everyday life. As studies have shown, individuals tend to change their behavior in order to fit into a group. Moreover, research done on American and Russian astronauts aboard the ISS shows that life in space can have severe psychological and behavioral effects, such as depression, suicidal thoughts, psychotic thinking caused by stress, communication misunderstandings, changes in attitude and negative emotions towards other people. One way of reducing such problems is keeping everyone on board involved in teambuilding exercises, joint celebrations and cooperative activities.

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As a conclusion, evidence seems to indicate that 80-100 people led by a capable leader is the lower limit for a permanent space settlement, allowing for Earth-like population growth and allowing the human species to thrive.

Bee Philosophy While working on the original Honeycomb Space Settlement, our main focus was creating a simple yet highly efficient home for hundreds, even thousands of people.

With this version of the settlement, we have decided to keep true to our minimalistic philosophy, making the colony as affordable and easy to build as possible.

In one of Plato’s famous dialogues - The Republic -, we find Socrates explaining how the best state is the one in which each part of the whole performs only its work, without meddling in the performance of work belonging to other parts. Following his reasoning, we have decided that a modular design in which each cell acts as an individual, specialized spacecraft is best suited for our idea.

The four keywords we are going to look upon in the subsequent chapters are as follows: 

sim ple



in the process of designing the modules, keeping the complexity of our settlement to a minimum is crucial sustainable



although shipping supplies from our home planet is a temporary option, our goal is that of creating a colony which will allow the human species to thrive without any external help upgradeable science has been constantly evolving for as long as we can remember; today’s technology could become obsolete by the 50 years mark, which means that our



spacecraft should be easily upgradeable affordable we believe that once the price of building the settlement exceeds mankind’s current possibilities, that design becomes useless; therefore, the Honeycomb Space Settlement should be as inexpensive as possible, without sacrificing any aspect of its performance

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Following these four concepts, we have divided our settlement into six different modules, each with its own precise role. The Accommodation Module, the Science and Research Laboratory, the Life-Support Module, the Engineering Center, the Medical Module and the Command Center are, therefore, the building blocks of our future colony.

Basic module design Although our settlement comprises six different types of cells, each and every one of them has several key features in common. The basic module design is the foundation for every other component of the settlement, providing a flexible framework for scientists and engineers to improve upon. The hextille can be easily upgraded by removing or adding new modules as necessary.

Our attempts to create the perfect environment for the inhabitants of the settlement have led us to the current cell design. The basic module is made out of six walls surrounding three floors in a hexagonal fashion. Every module is equipped with its own life support system, engines and solar panels, meaning that the cell is, by all means, a fully functioning, self-sustainable spacecraft.

Module Specifications Height (m) Edge length (m) Diagonal length (m) Floor surface (m2) Volume (m3) Area covered by photovoltaic cells (m2) Starting population Maximum population

12-16 40 80 4157 ~58200 3000 60 100

(Numbers displayed in the table above are only approximations computed using the formulas for a hexagon’s area and volume) The module’s engines are used both for relocating the settlement in case of an emergency, as well as for correcting the spacecraft’s trajectory along the orbit. The photovoltaic panels occupy three quarters of the floor’s outer surface area, providing energy to the entire cell.

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Technology Summary Among the common features which all modules share, there are several technological components which are worth mentioning. These elements of our settlement often have crucial roles in making life in space possible and are, therefore, some of the most important aspects of our design.

Generating Electricity One can say for certain that the functionality of any settlement is heavily influenced (to the point of being constrained) by the amount of available power. The main source of electricity aboard our modules is the use of photovoltaic solar panels to obtain electricity from sunlight. After analyzing all possibilities, we have decided to use multijunction solar cells which have lab-tested efficiencies of over 40% (with a maximum limiting efficiency of 86.8% under highly concentrated sunlight) and are identical to the ones utilized in the Mars rover missions. [7]

Categories Crystalline silicon cells Thin film solar cells Multi-junction cells

Technology Monocrystalline Polysilicon Amorphous silicon CdTe CIGS MJ

η (%) 24.7 20.3 11.1 16.5 19.5 40.7

W/m2 63 211 33 126 n/a 476

Using the above table, we can compute the power output of the MJ cells on the H oneycom b Space Settlem ent to be 3000 x 476 or 1.42800 megawatts.

