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Alternative design of a for human habitability Ahmad Fariq Irfan Bin Ahmad Fakhri Universitat Politècnica de Catalunya UPC, Departament de Física, Av. Víctor Balaguer 1, Vilanova I la Geltrú-08800, SPAIN [email protected] Abstract occurred such as tsunamis, earthquakes and erupted volcanoes. Pollution such as global warming, which is mainly man-made In this project, I will be proposing my own idea of an alternative pollution due to humans using technologies and industry that design of a space station for human habitability. Throughout the emit greenhouse gasses are the common cause for the pollution; report of this project, I will mostly call it a instead making the gradually dying. of a space station for the design of this project. Before I can propose an alternate design of the space habitat, I will first be More of the reason for that, we should brainstorm and think of studying the fundamental terms and knowledge related to it so any possible solution be it short-term or long-term plan for the that I can come to a solution for the design. The challenges of perseverance of Earth and humankind. One of the solutions for living in a space environment will be studied and presented in the long-term plan is to commence a long-term plan for the this report. Two of the famous existing space stations designs survivability of humankind by building a space station for for human colonization will be studied to know the principal human habitability, or we should call it a space habitat. requirement to build a space station for human habitability and Human life can be maintained in space environments by two of the space stations from famous science-fiction movies creating a place that can replicate the earth's environment. Thus, will also be studied to gain ideas on structuring the design of that is the purpose of a space habitat. The idea of it is by creating the space habitat of this project. The design for the space habitat a space station with a capability to house up to million or if will be presented in the project that is done using Siemens possible, billions of humankinds. This solution will reduce the NX12 PLM Software. The key characteristic of the space population of humans on earth and greatly minimize pollutants. habitat will also be presented in this report such as how artificial As a result, the earth 's environment will gradually start to gravity is generated inside the space habitat, the estimation of recover and solve the lack of resources problem. This solution the population that can be accommodated inside the space clearly will benefit both humankind and the Earth. habitat, the Coriolis effect experienced inside the habitat, the power source, lighting system and the thermal control system 2- Challenges living in space of the space habitat. As a conclusion of this project, the design that has been made will be compared to the other space stations 2.1- Vacuum for human habitability that have been studied. Finally, suggestions for improvement will be given in the case of any The Earth's atmosphere serves as a barrier to keep the heat and further studies or research on this project. oxygen needed for life contained [3]. In comparison to Earth, the high vacuum in space causes the atmosphere in space to Keywords: Rotating Space Habitat; Space Station; Artificial have extremely low pressure and there will be no air. Humans Gravity; Coriolis effect; Solar panel; Angular velocity; need to be in a pressurized environment to live [3]. To make it ; ; Habitability of a space station; simple, humans need to live in an environment which the air Siemens NX12 has a good amount of breathable oxygen molecule. 1- Introduction 2.2- Debris

It is estimated that the Earth will reach its maximum human Earth's orbital is surrounded by the orbital debris which consist capacity by 2100 [1] which is not far from now. This is because of many particles [3]. The debris floating around the Earth's the human population has been increasing exponentially since orbital consists of natural debris such as meteoroids and human the early 1900s [2]. generated debris. To design the space habitat, this factor needs to be considered and a design of a layer that will act like an Apart from the problem of human population, several other outer shell of the design should be considered to protect the problems regarding lack of resources, and pollution have been space habitat from the impact of the debris. reported all over the world. Many natural disasters have

2.3- Gravity 2.5- Power source

Technically, there is no place with no gravity as gravity does Humans need electricity as the main power supply for our home exist everywhere in the universe [4]. However, compared to the or any other industrial works. The electricity we obtain is Earth gravity with the approximation of 9.81m/s2 [5], the generated from several types of natural resources such as oil, gravity in the space environment is far lesser. When the forces coal, gas, renewable energies and many more. As of the year of gravity are not felt, the feeling of weightlessness, or zero 2020, research stated that the majority of electricity comes from gravity, occurs [4]. This is what astronauts and cosmonauts felt coal and followed by gas, nuclear, hydropower, other renewable when in the space environment. energies and finally oil [8].

