Design Processes: A Moon Base Habitat Concept Design For Students and Arm Chair Astronauts A teacher’s guide for the study of ‘Design Processes’ for high school students and arm chair astronauts using a moon base Hab design as inspiration. David Willson - NASA Ames/KISS institute of Practical Robotics david. willson@nasa. gov Mark Gargano - Mars Society Australia, Education Officer Source: Wiley J Larson and Linda K Pranke, “Human Space Flight, Mission analysis and design”
Overview • Design Processes – Traditional Design Process and Concurrent Engineering Process – Concept Development Process & Team work – Generation of Ideas • Design Example: Design an Accommodation Hab for a Moon Base – Define the project aims, scope of work and technical specification – Define the Assumptions – Concept • Estimate the volume and define a geometry/shape Define the Structure • Estimate the supplies and equipment • Estimate the power needs. – Risk Assessment - Concept Design
(1) Traditional (sequential) Design Process Develop a Very Detailed Concept Various Design disciplines Detailed Design process – long time & lots of errors Various Design disciplines War Room Finished Product Develop a Rough Concept Finished Product Design Processes Detailed Design process – shorter time, less errors (2) Concurrent (parallel) Engineering Design Process (How the Japanese out-competed US and European Car Manufacturers: “Kim B. Clark, Takahiro Fujimoto “Product Development Performance” Harvard Business School)
Concept Design Process & Design Teams Concept Design Process Design Teams (1950’s-60’s & Today) Mission statement or general aim, Scope of work and technical specifications/data Various Technical Specialists Aims - Specification List Assumptions Drawing Board Develop Concept Vendor Equipment Assess risks & Check that Aims or general specification are satisfied Detailed Concept Detailed Design Marketing Information Design Teams (1970’s & 80 s) Aims - Specification Vendor Equipment Technical Specialist(s) or Manager(s) Drawing Board Marketing Information
How do we generate new ideas? (Where do they come from? ) - Understand the ‘core’ of the problem as best possible before developing a new idea. - One technique is to empty the mind of pre-conceived notions and sketch out thoughts and associations as they come regardless of their impracticality. A new idea can be generated from these thoughts. - Look at the work of artists and science fiction writers. Their ideas may not be workable but can inspire and generate new ones. - Bounce ideas of others. Allow others to add and change. Let the ‘team’ develop the idea. This requires good teamwork. An individual cannot know more than the team.
Design Example: Design a Moon Base Habitat (Hab) NASA is to build a moon base to be visited regularly during the moon’s daylight period. The construction will start late in 2018. The moon base will consist of an accommodation Hab, a science laboratory Hab and large airlock for rovers and moonwalkers. The accommodation Hab will be the first to land on the Moon. You have been given the contract to make the accommodation Hab! Contract: Provide an accommodation Hab that is to be located on the moon and lived in during the moon’s daylight period of 14 days. It must be at Cape Canaveral on 1 st July 2018 for launching to the moon. The Hab is to have: - Provision for 6 people to sleep, exercise and relax; - The Hab must have capacity to be independent from the moon base; - A 500 kg, 5 m³ emergency airlock; - A walk through docking port in one location to connect to other Habs; - Supplies and space for the 6 people suitable for a total of 30 days; - Solar cell power generator that will be erected on the moon by the first visiting astronauts - The Hab must fit in the ‘heavy lift rocket’ payload space that is a diameter of 7 metres and 20 metres long; - 50 Year life with capacity to be modified.
Concept Design Process – STEP 1 Define the project aims, scope of work and technical specification Concept Design Process Mission statement or general aim, NASA is to build a moon base to be visited regularly during the moon’s Scope of work and daylight period. The construction will start late in 2018. technical specifications The moon base will consist of an accommodation Hab, a science laboratory Hab and large airlock for rovers and moonwalkers. List Assumptions Scope of work Develop Concept Provide an accommodation Hab that is to be located on the moon and lived in during the moon’s daylight period of 14 days. It must be at Cape Canaveral on 1 st July 2018 for launching to the moon. Technical specification: The Hab is to have: - Provision for 6 people to sleep, exercise and relax; - A 500 kg, 5 m³ emergency airlock; Assess risks & - A walk through docking port in one location to connect Check that Aims or general specification are satisfied to other modules; - Supplies and space for the 6 people for a total of 30 days; - Solar cell power generator that will be erected on the moon by the first visiting astronauts Detailed Concept - The module must fit in the ‘heavy lift rocket’ payload Detailed Design space that is a diameter of 7 metres and 20 metres long; - 50 year life with capacity to be modified.