Although solar energy is a great short-term solution, we believe that our long term goal should be a switch towards nuclear fusion as a source of energy. Considering the recent breakthrough discoveries of the scientists working at the Wendelstein 7-X (W7X) nuclear reactor (generating hydrogen plasma) we believe that fusion based nuclear power will be available in the next 10 years. As a consequence of our settlement’s modular, upgradeable design, the idea of creating a reactor cell should be taken into consideration.

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Fig 5.1 Picture showcasing the solar panels located on the bottom of every module.

Fig 5.2 The structure of a multi-junction solar cell. .V.Yastrebova (2007). High-efficiency multi-junction solar cells: current status and future potential

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Temperature Control and Thermal Comfort One essential factor which allowed life to survive and evolve on Earth is the air temperature (a direct implication of our location relative to the Sun). An individual’s satisfaction with the thermal environment is called thermal comfort and maintaining this standard across our entire settlement has been one of the important goals when coming up with the design.

Controlling the rate of heat gain and loss is the first step in assuring thermal comforts for the inhabitants of the spacecraft. There are six factors that directly affect the comfort levels and they can be grouped in two categories: personal factors and environm ental factors.

Personal factors: 



metabolic rate – the level of transformation of chemical energy into heat and mechanical work by metabolic activities within an organism (ASHRAE 55-2010) 1 met = 58.2 W/m² common values are 0.7 met for sleeping, 1.0 met for a seated position, 1.2-1.4 met for light activities standing, 2.0 met or more for activities that involve movement clothing insulation – thermal insulation provided by clothing 1 cl = 0.155 m²·K/W (trousers, a long sleeved shirt, and a jacket)

Environmental factors  

air temperature mean radiant temperature (radiant heat transferred from a surface)

 air speed (just as important in space as it is on Earth, preventing regions of 

toxic gas from forming in the absence of air currents relative humidity

The four environmental factors are controlled by the spacecraft’s life-support system, which draws inspiration from the International Space Station’s own ECLSS.

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Module pressure range Partial pressure of O2 (inhaled) Partial pressure of CO2 Partial pressure of H2O Air temperature Air circulation rate Relative humidity

14.2 to 14.9 psi 150-200 mmHg 6 mmHg, max 10 ± 5 mmHg 18 to 26 ˚C 0.1-0.4 m/sec 50-60%

Almost all of the spacecraft’s systems generate heat, which needs to be removed from board in order to maintain appropriate living conditions. This is achieved using two heat-control systems: a passive one, consisting of special materials, coatings, insulation and heat pipes, and an active system comprising thermal radiators situated in proximity of the solar panels.

The thermal radiators keep all the spacecraft parts within acceptable temperature ranges during all mission phases by radiating heat energy away as light in the absence of a conduction/convection friendly medium.

Doing the opposite job – which is keeping the crew and temperature above their lower temperature limit during cold phases – are the thermostatically controlled resistive electric heaters and the fluid loops composed of heat pipes. All systems have the job of making sure that the cabin temperature never drops below the 18˚ C lim it. The delicate balance between too hot and too cold is carefully maintained by the on-board computers, which can also connect to the Command Center for additional processing power.

thermal radiators operating in the infrared spectrum

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The radiators reject between 100 and 350 W of internally generated heat per square meter, which means that the entire array can radiate up to 84000 W or 0.084 m egaw atts.

Liquid and Solid Waste Management Everyone knows how important water is. Human beings require constant hydration during for every day of their life. Recycling water on board of the settlement is, therefore, a key aspect of life in space.

The walls of the water collection modules are covered in a special material discovered by mechanical engineer Kyoo-Chul Park and his team of researchers. The results of his research, published in the February edition of the Nature journal [8], describe a beetle-inspired material which condenses airborne water vapor into liquid 10 tim es faster than any other known material. After collection, the water is purified and sent back to the spacecraft’s crew systems.

Fig 5.5 Time-lapsed images of droplets condensed on slippery surfaces (Kyoo-Chul Park and Joanna Aizenberg)

When it comes to fully recycling solid waste, no current technology can be considered economical enough to be put into practice. However, after the extraction of water, remaining waste can be partially transformed into fertilizer or fuel.

