13 Appendix: City Infrastructure Table of Contents 13 Appendix: City Infrastructure .......................................................................................... 491 13.1 Apartment Layout ........................................................................................................ 495 13.1.1 Railroad Platform Area ......................................................................................... 497 13.2 Lighting ........................................................................................................................ 499 13.3 Rock Bolting ................................................................................................................ 501 13.4 Pressure Bulkheads ...................................................................................................... 503 13.5 Housing Frames............................................................................................................ 504 13.6 Housing Exteriors ......................................................................................................... 508 13.7 Reactor Buildings ......................................................................................................... 509 13.8 Uniform Pressure Loading ........................................................................................... 510 13.9 Material Properties ....................................................................................................... 513 13.10 Mass of Primary Structural Elements ....................................................................... 514 13.11 Alternative Power Designs ....................................................................................... 515 13.11.1 Geothermal Plant ............................................................................................... 515 13.11.2 Drilling on Mars ................................................................................................ 515 13.11.3 The Process of Building a Geothermal Plant on Mars ...................................... 516 13.11.4 Steam Cycle....................................................................................................... 518 13.12 Other Options Considered for Power ....................................................................... 519 13.13 Nuclear Reactor Design Rationale ........................................................................... 521 13.14 Reactor Lifecycle Management ................................................................................ 523 13.15 Personnel .................................................................................................................. 524 13.16 Alternate Reactor Designs and Proliferation Concerns ............................................ 525 13.17 Power Distribution .................................................................................................... 527 13.17.1 The Need ........................................................................................................... 527 13.17.2 Power Lines ....................................................................................................... 527 13.17.3 Transformers [42] [43] ...................................................................................... 530 13.17.4 Overhead Power Lines in the City [44] ............................................................. 531 13.17.5 Power Lines Vs Localized Power Systems ....................................................... 532 13.17.6 Why High Voltage Lines [46] ........................................................................... 536 13.17.7 Totals ................................................................................................................. 537 Purdue University | Project Future Mars 491 13.18 Lava Tube Pressurization ......................................................................................... 539 13.18.1 Introduction ....................................................................................................... 539 13.18.2 Pressurization Trade Study................................................................................ 539 13.18.3 Pressure Loss ..................................................................................................... 541 13.18.4 Transferring Heat from Air to Water ................................................................ 542 13.19 Initial Lava Tube Sizing and Location ..................................................................... 543 13.19.1 Initial Location on Olympus Mons ................................................................... 543 13.19.2 Initial Size ......................................................................................................... 544 13.19.3 Creating Modules .............................................................................................. 545 13.19.4 Summary of Considerations .............................................................................. 546 13.20 Water Recycling ....................................................................................................... 547 13.20.1 Introduction ....................................................................................................... 