Concept Design Process – STEP 2 List Assumptions Concept Design Process -The moon environment is: -A vacuum and Habs must be pressurized; Mission statement or general aim, Scope of work and technical specifications -An average temperaturer of 253ºK during daytime. Habs must have insulation and radiators to dump wast heat. List Assumptions Develop Concept -The module must be re-supplied with 14 days supplies when the crew arrive for their 14 day stay. -The emergency airlock can be used for other things as it will be rarely used. -The module must have a shower, toilet and 6 bunks/rooms; Assess risks & Check that Aims or general specification are satisfied -The solar cells can be cleaned by the astronauts in moonwalks and are operational 90% of the time. Detailed Concept Detailed Design
Concept Design Process – STEP 3 -1 Develop Concept : Estimate the volume and define a geometry/shape - 1 Consider the graph above (NASA-STD-3000) It shows the ‘free’ space person considered as ‘accepted’ over given time periods. If a person has less than the accepted ‘free’ space then it is considered as ‘intolerable’ for the person. Remember the graph is for spacecraft in orbit with crew in 0 G conditions where ‘free’ space is more easily usable. Our Hab is on the moon. We are to design ‘free’ space for 30 days or 1 month. This translates to a minimum of 4 m³ but better with 10 m³ free space. We will use 10 m³ free space as our minimum bench mark. This is not much – a cube 2. 15 metres per side!
Concept Design Process – STEP 3 -2 Develop Concept : Estimate the volume and define a geometry/shape - 2 Now consider the graph above (NASA, 1995) It shows the history of total space person over given time periods for various spacecraft. Thisincludes space for ‘free space’ and ‘space for equipment and supplies’ for time durations. Again remember the graph is for spacecraft in orbit with crew in 0 G conditions where space is more easily usable. Our Hab is on the moon. We are to design space 30 days or 1 month. This translates to a 20 m³ space person. This is still not much space!
Concept Design Process – STEP 3 -3 Develop Concept : Estimate the volume and define a geometry/shape - 3 Volume and find a ‘first pass’ mass Estimate Volume: The previous slide suggested we use a total space of 20 m³ person. Thus for 6 people, Volume = 6 people x 20 m³/person = 120 m³ ‘First pass’ Mass Estimate: Design history of manned spacecraft show that the mass of the spacecraft habitation space is a function of Volume, Number of crew and Endurance time. We use the algorithm Mass = 592 x ( Volume (m) x number of crew x Endurance (days))^0. 342 = 592 x (120 m³ x 6 crew x 14 days)^0. 342 = 13, 850 kg Geometry and shapes Note: The shapes must have rounded corners to minimize the bending stresses when pressurized. Sphere Most mass efficient shape. Has the least surface area for volume enclosed The walls can be half as thick as a cylinder to carry the same load. Volume = 4/3 (PI) R³ Surface area = 4 (PI) R² Cylinder Is easy to move around and bury under regolith. Nice shape to fit together. Tuna Can More mass efficient shape Good as a stable landing platform Volume = (PI) R²/2 x L Surface area = 2 x (PI) R²/2 (ends) + (PI) x D x L