In spite of the high performance of the water purification system, the settlement may require additional refills from Earth or from comets.

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Atmospheric Composition The atmosphere aboard the Honeycomb Space Settlement is a standard, Earth-like mixture of nitrogen (79% ) and oxygen (21% ) [9]. The main advantage that the mix has over a pure oxygen atmosphere is the increased safety (especially against fire, which can be incredibly problematic, as shown by the Apollo 1 mission). However, the spacecraft’s life support systems can always reduce the nitrogen levels while increasing oxygen, in order to make the settlement lighter (by removing the need for a large number of nitrogen tanks) and to minimize the effects of decompression sickness.

Fig 5.4 Diagram of the life support system aboard the Honeycomb Space Settlement[10][11]

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Reboost Technology One can find advantages to every possible location, but the general consensus is that placing your settlement closer to the Earth will result in significant atmospheric drag.

Although research indicates that micro-particles in the Low Earth Orbit are quickly absorbed by the Earth’s atmosphere [12], frequent collisions of gas molecules with the settlement can result in orbital decay [13]. Furthermore, the more the orbit decays, the lower the altitude of the settlement drops, speeding up the decay process. This positive feedback effect can be countered by periodically adjusting the colony’s orbit. Two ways of achieving the desired result are pushing the settlement back on its path using a second spacecraft’s engines or using the settlement’s own to correct any deviation.

Every module in the Honeycomb Space Settlement has three large engines available for any task which might require propulsion, including reboosting. Additionally, there are five other hidden engines on every side of the cell, used for steering and fine-tuning any location related aspects.

The engines have a radius of 6 m eters (20ft) and can provide up to 35 m illion horsepower or 26099495 kilowatts. When not in use, the power is redirected from the engines to the rest of the settlement.

In case of an emergency, the engines are immediately enabled and assigned the task of removing the module from the lattice and transporting it towards safety. In the unfortunate event of system malfunction, the engines are powerful enough to push a disabled module which has been connected to the main cell.

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Eliminating Radiation Protection Up to 90% of a spacecraft’s weight is in radiation shielding. In our quest to create the lightest, smallest, simplest space settlement, we have searched for ways of reducing this unneeded weight by as much as possible, to the point of completely eliminating it.

The unit used for measuring small ionizing radiation doses and their impact in the International System of Units is the Sievert. It has been shown that 1 Sievert is enough to raise the probability of eventually developing cancer by 5.5% . [14][15] Dose examples in Sieverts[16][17]: 0.098 μSv 0.2 μSv 5 to 10 μSv 10 to 30 mSv 80 mSv 250 mSv 1 Sv:

radiation from a typical banana a single airport screening in the U.S. one set of dental radiographs full-body CT scan 6 months stay on the International Space Station 6 months trip to Mars maximum allowed exposure for NASA astronauts over their career

Even more important in the context of space travel are the radiation dose rates. Below are several examples[18]:

2.4 mSv/a 24 mSv/a 9Sv/a

human exposure to natural background radiation, global average natural background radiation at airline cruise altitude NRC definition of a high radiation area in a nuclear power plant

In his 2015 paper – Orbital Space Settlement Radiation Shielding [19] – Al Globus has shown that human adults can withstand radiation levels of up to 20 m Sv/year, while pregnant women have a threshold of 5m G y/pregnancy.

According to the same research paper, placing a settlement in the equatorial Lower Earth Orbit (ELEO) where the radiation levels are at their lowest point, one can virtually eliminate the need for any radiation protection. This is hugely important for the Honeycomb Space Settlement, as it fits the minimalistic philosophy of our entire project. Removing radiation shielding will lower both weight and costs, as well as the construction time.

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Construction Materials By removing radiation protection from the equation, the job of choosing the materials for the settlement has become a lot easier. The list of construction materials for the Honeycomb Space Settlement is taken from an MIT paper detailing the Space Station Requirements for Materials and Processes.

Material used in the fabrication of the hardware on the settlement is selected by considering the operational requirements for the particular application. This includes operational temperature range, life expectancy, resistance to impact and aesthetic qualities. The materials employed in the construction of the settlement should overcome issues such as outgassing and mechanical fatigue.