The difference in atmosphere compared to Earth, brings some negative effects to the human body as our body is accustomed to the Earth atmosphere. One of the common negative effects that will happen is the constant bone loss throughout the duration in the space environment. The phenomena of this bone Figure 2: Statistical review of the source of electrical energy. loss are called spaceflight osteopenia [6]. After some research Source [8] on the problem, it is deduced that the human skeleton seemed to thin due to the lack of gravity [7]. To build a space station for the space environment however, it will be a major problem as it would be very difficult with the very limited number of natural resources that we can find to produce electricity for the space station. For this project, which the space station will be in the space atmosphere and away from the Earth, most of the resources are not found here. Other renewable resources such as wind might not be possible as there Figure 1: Example of spaceflight osteopenia. Source [5] is no air in the space atmosphere, hence wind as a source to Other than the effect of bone loss, the people who live in the produce electricity might not be practicable. So, in this project, space atmosphere will experience the loss of the sense of these problems of lacking resources to generate electricity will direction, perceptiveness and orientation. This is due to be taken into consideration and any other possible sources of weightlessness that triggers some key systems of the body to electricity will be explored and identified. relax as they no longer fight the pull of gravity compared to the Earth atmosphere. Because of that, people's sense of up and 3- Theoretical studies of the existing design of down gets confused. space station

From these problems, it can be specifically pinpointed that the negative effects arise due to weightlessness. The solution to decrease the effect of weightlessness in the space atmosphere will be studied while conducting this project. 2.4- Radiation

Humans living in Space will be exposed to harmful solar radiation due to the absence of the geomagnetic field that the Earth provides [3]. There are two types of solar radiation [3]; The first one is called Galactic Cosmic Radiation (GCR) which Stanford Torus (1975) Bernal Sphere (1928) is due to the continuous exposure of the sun’s radiation. And the second one is known as Solar Proton Events (SPE) which are solar flares with a huge concentration of radiation. There is actually a third type of solar radiation, which is particles that are trapped in the Earth’s magnetic field.

The type of radiation that is considered as dangerous is the SPE because it may cause death to humans when they are completely unprotected from the radiation [3]. This concludes that radiation in Space should be filtered. So, the solution to filter or to shield Elysium (2013) Space Station V (1968) Table 1: Design of the existing space station studied. against those harmful radiations will be identified in this Source [9] [10] [11] [12] project. The objective for this section is to review and study the

theoretical designs of some of the designs proposed for by the researchers and also two of the designs from 품 ω = √ some famous sci-fi movies. The existing design of space station 풓 that will be studied are: Then, we can obtain the rotation per minute (Ω) of the space a. Stanford Torus (1975) (existing theoretical design) habitat. Let Ω (capital Greek letter omega) be the rate of b. Bernal Sphere (1928) (existing theoretical design) rotation in rpm, we can use the following equation: c. “Elysium” Space Station, Elysium (2013) (film of science fiction) Ω = 9.55ω rpm d. “2001: Space Odyssey” Space Station, Space Station 4.2- Reducing Coriolis effect V (1968) (film of science fiction) In relation to the point above, creating for the For all of the existing design of the space stations studied, the space habitat will cause Coriolis force to act on the space main characteristic that will be studied are: habitat. “If a rotating habitat is being used to generate simulated • Design and the number of people can inhabit inside the gravity, Coriolis deflection can interfere with the performance space station of simple tasks and, at the extreme, generate motion sickness” • Artificial gravity and Coriolis effect [16]. The Coriolis effect will be greater if the rotational speed • Power source is faster. • Lighting system While humans have been shown to respond to speeds as high as • Cooling system 23 rpm, it is widely accepted that at 2 rpm or less, no adverse • Materials (Generally, not in-depth study) effects from Coriolis forces can occur [17]. As a conclusion from the studies, the goal when designing the space habitat is to 4- Elements in designing the space habitat ensure that the rotational speed (in rpm) or rotation per minute 4.1- Creating artificial gravity (Ω) of the space habitat is to be less than 2 rpm if possible.

The space habitat needs to rotate at a certain angular velocity 4.3- Power source based on its diameter to generate the artificial gravity. From the In this project, only the main power source will be determined. studies, it is concluded that an artificial gravity must be created The main power source for the space habitat will be solar similar or equal to the Earth’s gravity (Earth gravity = 9.8 m/s2 energy because the space habitat will be located in Space and [5]). This will result in humans able to live in space but in Earth solar energy will easily be obtained directly from the sun. Solar gravity, reducing the risk of humans getting the health issues array will be installed at the space habitat. First of all, we need that had been studied. If the diameter of each part of the space to know the total electrical power needed to power the whole habitat varies, each part must rotate at a different angular space habitat. After knowing the amount of electrical power velocity to attain the same artificial gravity. needed, we need to calculate the total size or area of solar array According to Gerard K. O’Neill, who is a physicist, he proposed needed to be able to supply the electrical power using the in an article “Space colonies and energy supply to the Earth” of formula [18]: a 1975 book, Science 190 [13] to use centrifugal force to create P = 푨 ∗ 푮 ∗ 휼 artificial gravity. This means that the application of centripetal force is required to generate artificial gravity. With the given equation, we could determine the area of the solar array and search for the most suitable one based from the list of the currently available solar array with a good efficiency if possible. The better the efficiency, the better the quality of the solar array. The chosen solar array will be equipped to the design of the space habitat.