547 13.20.2 Existing Technology ......................................................................................... 547 13.20.3 Design Considerations....................................................................................... 549 13.20.4 Risk Assessment and Lifecycle Considerations ................................................ 550 13.20.5 Activated Carbon Process ................................................................................. 553 13.21 Fecal and Urine Nutrient Recycling ......................................................................... 555 13.21.1 Solid Waste Management.................................................................................. 555 13.21.2 Initial Urine Processing and Nutrient Recovery ............................................... 557 13.22 City Lighting Trade Study and Possible Design ...................................................... 559 13.23 Sizing and Power Estimates for Necessary City Buildings ...................................... 562 13.24 Calculating Pressure and Heat needed within the Lava Tubes ................................. 563 13.25 Heat Loss from Lava Tube to Surroundings ............................................................ 565 13.26 References ................................................................................................................ 567 Purdue University | Project Future Mars 492 Nomenclature l Lux, J/m2 x c Coefficient of beam utilization, unitless bu l Lumens, J m a floor area of city, m2 Pw power needed per streetlight, W Pt power needed for all fixtures, kW d distance between streetlight, m h height of lava tube module, m w width of lava tube module, m l length of lava tube module, m v volume of lava tube module, m3 r specific gas constant, J/mol-K p pressure, Pa T temperature inside lava tube, K t T average surface temperature on Mars, K m ΔT temperature difference between lava tube and Mars surface, K M molar mass, kg/mol n moles of gas v total volume of gas, m3 g v volume for 1 kg of air, kg/m3 s v ratio of moles of gas to total moles of air r m mass of gas, kg c specific heat, kJ/kg-K p q heat energy, kJ h = height, m l = length, m p = 1.6075, constant used to find surface area of an ellipsoid s = surface area of half ellipsoid, m2 e s = surface area of floor, m2 f Purdue University | Project Future Mars City Infrastructure | 493 r = radius of rock bolt, m a l = length of rock bolt, m r d = rock bolt placement density, 1/m2 r s = surface area of rock bolt, m2 r ΔT = temperature difference between lava tube and Martian regolith q = heat loss, MW loss Purdue University | Project Future Mars City Infrastructure | 494 13.1 Apartment Layout Before determining an aesthetic-looking city layout, we must first determine the number of apartment buildings needed to house 10,000 in two modules. We have stated our assumption that each housing module has about half of the city’s population, while also leaving room for potential expansion. We also know that every building cannot share the same height because of the curve of the lava tube ceiling, as seen in Figure 13.1. Since the lava tube is a semi-ellipse, each column of buildings has a different height from one another. Figure 13.1: The buildings in the lava tube all have different heights. Figure 13.1 show that we decided to place nine columns of buildings, each column with a different height based on its location along the width of the lava tube. For example, the tallest building is 66 m tall, while the shortest building (excluding the communications site) is 9 m tall. We agreed that apartments should have as many floors as possible to house as many people as possible, so we decided that the majority of the residents live in the taller buildings. Excluding truss buildings, the apartment building heights are 13 m, 54 m, 63 m, and 66 m. Table 13.1 shows the number of buildings corresponding to each height. Purdue University | Project Future Mars S. Raman | 495 Table 13.1: Number of apartment buildings for each height. Floors # of Apartment Buildings 13 7 18 10 20 4 21 8 22 8 TOTAL: 37 The four truss buildings are located relatively in the same area as the 63-m tall buildings. However, since we need room for science labs, food storage, and general office space, we only use 20 floors in each truss building. Assuming a floor height of 2.75 m, we can calculate the number of floors in each regular apartment building using: Equation 13.1 𝒃𝒖𝒊𝒍𝒅𝒊𝒏𝒈 𝒉𝒆𝒊𝒈𝒉𝒕 # 𝒐𝒇 𝒇𝒍𝒐𝒐𝒓𝒔= 𝒇𝒍𝒐𝒐𝒓 𝒉𝒆𝒊𝒈𝒉𝒕 We also assume that each person living in the city has a HAB volume of 100 m3/person. We use the HAB volume to calculate the maximum number of people living on each floor using: Equation 13.2 𝑭𝒍𝒐𝒐𝒓 𝒂𝒓𝒆𝒂 𝑴𝒂𝒙 # 𝒐𝒇𝒑𝒆𝒐𝒑𝒍𝒆 𝒐𝒏 𝒆𝒂𝒄𝒉 𝒇𝒍𝒐𝒐𝒓= × 𝒇𝒍𝒐𝒐𝒓 𝒉𝒆𝒊𝒈𝒉𝒕 𝑯𝑨𝑩 𝒗𝒐𝒍𝒖𝒎𝒆 Using Equation 13.2 we find that a maximum of 12 people can live on each floor. Then, we find the number of apartments needed per floor using: Purdue University | Project Future Mars S. Raman | 496 Equation 13.3 𝑭𝒍𝒐𝒐𝒓 𝒂𝒓𝒆𝒂 # 𝒐𝒇 𝒂𝒑𝒂𝒓𝒕𝒎𝒆𝒏𝒕𝒔 𝒐𝒏 𝒆𝒂𝒄𝒉 𝒇𝒍𝒐𝒐𝒓= 𝑨𝒑𝒂𝒓𝒕𝒎𝒆𝒏𝒕 𝒂𝒓𝒆𝒂 Equation 13.3 indicates that we can fit five apartments per floor. However, it does not take into account the space needed for stairs, a freight elevator, a laundry room, hallway space, and lobby space. Therefore, we only include four apartments per floor. Using the values obtained by both Equation 