Section 5.1: Conceptual Design for Human Expansion< Space Transport and Engineering Methods
Conceptual Design StageEdit
The first stage in the life cycle of a well-designed program is Conceptual Design. The goals of this stage are to identify the needs to be satisfied, the selection criteria to be used, an initial concept for the major system elements, and how they will be built, operated, maintained, and disposed. The alternatives to building a new system are to do nothing or to continue with existing projects and programs. We therefore assess our system concept against those alternatives and decide whether to go further or to stop. We do this using the selection criteria previously chosen.
For our example program we give the motivation in terms of general goals first, with potential reasons to change from current space programs. Not every goal will have the same importance to every person or organization. As long as a sufficient number of goals apply to them, they would have a reason to support the project. Following the goals we describe our design approach in general terms. The rest of Part 4 will go into more detail of the design process and results.
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Conceptual Design is the first stage in the life cycle of a program or system. We determine needs and goals to be satisfied, what criteria to use in selecting among designs, and a design concept for the major parts of the program, including how they will be built, operated, maintained, and disposed at end of life. We compare our new program to existing programs using the same selection criteria. If the new program is "better" by these measures, we recommend going forward to the next design stage. If it is not better, then we stop and wait for circumstances or technology to change, or try to devise alternate concepts. The full details of our reasoning, calculations, and decisions are too long to include in our discussion here. We will summarize them here, and refer readers to the full Human Expansion Design Study for the details.
The general process flow in Conceptual Design starts with general description and goals, which are noted in the next section. Following that we perform an analysis step to develop these goals into more detailed and quantitative statements. At present this has been done for the program requirements and evaluation criteria. The functional analysis to define more detailed program elements has been started, and later parts of the Conceptual Design process are incomplete. Candidate designs to fulfill the program elements are collated in the remainder of Part 4. They should be considered as pieces which might fit into the overall program, but have not yet been linked, or completed individually.
Program and CustomerEdit
We begin by identifying who is the Customer for our program and what their needs are. Any proposed program involving many people needs sufficient motivation for why to do it instead of the alternatives of doing nothing, or continuing with what is being done now. If you are building a system entirely by yourself, then "I want to do it" is enough, but for larger systems you typically have to convince end customers and developers of its value. The motivations can be couched in terms of general goals, or financial benefits, or simple efficiency, or even "I have a gun, do this or else" for totalitarian societies, but they must be there in some form. When the end customer is unaware of a program's value, they need to be informed about it, preferably not at the point of a gun. Thus how to format and deliver the results needs to be considered along with the technical results.
Customer vs Designer - Customers can be internal or external. The former case is when the same organization is both the user and designer of a system. The latter case is the more common one for large systems, where design specialists develop systems for another entity than themselves. For our future program then we must ask who is setting the program goals and is thus the customer, and who is doing the design work? For now both are actually the editors of this page, but we will assume a non-profit foundation will continue the initial design work using open-source methods. As a foundation they would set goals for the benefit of civilization as a whole, and publish the results of their work publicly. Assuming good enough results are reached, then fund raising for later research, start-up of commercial entities, or promotion of government funding would be used for later stages. The ultimate customer is therefore civilization as a whole, and the designers are part of an open-source non-profit foundation. At present this is the Wikimedia Foundation editors of this open source book, but that may transition to a specialized organization later.
Customer Acceptance - Some people or groups will be negatively affected by a new project, in particular those associated with older existing projects. Other people simply do not like change, or are averse to the risks of new or untried methods. Yet others have a preference or aversion to particular designs separate from their technical merits. Finally, some methods are simply new and unfamiliar and not considered for that reason. A system designer has to understand these human elements and respond to them, and not assume that the best technical answer will be accepted just because it is the best technical answer.
Program Constraints - Beyond technical design, there are also outside factors, such as available funding or restrictions on technology transfer, which affect the course of a program. These outside factors need to considered in addition to the technical and human ones.
Human civilization desires, as the sum of individual desires, to survive over the long term, with lower risks individually, and to flourish materially and socially. Therefore we state the following individual program goals to satisfy these desires. We group them into those that benefit civilization in general, and then those that apply to individuals or groups of smaller size. By the end of the conceptual design stage, these will be refined to final goals and specific numerical objectives.
Our earthly civilization should be motivated to visit, develop, and expand into space for a number of reasons. These reasons can stated in terms of individual goals. A future program or programs ideally can satisfy more than one of these goals at once:
- Improve Life on Earth - Attempting new and challenging things tends to discover new knowledge and develop new technology. Such developments can first be applied on Earth to improve our life here, particularly in the areas of energy, resources, automated production, and closed ecologies. With experience gained on Earth we can then use these developments in space.
- Understand the Earth Better - We learn more about how the Earth works by looking at it's current environment in space, because the Earth is not isolated in the Universe. We also learn from looking at other examples of planets and environments and how they evolve. Except for the one part per billion of human kind currently in orbit, all of us live on the Earth, it's a good idea to understand it better.
- Reduce Hazards from Space - There are hazards in space such as solar flares and asteroids which can affect us here on the ground. In order to prepare for or prevent these hazards, we first have to know their magnitude and characteristics, followed by developing methods to prevent or deal with the hazards.
- Increase Biosphere Security - There is only one biosphere right now that we all depend on, and it is prone to natural and man-made variations (ice ages, CO2 changes, volcanoes). Even the International Space Station relies on food and other supplies which come from Earth. Observing from space helps us understand how the Earth varies better. In the long terms we should also set up backup biospheres for survival reasons in case something catastrophic happens to the only one we have.
- Expand Material and Energy Resources - Civilizations require materials and energy to function, and there are vast material and energy resources beyond the Earth. We could move heavy industry and population off the Earth to reduce our impact to the planet.