Possible alternate power source

The option for using biomass energy to electrical energy as the power source has also been considered. The source of biomass

is from living things (or things that we once living) [19]. Human Figure 3: Illustration of applying centripetal force to create artificial feces, plants and crops too are considered as one of the sources gravity. Source [14] for biomass. Despite that, after a few studies on it, it is decided that Biomass energy as a power source will not be considered Since we are using centripetal force to create artificial gravity for the space habitat of this project. This is because it is found of Earth, the centripetal force generated by the space habitat that biomass energy is not suitable as a power source to power needs to be equal to the gravitational force. Therefore, the up a large-scale object like the space habitat for this project. The equations [15] that needed to be considered were as follows: heat and gas emission for the biomass process is high but the electrical power obtained from it is small [20]. Even though it Other than the characteristics stated above, there is also the can be suitable for generating electricity at a small-scale object, characteristic of long-span durability. Space habitat is built with the main objective for this subsection is to determine the main an objective of a very long duration of stay in deep space. power source as a whole for the entire part of the space habitat. Hence, when selecting materials for the space habitat, materials Therefore, it is not convenient to consider it a power source for with a long lifetime before breaking down must be taken into the space habitat of this project. account. 4.4- Lighting system In a nutshell, there are many factors of consideration when deciding the most suitable material for the space habitat. In “Light is clearly related to human biological functions, and reality, it will take more time and more testing and experiments therefore architecture has historically focused its efforts on to really determine the best material for this space habitat that providing both shelter and adequate lighting, giving its can meet all of the above criteria. Hence for this project, the residents a suitable place to perform their activities” [21]. From material for the construction of the space habitat will only be the previous statement, it is clear that the humans who did not suggested generally as this project primarily focuses on received lighting for more than a period of time may act designing the space habitat. differently due to their psychological behavior change and also may result to other health issues. Therefore, in the design of this 5- Design of the space habitat space habitat, giant mirrors will be equipped on it. The giant mirrors will aid to reflect the light throughout the roof or the In this section, the design of the space habitat for the project is ‘sky’ of the space habitat. Consequently, the humans will introduced. The shape of the space habitat is inspired from the experience natural lighting from the sun in the same way as they combination of all the studies that had been made in this project are when they are on Earth. on the existing design of the space station. As a conclusion for the design of the space habitat of the project, I decided to take 4.5- Thermal control system inspiration for the main component of the space habitat where the people are accommodated to be the shape of a torus (ring- One of the heat challenges for the design of this space habitat shaped). will be the constantly increasing of internal temperature from the heat-producing instrument such as the heat generated from Mainly, the objective for the ideas of my design is to be able to generating electricity, power consumption and excessive house far greater number of people in but at a smaller size in expose to sunlight. The basic solution for this is to install a heat comparison to other space station that had been studied in the exchanger device on the space habitat, or also known as space project which are the Stanford Torus, Bernal Sphere, Elysium radiators. and Space Station V

There will be a main radiator and several other small radiators All of the components of the design for the space habitat are installed on the space habitat such as on the wall. As this project done using NX12 Siemens PLM Software. The dimensions is only focused on the design of the space habitat, the detailed shown are in the unit of millimeter (mm) and the designs have part of how the radiator works and detailed studies of the a 1 mm : 10 m ratio. thermodynamics will not be explained here. Then, only the main radiator will be focused on during the design of the space 5.1- Overview design of the space habitat habitat. Radiator will exchange heat via radiation. In order to design the main radiator, we need determined how big the size of the radiator needed. Hence, we can use the radiation law of Stefan-Boltzmann formula:

4 4 P = σeA (T2 – T1 )

4.6- Material

In Space environment, all materials are subjected to extreme stresses in space, allowing only the most durable materials to survive [22]. There are a few characteristics that needs to be considered when choosing the right materials:

• Spiking of temperature • Radiation • Pressure • Impacts • Stress-strain capability Figure 4: Overall design of the space habitat. [own source]

axis, and 2 big solar panels at each end of the main pole aligned with the y-axis. 2 main radiators are built on the middle of the main pole indicated like figure 6 above aligned with the x-axis. All of these described components are built as a single main component. The secondary poles act as a connector for the main mirrors (not shown in the figure 6) with the main non-rotating pole.