13.2 and Equation 13.3, we then find that each apartment can contain a maximum of three people. However, in order to find the maximum number of apartment buildings and account for expansion within the city, we set the requirement that each person have at least one housemate. Therefore, the number of people on each floor ranges from 8 to 12 people, but for the purposes of determining the maximum number of buildings, we only consider eight people per floor. This requirement also adds additional comfort to the residents’ living experience. Finally, we determine the number of people in each apartment building using the values in Table 13.1 and Equation 13.4. Equation 13.4 𝒑𝒆𝒐𝒑𝒍𝒆 𝒑𝒆𝒐𝒑𝒍𝒆 # 𝒐𝒇 = # 𝒐𝒇 𝒃𝒖𝒊𝒍𝒅𝒊𝒏𝒈𝒔 × # 𝒐𝒇 ×𝒏𝒖𝒎𝒃𝒆𝒓 𝒐𝒇 𝒇𝒍𝒐𝒐𝒓𝒔 𝒃𝒖𝒊𝒍𝒅𝒊𝒏𝒈 𝒇𝒍𝒐𝒐𝒓 The final results are shown in Chapter 4 of the main report. 13.1.1 Railroad Platform Area In order to include a railroad, we must first consider the amount of space required for the platform. We use Equation 13.5 to calculate the minimum required railroad platform area [5]. Equation 13.5 𝒔𝒑𝒂𝒄𝒆 𝒎𝒂𝒙.𝒑𝒍𝒂𝒕𝒇𝒐𝒓𝒎 𝒂𝒓𝒆𝒂= 𝒅𝒆𝒔𝒊𝒈𝒏 𝒑𝒐𝒑𝒖𝒍𝒂𝒕𝒊𝒐𝒏 ×𝒎𝒊𝒏.𝒑𝒍𝒂𝒕𝒇𝒐𝒓𝒎 𝒑𝒆𝒓𝒔𝒐𝒏 Purdue University | Project Future Mars S. Raman | 497 We consider the design population to be equal to the number of people living in the entire city. The maximum platform space per person is equal to 1 m2/person. Using Equation 13.5 we find that the total required platform area is 10,000 m2. We know that the distance from the edge of the aeroponics building to the edge of the concrete layer is about 8 m on either side. We also know that the width of the railroad is about 4 m, and by placing the railroad about 1 m away from the edge of the concrete layer, we have about 4 m left for the platform width in the city modules. We use this measurement for the other modules as well. Using 300 m as the length of each module, we can determine the actual platform area using Equation 13.6. Equation 13.6 𝒂𝒄𝒕𝒖𝒂𝒍 𝒑𝒍𝒂𝒕𝒇𝒐𝒓𝒎 𝒂𝒓𝒆𝒂 = 𝒑𝒍𝒂𝒕𝒇𝒐𝒓𝒎 𝒘𝒊𝒅𝒕𝒉×𝒍𝒆𝒏𝒈𝒕𝒉 𝒐𝒇 𝒎𝒐𝒅𝒖𝒍𝒆×# 𝒐𝒇 𝒎𝒐𝒅𝒖𝒍𝒆𝒔 We find that the actual total platform area is 4,000 m2, which is less than the maximum required platform area. Therefore, the design of the railroad is feasible. . Purdue University | Project Future Mars S. Raman | 498 13.2 Lighting Section 5.5.3 addresses high-efficiency, sustainable lighting technologies manufacturable on Mars. The sulfur plasma lamp is the only technology available capable of high levels of illumination efficiently. Based on the Food Production lighting appendix, we use the Ceravision ionCORE Light Engine and the Plasma International Plasma-i AS1300 Light Engines as model lighting systems. The ionCORE provides 26,000 Lumens and requires 400 Watts, and the Plasma- i AS1300 provides 163,000 Lumens and requires 1360 Watts [9][30]. We very roughly approximate the Ceravision ionCORE as being composed of 200 g of copper and 1.7 kg of aluminum, with a 1 g calcium oxide thermionic emitter for the magnetron. We assume the ionCORE uses the same bulb as the Plasma-i AS1300, already documented in the Food Production lighting appendix, each consisting of 9.4 g of fused quartz, 26 mg of sulfur, 2.78 mg of argon. Light output for human applications are measured in units of Lumens, which is based on the sensitivity of the human eye to different wavelengths of light, and is a measurement of the total quantity of light emitted from the source [31]. For measurements of the quality of lighting in an area, units of Lumens/m2, or Lux, are used instead. We base our lighting requirements on a table provided by the document “Recommended Light Levels (Illuminance) for Outdoor and Indoor Venues”, written by the National Optical Astronomy Organization as part of an educational package, reproduced in Table 13.2[10]. Based on Table 13.2, we have opted to have a 100 Lux minimum public lighting throughout the city and to provide on the order of 700 Lux throughout the day, to provide on the order of 200 Lux to housing, 500 Lux to offices, gyms, and laboratories, 750 Lux to heavy industrial workshops, 1,000 Lux to detailed machining and fabrication workshops, and 1,500 Lux to the Vehicle Assembly Building. To calculate the number of lamps for any given area, we divide the lamp output in Lumens by the necessary Lux for each area, producing the area illuminated by each lamp. Then, we divide the total floor space for each area by the area illuminated by each lamp to find the number of lamps necessary. Purdue University | Project Future Mars M. Prymek | 499 Table 13.2: Suggested illumination for various activities [10]. System Lux Public areas with dark surroundings 20 - 50 Simple orientation for short visits 50 - 100 Working areas where visual tasks are only occasionally performed 100 - 150 Warehouses, homes, theaters, archives 150 Easy office work, classes 250 Normal office work, PC work, study library, groceries, show rooms, 500 laboratories Normal drawing work, detailed mechanical workshops, operation theatres 750 Detailed drawing work, very detailed mechanical works 1,000 Performance of visual tasks of low contrast and very small size for 1,500 – 2,000 prolonged periods of time Performance of very prolonged and exacting visual tasks 2,000 – 5,000 Performance of very special visual tasks of extremely low contrast 10,000 – 20,000 and small size Purdue University | Project Future Mars M. Prymek | 500