Concept Design Process – STEP 4 Develop Concept Geometry and Structure We choose a cylinder as our geometry as it is more useful to for connecting to other HABs. - Adopt 4. 2 m diameter as it can be cheaply manufactured and transported on Earth. - Adopt 9. 5 m in length as this provides a volume of 120 m³. Item Mass/m² Thickness Description Outer shell 22 kg/m² 80 mm Double walled aluminum shell including insulation Internal walls 8 kg/m² 50 mm Double walled carbon composite incl insulation Internal floors 15 kg/m 150 mm Double walled carbon composite incl insulation Item Area Mass. Volume Monocoque structure Outer shell 140 4, 200 kg 120 m³ Isogrid strucure Walls 70 560 kg 3. 5 m³ Graphite/epoxy composites Floors 33 500 kg 4 m³ TOTAL 5260 kg Note: For spherical structures use outer shell 17 kg/m
Concept Design Process – STEP 5 Supply and recycling CO 2 Removal Li. HO 4 Bed Molecular Oxygen sieve (4 -BMS) Storage Mass 7 kg/4 p/day 30 kg/p 1 kg/p/d Volume 0. 005 m³/Cartridge 0. 15 m³/p Power 12 W 0. 3 k. W/p - 0. 07 m³/p 4 -BMS: 4 beds of synthetic zeolites or aluminum-silicate metal, two beds for CO 2 obsorption and another two for water vapor material. The beds are heated to expel the CO 2 overboard and water vapor collected. The Russian Mir space station used KCLO 4 Potassium Perchlorate, where 1 kg KCLO 4 provides 0. 46 kg/p/d. A person requires nominally: -30 kg supplies/person/day -This consists of: -27 kg water per day for drinking and washing. -2 kg, food including 2/3 mass water per day. -1 kg Oxygen per day We can recycle 24 kg water via the air conditioning, filtering washwater and distilling urine As such each day a person wastes nominally 6 kg in the form of CO 2 some urine, faces and Brine. The supply mass budget per day person = 6 kg/day/person
Concept Design Process – STEP 6 -1 Develop Concept : Equipment and supplies Number of Crew 6 Mass unit Number of days 30 allowance Consumables (/person, /day or /person per day) Food (including 2/3 water) 2. 30 kg/p/d Water O 2 Gas leakage - water kg/day Gas leakage - O 2 kg/day Gas leakage - N 2 kg/day kitchen cleaning supplies cooking utensiles Mass kg Volumesunit subtotal 414 Volume m^3 subtotal 0. 008 m 3/p/d 1. 44 513. 9 0. 002855 m 3/p/d 151. 2 0. 0007 m 3/p/d 1. 5 0. 00005 m 3/d 36 0. 001 m 3/d 0. 00462 112. 5 96 m 3/d 7. 5 0. 0018 m 3/d 30 0. 014 m 3/p 0. 51 0. 13 0. 00 0. 03 0. 14 0. 054 0. 084 2. 86 0. 84 0. 05 1. 2 kg/p/d 3. 75 0. 25 5 kg/d 0. 23 kg/p/d 41. 4 0. 0008 m 3/p/d 0. 144 0. 05 0. 075 1. 8 99 50 0. 1 0. 05 kg/p/d 9 13. 5 10. 8 594 300 18 9 0. 0013 0. 0015 0. 005 0. 336 0. 75 0. 002 0. 001 0. 234 0. 27 0. 03 2. 016 4. 5 0. 36 0. 18 Contingency fecal & urine collection bags WCS suppies (toilet paper, cleaning, filters etc) Hygiene supplies Personal hygiene kit Clothing Personal stowage/closet space Disposable wipes Trash bags Operational Supplies (diskettees, ziplocks, velcro, tape) Sleep provisions Subtotals TOTAL : 25% on mass+50% volume 20 9 kg/d kg/p kg/p/d kg/p 120 54 2436. 3 3045. 4 m 3/p/d m 3/p/d 0. 002 m 3/p 0. 1 m 3/p 0. 012 0. 6 10. 73 16. 10
Concept Design Process – STEP 6 -2 Develop Concept : Equipment and supplies Number of Crew Number of days Fixed Resources Freezers Conventional oven Microwave oven 2 ea Sink, spigot for food hydration and Drinking water Dishwasher Waste collection system 2 off Shower Handwash/mouthwash faucet Washing machine Clothes dryer Restraints and mobility aids Vacuum (prine + 2 spares) Trash compactor/trash lock Hand tools and accessories Spare parts/equipment & consumables Test equipment (oscilloscopes, gauges etc) Fixtures, large machine tools, Goveboxes, etc Equipment (still & vidio cameras, Lenses, etc) Film (assume digital) Exercise equipment Medical/surgical/dental suite Medical/surgical/dental consumables Fixed resources Subtotals Total incl 25% on mass+50% volume 4 Mass 30 allowance 0 50 70 unit kg kg Mass kg Volumes unit subtotal 0 0 m 3 50 0. 