Figure 5: Cross-sectional overview of the space habitat. [own source]

The place for the housing of the inhabitants is called the habitat ring. The space habitat has 4 habitat rings attached to a main non-rotating pole which is placed horizontally in space. The Figure 7: Dimension (mm) of the main-non rotating pole. (without space habitat will generate artificial gravity equal to the gravity the solar panels and radiator) (scale 1mm : 10 m) [own source] on Earth inside the space habitat by rotating at a certain angular velocity. Only these 4 habitat rings will be rotating and the rest The main diameter for the horizontal pole (or is situated in the of the component will stay stationary. These 4 habitat rings are y-axis according to figure 6) is 600 m and the vertical poles attached to a main non-rotating pole that is positioned situated at a distance of 175m from both end of the horizontal horizontally in space. Solar panels are equipped on the space pole has a diameter of 550 m each. habitat for generating electrical energy from solar energy received directly from the sun. Mirrors are attached on the space habitat for reflecting and redirecting the sunlight towards the habitat for natural lighting. And finally, radiators are built on the space habitat for helping and regulating the thermal control system of it. The mirrors, solar panels, and radiators are connected onto the space habitat with secondary poles which are attached on the main non-rotating pole and are considered as a single component.

Components of the space habitat Figure 8: Space shuttle dock’s gate. [own source]

In total, there are 19 components to build this space habitat; a Zooming in on the middle of the main non-rotating pole, are the main non-rotating pole, 4 habitat rings, 2 main mirrors (top and gates that act as the space shuttle dock/landing facility. The gate bottom), 4 small solar panels, 2 big solar panels, 2 radiators, and can be seen in the figure 8 above inside the red-colored circle. 4 ball bearings. This idea is inspired by both of the space stations from the science fiction movies that have been studied in this report, Elysium and Space Station V.

Figure 6: Main non-rotating pole. [own source] Figure 9: Cross-sectional view inside the space shuttle dock and The main non-rotating pole is the mother structure that holds all elevator tube. [own source] the components of the space habitat. It is equipped with 4 small The figure 9 above shows the inside of the space shuttle dock solar panels in the middle of the main pole aligned with the z- and the elevator tube. As the name suggested, the space shuttle dock will be the landing facility of the space shuttles inside the length and 5000 m of width. All part of the mirror will reflect space habitat and the elevator tube will help and transport the the sunlight towards the secondary inner mirror of the habitat people from the space shuttle dock to any of the habitat rings. for them to redirect the sunlight towards the habitat ring. Each of the mirror will have an area of 60 x 106 m2 to reflect the The 2 big solar panels located at each end of the main non - sunlight towards the space habitat. rotating pole will have a length of 4000 m (4 km) and a width of 2000 m (2 km), resulting of an area of 8 x 106 m2 each that will face the sun. The 4 small solar panels however, have a length of 4000 m (4 km) and a width of 400 m which results and area of 1.6 x 106 m2 each that will face towards the sun.

For the dimensions of the radiators attached on the main pole, each of them has a dimension of 3000 m (3 km) of length and 3000 m (3 km) of width. Each of the radiators will have an area of 9 x 106 m2 to release the heat from the space habitat away to the outer space.

Figure 13: Bearing and its ball bearing separator. [own source] Figure 10: Habitat rings. [own source] The rotation of the space habitat is supported with bearings which are positioned between the component of the main non- rotating pole and the inner ring of the habitat ring. The ball bearing separator acts to hold all the ball bearings inside and also functions to prevent the ball bearings from touching and colliding with each other to reduce friction. The type of bearing that is used for this space habitat will be a sealed-type bearing, so a bearing cover will be placed on the bearing and can be seen in the figure 13 above. The reason to use the sealed-type is to prevent the ball bearings inside from any debris and also to keep Figure 11: Cross-sectional view of the habitat ring. the lubricant trapped inside as in the Space environment, an (scale 1mm : 10 m) [own source] open-type bearings may cause inconvenience for the lubricant There are 4 habitat rings built for the space habitat. All 4 of the to flow out of the bearing. space habitats have the same diameter of 8000 m (8 km) from one end to the other end. However, the diameter from the floor 5.2- Artificial gravity and the Coriolis effect of of the habitat from one end to the other end is only 7620 m the space habitat (7.62km). The habitat rings are the place for all of the To create artificial gravity inside the space habitat, the space inhabitants to live in inside the space habitat. In the inner part habitat needs to rotate at a certain angular speed. Hence, we of the ring is equipped with secondary inner mirrors with an need to calculate the angular velocity (ω) of the habitat ring. It angle of 45° for the lighting system of the space habitat. The consists of 4 habitat rings with the same size and diameter. secondary inner mirrors will redirect the sunlight that have From that, we know that the angular velocity for all four of the reflected by the main mirrors towards all parts of the habitat. habitat rings will be the same.