Based on the MIT paper, we can say that Aluminum alloys 2024-T6, 7079-T6, and 7178-T6 shall not be used in structural applications, while alloys 5083-H32, 5083-H38, 5086-H34, 5086-H38, 5456-H32, and 5456-H38 should not be used in applications where temperature exceeds 150 degrees Celsius. Furthermore, steel should be carefully treated and any drilling should be avoided. Magnesium, Beryllium, Cadmium and Mercury should also be used only in non-primary structural applications. Other materials used include plastics, carbon nanofiber and lead lined glass.

Safety and Emergency Measures History has shown that accidents can have tragic consequences in space. It is, therefore, our moral duty to prevent such events from ever happening again. The modular design of the settlement is its strongest safety measure: if anything happens in one module, the cell can be safely evacuated and removed from the grid by detaching the connecting bridges. This way, any sort of catastrophe can be contained, limiting causalities and bringing structural damage to a minimum. The colony’s proximity to Earth is also an advantage, allowing for easy emergency trips between the spacecraft and our home planet.

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Generating Gravity

It has long been known that prolonged exposure to micro-G environments can affect the human body in a multitude of ways. Medical conditions often associated with weightlessness include (but are not limited to) m uscle atrophy, loss of bone tissue, disorientation and nausea (including already infam ous space adaptation syndrom e), fluid redistribution inside the hum an body, cardiovascular problem s, w eight loss and changes in stature . Furthermore, studies have shown that reproduction might be problematic, with embryos failing to properly develop in micro-G environments.

Many of the negative side-effects of life in space can be completely mitigated by implementing artificial gravity on the settlement. Traditionally, other designs have achieved this by rotating the spacecraft, creating a pseudo-gravitational force perpendicular to the axis of rotation (courtesy of Newton’s laws). This force required for maintaining steady, 1 G acceleration is greatly influenced by the distance from the center of rotation and by the number of rotations per m inute . The two variables are inversely correlated, meaning that as the size of the spacecraft increases, the RPM required for artificial gravity decreases. This puts us in a bit of a difficulty; one hand, designing a large settlement is completely contradictory to our minimalistic philosophy. Furthermore, construction and maintenance costs may render this idea economically infeasible. On the other hand, a small settlement will require a large number of rotations per minute, which can raise additional health issues and will require more complex technology.

where: g = fraction of Earth’s gravity R = radius from rotational center

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A second research paper published this year by Al Globus [20] - Space Settlement Population Rotation Tolerance – has dived straight into this issue, trying to find the perfect equilibrium between settlement size and RPM. As the paper clearly explains, although the number of rotations is constant across a settlement, the rotation radius of people moving through the spacecraft is not. This means that the inhabitants will need to adapt to changing levels of rotation. Gravity will most likely not be constant across the spacecraft, with higher centripetal force values. Studies have shown that adaption to RPMs of up to 5.4 can be achieved in a matter of days [Graybiel 1977].

Coincidentally, the 40m radius of our settlement corresponds to approximately 5 rotations per m inute , well within the 6rpm comfort boundary [Gilruth 1969].

Artificial gravity distribution on a module; the centripetal force is generated by spinning the circular interior of the module around the central axis.

Our initial Honeycomb design implemented no artificial form of gravity because of the economic implications and health concerns associated with high RPM. H ow ever, the findings presented in the above paper have allow ed us to create a functional space settlem ent m odule that can successfully sim ulate gravity and has a m axim um diam eter of 80 m , only 8 m eters longer than the International Space Station.

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Choosing the Location

One other factor that can strongly influence the size and the costs of the project is the location of the settlement. Although both the Lagrangian points and the geosynchronous equatorial orbit are stable enough to allow the building of settlements, the distance factor alone is enough to make the Low Earth Orbit (LEO) a better candidate.

Placing the settlement in the LEO has several advantages, as well as quite a few disadvantages. The good news is that, as we have already discussed, the Equatorial Low Earth Orbit virtually eliminates the need for radiation protection, reducing weight by 90%, cutting production costs by a large margin and making the settlement overall easier to build. Furthermore, the short transit time between the colony and Earth means that materials and even people can be quickly delivered, making the space settlement safer in case of emergency. On the opposite side, placing the settlement too low in orbit can result in severe orbital decay which might pose serious dangers to the population on board. Additionally, being so close to Earth can diminish the spaceoutpost role of the colony by being too far away from any other astronomical objects.