25 m 3 70 0. 3 m 3 Volume m^3 subtotal 0 0. 25 0. 3 15 40 90 75 8 100 60 100 13 150 300 0 kg kg kg 15 40 90 75 8 400 60 100 13 150 300 0 0. 0135 0. 56 4. 36 1. 41 0. 01 0. 75 0. 54 0. 07 0. 3 1 0 m 3 m 3 m 3 0. 0135 0. 56 4. 36 1. 41 0. 01 0. 75 0. 54 0. 07 0. 3 1 0 100 kg 100 0. 3 m 3 0. 3 250 kg 250 0 m 3 0 120 0 145 200 50 kg 120 0 145 200 50 2236 0. 5 0. 19 0. 8 0. 25 m 3 0. 5 0. 19 0. 8 0. 25 12. 35 kg kg kg 2795 m 3 m 3 18. 53 Total Mass and Volume, Consumables + Fixed = 5850 kg & 34. 5 m 3
The Solar Generator Design Assumptions Concept Design Process – STEP 7: Power cyclopedia of Space, Cambridge University Press, Cambridge, p 137 th – The Integration of Existing Technologies for Efficient, Affordable Space Flight Agriculture. ” 29 International Conference on Environmental Systems Denver, Color We are using a solar cells power generator The Moon has continuous sunlight for 14 days The solar energy flux in Earth orbit/Moon = 1370 k. W/m² We can assume solar cell efficiency for long term life = 15% but can be higher Also adopt and mass per Watt = 55 Watts/kg Suggest to allow an additional 50% to allow for the twilight period. For the concept allow 3 k. W person. This covers the environmental system radiators, stoves fridges etc. As such we require 27 k. W mass = 490 Kg solar panels
Concept Design Process – STEP 7: Concept Questions: Are the rooms placed well for: -dealing with sound? -dealing with dust if the airlock is used? -connecting to other moon base ‘Habs? -Is the airlock practical in terms of entrance and exit?
Concept Design Process – STEP 7: Concept We are using a solar cells power generator Item Mass Volume Structural Mass 4, 200 kg 120 m³ Fixed resources 2, 800 kg 18. 5 m³ Expendable Supplies 3, 050 kg 16. 4 m³ Airlock 500 kg 5 m³ Solar Generator Power 460 kg Margin (25%) TOTAL Free Volume 2, 750 kg 13, 760 kg. Our original guess was 13, 800 kg 82 m³ This is 13. 6 m³ person and is > than our minimum 10 m³/person
Concept Design Process – STEP 8: Risk Assessment Risk Likelihood Consequence Rank Solution Return ship may fail and Astronauts may stay longer than 14 days E 5 M No solution Return ship cannot fail Environmental system fails A 5 A Provide back up environmental system Astronauts Become ill D 3 M Medical supplies and automated return ship Solar Storm E 4 M Provide moon base with radiation shelter. Structure punctured by meteorite E 5 M Retreat to airlock & provide space suits in airlock. Cosmic Rays A 1 M Cover base with regolith in long term For the exercise you need to consider the risks and select a matching ‘Likelihood’, ‘Consequence’ and ‘Rank’ An acceptable rank is ‘L’ or low to ‘M’ or medium. If it is not ‘L’ or ‘M’ then we need a ‘ design’ or ‘procedure’ solution in place to make it L or M You need to consider the solution or procedure and write it in the column above
Exercise: : Undertake a Risk Assessment on NASA’s Proto- type Manned Luna Rover: Forward your answers to NASA! Note the ‘Port Suits’. Astronauts climb into them through a door in the rear of the rover compartment. Suggested Issues to Consider: -How reliable do you think it would be in off road terrain compared to a ‘Land Rover’ vehicle? - What happens if it collides with a boulder or drives into a ditch? - Do you think it will be stable with the moons low gravity? - Do you think it is safe to climb on and off the rover in the suits? - How much maintenance do you think would the rover need compared to a ‘Land Rover’ vehicle?
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