All of the habitat rings have the same diameter of 8000 m (8 km) from the center of the axis to the end of the ring. However, the diameter required for the calculation is the diameter from the center of the axis to the floor of the habitat ring. The diameter for it is 7620 m (7.62 km). Hence, the radius will be 3810 m (3.81 km) Figure 12: Main mirrors. [own source] In order to for the habitat ring to achieve and produce an The two main mirrors will be attached to the top and bottom of artificial gravity similar to earth which is 9.81 ms-1, it needs to the main non-rotating pole connected with the secondary poles. have an angular velocity (ω) of: Each of the mirror has a dimension of 12 000 m (12 km) of

ퟗ.ퟖퟏ 풎풔−ퟐ ω = √ ퟑퟖퟏퟎ 풎

ω ≈ 0.05074 rad s-1

Next, is the determination of the Coriolis effect for the space habitat. The Coriolis Effect needs to be identified so that we can conclude whether the space habitat is habitable for the humans on Earth able to live comfortably in it. one of the objectives for designing the space habitat is to have a Coriolis Effect less than 2 rpm. It can be determined by calculating the rotation per minute (Ω) of the space habitat. Figure 14: Top view of the space habitat (without top mirror) to With the value angular velocity (ω) obtained above, the rotation show direction of rotation of the habitat rings. [own source] per minute for each of the habitat ring will be: Through the figure 14, habitat ring 1 and 3 rotate on the same Ω = 9.55(0.05074 rad s-1) rpm aligned axis while habitat ring 2 and 4 rotate on the same aligned axis with each other but different that the aligned axis Ω = 0.484567 rpm of habitat ring 1 and 3. However, all of them rotate on the same main pole which is non-rotating. So, habitat ring 1 and 3 rotate The value is less than 2 rpm. Therefore, it meets the requirement in clockwise direction while habitat ring 2 and 4 rotate in anti- and can be concluded that the habitat ring is habitable for clockwise direction. This combination of the direction of humans on Earth to be able to live with comfort in it. rotation will results in balancing out each other angular 5.3- Conservation of angular momentum momentum hence resulting the total angular momentum will be L = 0. This can be proved with the equation below: As the space habitat will be rotating, this will result in creating angular momentum (L). Usually on Earth in an open system, L = I x ω there will be external force or torque that may disrupt the To calculate the moment of inertia of the habitat ring, the angular momentum of any object. However, in space equation of I that will be used is the moment of inertia of a disc environment, it can be considered as a closed system. This with respect to its center: means that the angular momentum will be conserved. The ퟏ reason is that because there is no air in space, hence there is no I = MR2 ퟐ air resistance [23]. And external torque will in an environment usually refers to gravity. Again, it is considered as no gravity in The I for all the habitat rings would be considered the same as space environment. Gravity do presence in space; however, it they all have the same radius and the mass for all the habitat decreases with the increasing distance from a planet or star [23]. rings to be the same. Therefore, I = I1 = I2 = I3 = I4. Considering As the space habitat will be position a distant way that can be clockwise direction as positive and anti-clockwise direction as considered as far away from Earth, it will be considered as no negative; gravity and negligible. Thus, supporting the fact that the angular -1 -1 momentum will be conserved. L Total = (I ∗ 0.05074 rad s ) + (I ∗ -0.05074 rad s ) + (I ∗ 0.05074 rad s-1) + (I ∗ -0.05074 rad s-1) As stated in the previous sub-section (refer section 5.1), the rotating system for this space habitat is supported by a bearing L Total = 0 system with a sealed-type bearing. Hence again, it is to 5.4- Estimation of population inside the space eliminate any external force or friction acted on the rotating system of the space habitat, therefore making me consider it to habitat be negligible. From these reasons, it can be concluded that the The area of the habitat needs to be calculated. angular momentum for the space habitat will be conserved. It means that once the space habitat starts to rotate, it will continue to rotate with the same angular velocity and angular momentum.

However, there are 4 habitat rings that will be rotating for the space habitat and all of them need to be rotating at a certain angular velocity and at a certain direction. This is to ensure the angular momentum for the 4 habitat rings to balance out each other and to keep the space habitat at the exact same position Figure 15: Area of inhabitable area dimensions (mm). and location in space. (scale 1mm : 10 m) [own source]

To obtain the area of the habitat, the formula for the lateral (side) surface area of the cylinder is used. The reason for using this equation is because a torus-shaped is nothing more than a rolled cylinder. Hence the following formula will be use:

A cylinder = 2πrh

For this situation, r is the radius of the torus from the floor of the habitat to the center and h is the length of the floor of the habitat. Therefore, the area of the habitat can be obtained.