𝐹𝑛𝑒𝑡

𝑀𝑠 ∙ 𝑣 2 = 𝑅

𝐹𝑔𝑟𝑎𝑣 =

𝐺 ∙ 𝑀𝑠 ∙ 𝑀𝐸 𝑅2

By setting the two forces above equal, we get 𝑣 = √𝐺 ∙

𝑀𝐸 𝑅

Which is approximately equal to 7.8 km /s for a circular orbit of 400 km above Earth.

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Module Lineup We are now going to take a look at the individual cells of our honeycomb. In our attempt to create the smallest functional settlement, we have chosen a minimalistic approach which will allow us to reduce production costs to a minimum while keeping the performance of our spacecraft at the highest possible level.

Each module employs state of the art technology to complete its tasks and provide shelter for its inhabitants. Although every cell is virtually a fully independent station, all six cells start working together and exchanging functionality once connected to the lattice. The module responsible for mediating these interactions is the Command Center, which we are going to talk about now.

The Command Center If our settlement was a human body, the Command Center would be the brain. Even better, if our settlement was a real honeycomb, the Command Center would be the Queen, making sure that everything works as intended.

The Command Center is crucial to the well-being of the entire settlement. One individual module would have no problem functioning by itself – the life support technology can maintain the population alive and the only task the system has to keep in mind is fulfilling its own needs. Once you start adding other cells (which is sooner rather than later, if we want our colony to expand), things change. Just as in any other real-life scenario where a number of similar entities are brought together, there needs to be a leader.

The Command Center is the central processing unit of the entire colony. Although it may look like any other module, it serves the crucial purpose of mediating the interaction between any other cells. This includes maintaining constant air pressure and oxygen levels across the lattice, acting as a reference point for every other system on board.

Because the task of coordinating individual elements of the hextille becomes a real issue only after the first two or three modules are already in space, the Command Center will be sent away from Earth later than other cells.

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The Accommodation Module The Accommodation Module is where every person aboard the Honeycomb Space Settlement lives, sleeps, eats and spends their free time. Complete with bedroom s, m edia room s, conference halls, dining room s and even coffee shops, the Accommodation module is designed to offer the complete space experience to every citizen of the colony and is the first cell to be sent into space.

The module is designed to provide accommodation in the form of 20 double room s and 40 single (one bed) room s. Each corner of the cell will be accessible via corridors, allowing easy interaction between the inhabitants.

Our main goal when designing the Honeycomb Space Settlement was keeping it as sim ple and easy to understand – and build – as possible. However, we do realize that long term space colonization means that the population on board will be constantly growing. This brings us to another advantage of the hexagonal lattice design – more accommodation modules can always be added, meaning that there is virtually no population limit.

The Medical Module With life in space comes a plethora of medical issues, ranging from the not so impressive decompression sickness to the weird behavior of bacteria in low-G environments. Keeping the population healthy is, therefore, absolutely crucial to the success of our mission.

The Medical Module is equipped with cutting edge medical technology, operated by a team made out of the best doctors from Earth. Furthermore, the module will help in maintaining muscular atrophy at bay by offering gym equipment to crew members and civilians living aboard the spacecraft. Although this cell is not a top priority, we believe that once two or three Accommodation modules are already in place, sending a Medical Module can greatly help in reducing the risks associated to life in space. If any sort of emergency requires medical attention greater than what is available in space, the cell is equipped with escape pods which can return humans back on Earth in less than twelve hours.

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The Engineering Center When planning for life in space, it is best to assume that as long as something can go wrong, it most certainly will. Things break all the tim e on Earth. Why would it be any different in outer space?

Unfortunately, system failures can be much more dangerous when you are 1000 kilometers above the highest point on Earth. For such extreme situations, we have designed the Engineering Center – a repair shop for the entire settlement.

The Engineering Center is equipped with hundreds of miniature robots created to detect and fix any issue within the colony. Even more, this is where well trained engineers spend all their time and effort trying to find ways of structurally improving the existing modules. The Engineering Center serves a crucial role in the weekly maintenance, providing all the necessary means for properly inspecting and analyzing the rest of the settlement.