Before calculating, I assume and consider that the entire interior surface of the torus is habitable. Figure 16: Diagram of the Lagrange points associated with the sun-Earth system. Source [25] A = 5715000 π m2 “A is a location in space where the combined As all four of the habitat rings have the same size, the total area gravitational forces of two large bodies, such as Earth and the for the habitat will be: sun or Earth and the , equal the centrifugal force felt by a much smaller third body. The interaction of the forces creates a Total A = 22 860 000 π m2 ≈ 7.18 x 107 m2 point of equilibrium where a may be "parked" to Next will be the calculation and estimation of population inside make observations” [25]. In simple words, these Lagrange the space habitat. Theoretically, there is not any exact and only points or also known as libration points can be used for any way to estimate the population at a certain place. As the design spacecraft to be positioned there to remain in a stationary of this project can be categorized as a general concept and not position. a detailed one, the estimation of population can mostly be based According to the figure 16 above, there are 5 Lagrange points on the area of land. which are L1, L2, L3, L4 and L5. It is found that 3 out of the 5 For this design, I decided to estimate the population inside the points are considered as unstable points [25]. These points are space habitat based on the data of the population density in L1, L2 and L3. Any spacecraft that is located at these points Singapore as a reference. Based on Our World in Data [24], still needs to make a bit of an adjustment to maintain their Singapore has a population density of nearly 8000 people/km2. trajectory despite being “parked” there. The remaining points, This is due to the fact that the country has a small land. From L4 and L5 are considered stable. Therefore, any spacecraft this data, it also actually proves that a large number of people located at those points, will not have to do anything to maintain can be accommodated in a small area. Therefore, this data can their trajectory and position. As a conclusion from this study, be used and will be used in this project for the estimation of L4 and L5 will be the good position for the space habitat of this population inside the space habitat. project to be located on.

Given that the population density of 8000 people/km2 and the 5.6- Lighting system area of the space habitat that has been calculated above, the estimation of population inside the space habitat will be: The space habitat will be located either in L4 or L5 so that it can stay locked in a position in Space. Therefore, the space ퟖퟎퟎퟎ 풑풆풐풑풍풆 ퟏ 풌풎ퟐ ∗ ∗ 7.18 ∗ 107 m2 = 574 400 people habitat will continuously be supplied by a maximum amount of 풌풎ퟐ ퟏ ퟎퟎퟎ ퟎퟎퟎ 풎ퟐ natural sunlight. one of the objectives when designing this space habitat to be The lighting system method that will be used by this space able to accommodate a large number of people. And from the habitat is by using the principle of reflection of light. This calculated data above on the population for this space habitat, it method has widely been used since the early days of proposing can be concluded that this design of the space habitat has a space habitat. The space habitats that have been studied in this achieved its objective as 574 400 people is a large number of report such as Stanford Torus and Bernal Sphere too have been people. using this method to redirect the sunlight from the sun to its 5.5- Position of the space habitat in space habitat.

From the study, what I understood from it is that it is important to determine the location or the position on where to put the space habitat in Space. And Lagrange point or also known as parking places in space is the answer for it.

To calculate the electrical consumption per capita in Watt [W], the following formula [27] will be used:

Electric power per capita [W] = Total population- electricity 풌푾풉 ퟎ.ퟏퟏퟒퟎퟕퟕퟏퟏퟔ consumption [ ] ∗ 풚풆풂풓 풑풐풑풖풍풂풕풊풐풏

풌푾풉 Electric power per capita [W] = 50 409 ∗ 0.114077116 풚풆풂풓

Electric power per capita [W] ≈ 5750 W

As the space habitat able to fit approximately 574 400 people, the minimum power required for the space habitat will be:

P Min = 5750 W per capita ∗ 574 400 people

9 P Min ≈ 3.3028 ∗ 10 W

Now as we done calculating the minimum power required for

the space habitat, we can calculate the total power that will be Figure 17: Diagram showing the reflection of the sunlight towards generated by the solar array for the space habitat. the habitat rings. [own source] P = 푨 ∗ 푮 ∗ 휼 All of the mirrors equipped on this space habitat are built or placed at an angle of 45°. The sunlight first will shine G referring to solar irradiance or can be known as solar horizontally towards the top and bottom main mirror of the radiation intensity (Ho) can be calculated using the formula space habitat. Then, the top and bottom main mirrors will below: redirect the sunlight vertically towards the inner mirrors of each ퟐ 푹풔풖풏 habitat ring; habitat ring 1, habitat ring 2, habitat ring 3 and Ho = ∗ H sun 푫ퟐ habitat ring 4. Top main mirror will redirect the sunlight 6 푊 vertically downward towards habitat ring 1 and 2 while the According to the source [28], H sun is 64 x 10 and R sun is 푚2 bottom main mirror will redirect sunlight vertically upward 695 x 106 m. D2 will be the distance from the sun to the space towards habitat ring 3 and habitat ring 4. From there, the habitat at L4 or L5. Both of the points have the same distance redirected sunlight from the main mirrors will pass through the from the sun as the points are vertically above and below each secondary mirrors which are attached at the inner part of other (refer figure 53). For the distance from L5 or L4 to the respective habitat rings and again will reflect the sunlight. The sun, there has been any actual facts or data on it. But referring sunlight will finally be reflected horizontally outward towards to figure 53, I assumed that the distance of L4 and L5 from the the ceiling or sky of the habitat rings and as a result, all parts of sun is the same as the distance from the sun to the Earth which the habitat ring will receive sunlight. is 149 597 870 700 m [28]. So, the Solar radiation density will 5.7- Calculating power source be: ퟔ ퟐ (ퟔퟗퟓ 풙 ퟏퟎ 풎) 6 푾 푾 Ho = ∗ 64 ∗ 10 ≈ 1381 The space habitat will use solar energy as the main power (ퟏퟒퟗ ퟓퟗퟕ ퟖퟕퟎ ퟕퟎퟎ 풎)ퟐ 풎ퟐ 풎ퟐ source for the whole system. Therefore, solar arrays will be equipped on the space habitat again like stated in section 4.3. For the solar panel efficiency, the space habitat will use solar The solar array consists of 2 big solar panels equipped at the panels that have the highest efficiency right now in the market. side of the space habitat respectively and four small solar panels According to the source [29], the highest solar panel efficiency and are equipped at the middle of the space habitat on the main out there is 22.6% made by the manufacturer, SUNPOWER. non-rotating pole. The two big solar panels attached on the side of the space 6 2 To determine the minimum power required for the space habitat has A = 8 x 10 m each while the four solar panels 6 2 habitat, we need to know the average power or electricity used attached on the middle of the space habitat has A = 1.6 x 10 m per capita (person). According to the source [26], the average each. With all of these data are known, the total power electricity use per capita varies depending on the country. I generated by the solar array of the space can be calculated. decided to use the data from Iceland which is the largest 6 6 2 푾 P Total = ((2 ∗ 8 ∗ 10 ) + (4 ∗ 1.6 ∗ 10 )) m ∗ 1381 ∗ 0.226 electrical consumption use per capita in the world to calculate 풎ퟐ the minimum power required for the space habitat which is 50 9 9 P Total = 6.991 ∗ 10 W > P Min = 3.3028 ∗ 10 W 409 kWh/year. The reason I chose to use that data is for safety measures to ensure that there will still be extra power available in case of any emergency cases.

The total power generated by the solar array will be excessively would only suggest the common materials that have currently enough. Hence, the objective for this sub-section is achieved. been used by most of the spacecraft that have been launched out there. 5.8- Calculating thermal control requirement For all the body parts or most parts of the space habitat will There will be a constant increase of internal temperature which consist of aluminum alloy. The factor due to its light weight is is the temperature inside the space habitat due to exposure to a major reason to be chosen as the material for the space habitat. sunlight, power consumption and also from human bodies. Aluminum itself is not that strong and tough. However, the Therefore, building a space radiator is the solution to get rid of weakness of it can be overcome by combining with other metals the excess heat from the closed system in the space habitat into to form an alloy with increasing features of strength and space. There will be two big radiators equipped on the space hardness while retaining its lightweight. habitat (refer figure) The outer layer of the aluminum alloy will be covered by An average person dissipates about 8.37 x 106 Joules per day Kevlar. It is lightweight but a very durable material, making it which is roughly around 100 W [30]. As a safety measure, I able to withstand strong impact and can support aluminum alloy would assume it to be a little bit higher around 150 W so that to withstand the weight of the large number of inhabitants in it. the size of the radiator can dissipate more heat than the normal It can retain its original shape while in high temperature. Thus, amount in case of any unfavorable condition. Therefore, the making it perfect as an outer layer to cover the aluminum alloy. total amount of heat release by a total of 574 400 people will 7 be, P People = 8.616 x 10 W. The material both for the habitat ceiling and the mirrors for the space habitat will be made from thermal glass. Thermal glass is The amount of heat dissipated by the radiator can be calculated used for spacecraft due to its characteristic ability to endure using the equation suggested from the sub-section 4.5 extreme heat from hot to cold. Despite that, it also has a good