The Life-Support Module The Life-Support Module serves a similar task to the Command Center. If more than two Accommodation modules are present in the lattice, managing water, air and any sort of waste becomes easier by employing a specialized module. The cell is equipped with high performance purification systems, doing the job of the basic life-support system present in every cell by up to 1000% better.

The Life-Support Module is permanently connected to the Command Center, monitoring Oxygen and Nitrogen concentrations all across the settlement, as well as other factors such as pressure and partial humidity. The fluids collected from other modules are redirected to the cell by several hidden ducts, processed and then sent back ready for use.

Once there are enough people on the settlement, the Life-Support Module can also be used as a dedicated platform for agriculture and even livestock.

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The Science and Research Laboratory As previously stated, we believe that rigorous scientific research is mandatory for the proper evolution of the human race. Therefore, although primarily a home for thousands of people, the Honeycomb Space Settlement will also serve the noble role of acting as an out-of-Earth laboratory for scientists living on the colony.

It is our opinion that nothing is more satisfying than studying the Universe right from the depths of space and we truly hope that the technology on the settlement will allow researchers to uncover more of life’s mysterious background.

The domain we are most enthusiastic about is the recent observation of gravitational w aves by Caltech scientists at LIGO

[21]

,as predicted in 1916 by Albert Einstein’s

theorem of general relativity. We hope that scientific advance will allow us to shrink the sensors needed for direct observation of gravitational waves to the point where the phenomenon can be clearly seen and studied from aboard the settlement. By analyzing the effects of gravity over such long distances, we can find out more about stars, planets and black holes far away from Earth. Over time, this might help us understand the origin of our planet, the Sun and life itself.

Other research topics include – but are not limited to – the study of solar w ind and solar sails, the C osm ic B ackground R adiation , quantum m echanics, biological and psychological effects of life in space over the hum an body, the im pact of raising children aw ay from Earth, asteroid m ining, space cleaning, nuclear energy and the possibility of launching m anned m issions from our settlement towards the Moon, asteroids and even remote planets, such as Mars.

Furthermore, the settlement’s observatory could focus on interstellar magnetic fields similar to the ones discovered by NASA’s IB EX mission and published in the Astrophysical Journal Letters in February 2016. The research done inside the colony may actually prove helpful in improving the existing modules. Alternatively, new technology could be used in newer cells, which will be built right inside the lattice.

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Building the Settlement

The process of building the modules can start as soon as the final design is ready and funding for the project is approved. In order to maximize the use of time and other resources, we believe that the Honeycomb should be built as a joint project between government forces and private space agencies.

The first few modules will be made out of parts created on Earth and assembled in space.

This way, components can be shipped from Earth as soon as production ends, reducing associated deadlines by more than half. The delivery will be done by Space X Falcon 9 or a newer generation of reusable rockets.

The actual building process will be supervised by engineers living in temporary space camps for up to six months. Once the first Accommodation module is ready, the first group of people can start living on the settlement. As the number of cells in the lattice grows, so will the settlement’s autonomy and independence from Earth.

Unfinished honeycomb cell.

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Stage 2 of the construction process: two Accommodation modules and the Command Center

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Project Timeline

0

Funding is approved – production of the first components begins

1

Rocket and delivery systems testing is started

3

The first components are sent into space

5

Assembly begins in the Lower Earth Orbit

8

Parallel work on the second module begins

10

The first Accommodation Module is completed; population - 40

15

Work on the Command Center begins; population - 80

20

The Command Center, second Accommodation Module are launched

25

Work on 2-4 other modules is completed, including utility cells

50

All six types of modules are now in orbit

75

6 accommodation cells in space

100

Population has grown to 330

150

Researchers start upgrading the Honeycomb; new cells added

200

Plans for a second colony near Mars

250

Mars colony operational

500

Population reaches 40,000

750

Two more colonies are added in our Solar System

1000

Population reaches 15,000,000

1500

Population exceeds 10 billion. Majority of human species is now living in space

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Stages 3 and 4

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Possible layout for a completed settlement

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Health Concerns Most of the typical health issues correlated to life in space have been solved by implementing artificial gravity aboard the Honeycomb Space Settlement. Most problems that remain are either related to the effects of rotational environments on the human body or to the psychological aspects of life in space.