4 4 pressure resistance. One of the concerns when assigning the P = σeA (T2 – T1 ) materials for the space habitat based on the materials from the 푾 σ= Stefan-Boltzmann constant = 5.67 ∗ 10-8 existing spacecraft is that, most of the spacecraft out there are 풎ퟐ푲ퟒ built for mission purpose and the number of people can e= 1 (assuming black body) accommodate inside it is very small. Given that this space habitat is to house 574 400 people, in my opinion, the materials The value for T1 = 27 °C (300K), which is at room temperature assigned might not be the most appropriate as it may need and is assumed to be the temperature of the space habitat. For sturdier materials. the temperature of space which in the space habitat case, will be at L4 or L5. At the moment, again there has not been any 6- Comparison actual facts or data on the temperature at L4 or L5. So, I decided to take the average temperature in Space which, according to Referring to table 2 below, it is found that the biggest advantage of this design is that it can fit a huge number of people in it the source [31], it is about 2.7 K. Therefore, the value for T2 = 2.7 K. Last but not least, the for the two radiators, A = 9 x 106 despite being quite small in the size of the habitat based on the m2 each. comparison of the design of the project compared to the four other designs that have been studied throughout the project. It Finally, the amount of heat dissipated by the radiators can be can be deduced that the project’s design is the most efficient in calculated. design to accommodate people. The project’s design also has a quite small angular velocity and a low Coriolis effect, resulting 4 4 P = σeA (T2 – T1 ) in the people living inside the space habitat will experience only P ≈ - 8.267 ∗ 109 W a minimal Coriolis effect and will not endanger their life.

(Negative sign indicate it is releasing heat)

9 7 P Radiator = 8.267 ∗ 10 W > P people = 8.616 ∗ 10 W

This proof that the size of the radiators built onto the space habitat meets the requirement for the thermal control and hence, achieved the objection for this sub-section. 5.9- Material for the space habitat

For this project, only a general election of materials for the space habitat is done. This is because multiple testing and more thorough studying of material needs to be done to finally pinpoint the perfect material for the space habitat. Therefore, I

4. The habitat rings will rotate at an angular velocity of 0.05074 rad s-1 to create an artificial gravity similar to the Earth environment. 5. The habitat ring will experience a minimum Coriolis effect with a rotation per minute of 0.484567 rpm. 6. The 4 habitat rings have the capacity to house a total of 574 400 people altogether. 7. Habitat ring 1 and 3 will counter rotate with habitat ring 2 and 4 so that the angular momentum is conserved. 8. The space habitat will be located either in L4 or L5 in space. 9. The space habitat’s lighting system will be using the principle of reflection of light with mirrors attached on it to redirect the sunlight towards the habitat rings. 10. The solar panel efficiency for the space habitat will be 22.6%. The total electrical power generated from the solar panel is more than the minimal power required for the space habitat. 11. The radiators have the capability to release heat to the environment which exceed the total heat release by the people inside the space habitat. 12. There is not an accurate assignation of materials for the components of the space habitat of this project.

There may be some parts lacking in my design and further research and study is needed. Here are some suggestions of improvement that can be made in the future for any further studies and researches on this project:

1. Further research for the viability of Biomass as the main power source. 2. Further research on the other alternate energy source to become the main power source of the space habitat. 3. Further material testing and research on the materials available to determine the most suitable and perfect material for the space habitat. Table 2: Comparison for each of the Space Station that have been 4. Further research on the actual distance of L4 and L5 studied with the design of the space habitat of this project. from the sun and discover the resources available there [own source] for the use of the space habitat. 7- Conclusion & suggestions of improvement 5. Analyze other possible spatial locations and orbits for the orbital station. As a conclusion, I will be summarizing all the main points 6. Discover and determine the appropriate way to initiate regarding the alternative design of the space habitat for this the construction of the space habitat whether build it project. on Earth and launch it to Space or just build it in Space. 1. The main design for the housing of the habitat is a Acknowledgement shape of a torus (ring-shaped) inspired by the design of the Stanford Torus. I would like to express my greatest gratitude to my project’s 2. The components of the space habitat consist of a main supervisor for my TFG, Manuel Moreno Lupiañez for the non-rotating pole, 4 habitat rings, 4 ball bearings (with continuous guidance throughout my project. He has been ball bearing’s separator), and 2 main mirrors. The helping me to do my TFG. Any doubt or report on the main non-rotating pole is equipped with 2 radiators, 2 progression of my project, he will surely help and review it as big solar panels, 4 small solar panels. fast and informative as possible. I also want to take this chance 3. Only the habitat rings, will be rotating while the other to express my gratitude to all the researchers, physicists, components will remain stationary at a position. bloggers and others relating to those that publish and provide their research papers, books, and articles regarding the topics that are related to my project to design a space habitat. Other than that, I would also like to express my gratitude to my family [17] H. Hecht, E. L. Brown and L. R. Young, "Adapting to artificial members who are very far away from Spain in Malaysia and gravity (AG) at high rotational speeds," In: Proceedings of "Life in also to my friends. They have indirectly provided me with space for life on Earth". 8th European Symposium on Life Sciences Research in Space. 23rd Annual International Gravitational emotional support. 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