Nausea and dizziness can be easily repressed through training and adaptation to space.

However, even something as benign as the common flu can wreak havoc in a small, closed environment. Therefore, all people must be treated and tested for any contagious disease before being allowed to live in space.

When it comes to treating psychological aspects, such as depression, mood swings or unusual behavior, maintaining proper communication between inhabitants and identifying issues before they become a problem is crucial. Although not many studies have been done on the subject, we can analyze other contexts, such as the Nordic countries where low levels of sunlight have been known to cause depression

Life on Board Although it is our firm belief that functionality should come before comfort when pioneering space settlement technology, we do realize that any evolving human community needs some form of entertainment to stay healthy. Therefore, we have tried to make life on the settlement as similar as possible to the one on Earth. This means celebrating holidays like Christmas and the New Year, as well as introducing new ones like the Honeycomb Day. In order to keep everyone active, each citizen of the settlement will have certain tasks, inspired by the jobs people take on Earth. Moreover, the colony will require some sort of government. For this project, we have decided not to go any deeper into this issue which we have addressed on numerous occasions in the past years.

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The Future of the Settlement Designing one settlement is only the first step in the difficult, highly ambitious yet beautiful journey of space exploration and colonization. Just like Neil Armstrong and Buzz Aldrin were the first of a long series of people on the moon, the settlement described in this project is merely one component of a larger colony of settlements spread across the entire Solar System.

Our long term plan is creating a web of autonomous space stations, just like the ones often depicted in science fiction works. We believe that our minimalistic approach is perfect for creating a real network of space cities. This implies that – as soon as the economic and technological means are available – we should start building additional settlements in the vicinity of Mars, Venus, even the asteroid belt or the gas giants.

Our hexagonal lattice design has a virtually unlimited number of slots available for new Accommodation modules to be built. However, creating other groups of cells in different corners of space can prove advantageous, providing valuable insight into the deepest mysteries of the Universe and allowing the human race to spread and evolve like never before.

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Closing Remarks For our third year in this competitions, inspired by the events at the 2015 ISDC, we have decided to revive our very first settlement idea: the Honeycomb. Not because it was easy, not because it was simple, but because we believe that recent discoveries have made our design closer to reality than ever. A simple (yet complex) modular design is the only way in which we can start sending people to live in space in a reasonable amount of time.

To us, the Honeycomb is more than a geometrical array of shapes. In it, we see the future of space exploration. By putting all the pieces together and designing the settlement, we have embarked on a great journey with an even greater reward. For now, we believe that we have achieved our goal of creating the smallest, simplest functional space colony. However, we also know that anything can be made better with enough patience and care. We promise to keep searching for ways of making our settlement cheaper, stronger and even easier to comprehend.

C ontact light.

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References D. Donovetsky, M. A. Ionescu (2014). “Honeycomb Space Settlement” NASA Space Settlement Design Contest 10th grade 1st prize D. Donovetsky, M. A. Ionescu (2015). “Dandelion Space Settlement” NASA Space Settlement Design Contest 11th grade 2nd prize “Launching genetic diversity to the stars” (2014) http://johnhawks.net/weblog/topics/space/effectivesize-starship-smith-2014.html “Safety in Numbers” (2002) http://www.economist.com/node/998489 “How

Many

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Colonize

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Star

System?”

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http://www.popularmechanics.com/space/deep-space/a10369/how-many-people-does-it-take-tocolonize-another-star-system-16654747/ [1] Hales, Thomas C. (2001). "The Honeycomb Conjecture". Discrete and Computational Geometry 25 (1): 1–22. arXiv:math/9906042. doi:10.1007/s004540010071. MR 1797293 [2] “Population Density: How Many in that Kingdom?” www222.pair.com/sjohn/blueroom/demog.htm [3] Robert E. Kopp, Andrew C. Kemp, Klaus Bittermann, Benjamin P. Horton, Jeffrey P. Donnelly, W. Roland Gehrels, Carling C. Hay, Jerry X. Mitrovica, Eric D. Morrow, and Stefan Rahmstorf Temperature-driven global sea-level variability in the Common Era PNAS 2016 ; published ahead of print February 22, 2016, doi:10.1073/pnas.1517056113 [4] "The Impacts of Increasing Drought on Forest Dynamics, Structure, and Biodiversity in the United States," James S. Clark, Louis Iverson, Christopher W. Woodall, Craig D. Allen, David M. Bell, Don C. Bragg, Anthony W. D'Amato, Frank W. Davis, Michelle H. Hersh, Ines Ibanez, Stephen T. Jackson, Stephen Matthews, Neil Pederson, Matthew Peters, Mark W. Schwartz, Kristen M. Waring, Niklaus E. Zimmerman. Global Change Biology, early online Feb. 22, 2016. DOI: 10.1111/gcb.13160 [5] Population Reference Bureau. "2013 World Population Factsheet" (PDF). www.pbr.org. Population Reference Bureau. Retrieved 5 December 2014.

[6] A Brief Review of Nature-Inspired Algorithms for Optimization Iztok Fister Jr. 1 , Xin - She Yang 2, Iztok Fister 1, Janez Brest, Dusan Fister

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[7] D. Crisp, A. Pathareb and R. C. Ewell (2004). "The performance of gallium arsenide/germanium solar cells at the Martian surface". Progress in Photovoltaics: Research and Applications 54 (2): 83– 101. Bibcode:2004AcAau..54...83C. doi:10.1016/S0094-5765(02)00287-4.t [8] Kyoo-Chul Park, Philseok Kim, Alison Grinthal, Neil He, David Fox, James C. Weaver & Joanna Aizenberg “Condensation on slippery asymmetric bumps” Nature 24 February 2016 [9] Zimmer, Carl (3 October 2013). "Earth’s Oxygen: A Mystery Easy to Take for Granted". New York Times.

[10] http://wsn.spaceflight.esa.int/docs/Factsheets/30%20ECLSS%20LR.pdf [11] http://suzymchale.com/ruspace/issrslss.html#ch4 [12] “The LEO microparticle population: Computer studies of space debris drag depletion and of interplanetary capture processes P.R. Ratcliff”, A.D. Taylor, J.A.M. McDonnell [13] Microparticle Populations at LEO Altitudes: Recent Spacecraft Measurements Icarus, Volume 127, Issue 1, Pages 55-64 J.A.M. McDonnell, P.R. Ratcliff, S.F. Green, N. McBride, I. Collier [14] Brenner, David J.; Hall, Eric J. (2007). "Computed Tomography — an Increasing Source of Radiation Exposure".

New England Journal of Medicine 357 (22): 2277–2284. doi:10.1056/NEJMra072149. PMID 18046031.

[15] Hart, D.; Wall, B. F. (2002). Radiation Exposure of the UK Population from Medical and Dental X-ray Examinations (PDF). National Radiological Protection Board. p. 9. ISBN 0 85951 468 4.

Retrieved 18 May 2012.

[16] American National Standards Institute (2009). Radiation Safety for Personnel Security Screening Systems Using X-Rays or Gamma Radiation (PDF). ANSI/HPS N43.17. Retrieved 31 May 2012.

[17] US Nuclear Regulatory Commission (2006). Regulatory Guide 8.38: Control of Access to High and Very High Radiation Areas in Nuclear Power Plants (PDF).

[18] Bailey, Susan (January 2000). "Air crew radiation exposure—An overview" (PDF). Nuclear News.

Retrieved 19 May 2012.

[19] Globus, Al (2015) “Orbital Space Settlement Radiation Shielding” [20] Globus, Al.; Hall, T. (2015) “Space Settlement Population Rotation Tolerance” [21] B. P. Abbott et al.* (2016) “ Observation of Gravitational Waves from a Binary Black Hole Merger” http://www-spof.gsfc.nasa.gov/stargaze/Slagrng2.htm http://www-spof.gsfc.nasa.gov/stargaze/Slagrng3.htm http://adsabs.harvard.edu/full/1967AJ.....72..173D http://settlement.arc.nasa.gov/designer/needs.html http://fnic.nal.usda.gov/lifecycle-nutrition/fitness-and-sports-nutrition

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Thank you very much for taking the time to read our submission.

Mihai Alexandru Ionescu, 12th grade, Bucharest, Romania Daria Suzanne Donovetsky, 12th grade, Bucharest, Romania Coordinated by Ioana Stoica Tudor Vianu National High School of Computer Science

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