- Long Term Survival - In the long term the Earth is doomed as the Sun continues to get hotter over its life, and eventually turn into a red giant and swallow it. Long before then, it will become a poor place for life because the Sun increases it's luminosity over time, eventually overheating the planet. Our choices are planetary scale engineering to deal with the eventual heat, or moving elsewhere. Either way involves space in some way.
In addition to goals which apply to civilization as a whole, there are motivations which apply to particular individuals or groups. These more localized goals can overlap with the more general ones listed above:
- Increased Choice and Freedom - Freedom of choice is restricted in many ways by an occupied and relatively crowded Earth. You cannot just set out and start your own community, with your own rules for living, because all the land area of the Earth is already claimed by some government and functions under their rules. Dangerous or dirty experiments, whatever their scientific value, have to be restricted, and some experiments, like terraforming, simply cannot be done on the Earth. At least to start with, space is unoccupied and will not be crowded for a long time, so earthly restrictions are lifted. Space will impose it's own restrictions due to environment and resources, but they will at least be different restrictions. This widens the total range of available choices.
- Increased Opportunity - Unlike Earth, where almost everything is already claimed by someone, there are many unclaimed resources in space. Lack of acquisition cost from a previous owner means a wider opportunity for gaining wealth, but of course not a certainty of it. The ratio of available space resources per person will start very high, partly because there will not be very many people at first, but also because the absolute amount of matter and energy available in space exceeds that on Earth by a wide margin. This high relative availability of resources creates new opportunities for those who wish to exercise them.
In theory the above goals could be met by existing space programs. So in addition to stating our goals and the reasons behind them, we have to demonstrate why a new system is better than just continuing what is being done now. This is the intended result at the end of the Conceptual Design stage. Where we are now, which is the start of that stage, we can only list the potential benefits identified so far. Additional ones may be identified later, and some of those listed below may not prove favorable once the concepts are developed further.
New Systems Can Lower Cost Dramatically:Edit
If we stay with existing programs, we will get existing planned costs. The planned costs include future projected cost reductions of systems already in development. A new system has the potential to reach even lower cost. The following argument establishes the potential gain is very large. Therefore new systems should be examined to find out if they can actually reach some part of that potential. This can only be done with a sufficiently detailed design that considers all of the cost elements.
- Existing program costs are much higher than what is possible:
With all the many billions of dollars spent by governments and private industry on space projects, we have only managed to get about 1000 useful satellites and a half dozen people working in space. This is because past programs had launch cost measured in their weight in precious metals. For example, the Atlas V is listed as delivering 20 tons to Earth orbit for US $110 million. The cost of $5,500/kg comes to $171 per troy ounce, vs a mid-2012 price of $1600 for gold. The new Falcon 9 commercial rocket reduces that somewhat to 13.15 tons for US $54 million, or $128/oz ($4,100/kg), and the upcoming Falcon Heavy is quoted by the manufacturer at 53 tons for US $83 million, or $49 per ounce ($1,566/kg). This compares to an average of $30/oz for silver in the first half of 2012.
The raw energy cost to get to Earth orbit, which is about 33 MJ or 9.25 kWh/kg, works out to about $1/kg at typical retail cost for electricity. This is slightly higher than the price of Carbon Steel as of 2012, or roughly the retail price of potatoes per kg. Efficient shipping to orbit should in theory run several times raw energy cost, or roughly the cost of cheese or priority mail packages. The ratio of upcoming launch costs and theoretical cost is still about 400:1, indicating there is much room for improvement. As long as launch costs are measured in their weight in precious metals, rather than cheese, it should be evident not much will be done in space. One billionth of the world's population being in orbit counts as "not much".
- High costs are driven by launch technology:
Conventional rockets, which carry all their own fuel, cannot get really cheap and efficient because the energy to reach Earth orbit is about twice the energy in chemical rocket fuel. Therefore you have to burn a lot of fuel to get a smaller amount of fuel halfway to orbit, which in turn you burn to put an even smaller amount of cargo into orbit. So after subtracting fuel, fuel tanks, and rocket engines, about 3% of what sits on the launch pad is the delivered cargo. Even worse is that the hardware is expensive aerospace-grade hardware and is often used only once and tossed away. By comparison, airplanes use the same kind of aerospace grade hardware, and so cost about the same $/kg to build. But being more efficient (they get oxygen from the air, rather than from a tank) they carry a higher percentage of cargo, and the airplane is used many thousands of times, thus making it dramatically cheaper per trip.
- Launch cost and lack of resource use drives high total cost:
The high cost of everything else in space is partly because of the high cost of getting to orbit, and partly because everything you need in space is currently brought from the ground. Since shipping is so high, designers spend a lot of effort making the cargo lighter by spending more time refining the details, and by using more exotic, but stronger, materials. That extra effort makes the cargo more expensive also. Since you optimally spend money making it lighter to the point where each kg saved costs the same as launch cost, cargo cost tends to be proportional to launch cost. If you lower the cost of launch, then it will also tend to make whatever you are carrying cheaper (and heavier).
The other important cost factor is the practice of bringing everything from Earth, and thus paying shipping on all of it. If you could get some of needed supplies from space and recycle more, the amount that has to be shipped to do a project or mission could be cut drastically. There are plenty of energy and material resources in space if we learn to use them, and for many of them the shipping energy is dramatically lower than from Earth. The combination of launch cost, cargo cost, and bringing it all from Earth results in very high total project cost.
- A potential improvement of 20,000 times is possible:
Even an ideally efficient launch system will still have costs for development and operation, therefore will not reach raw energy cost. We will assume that 4 times that cost, or $4/kg is a practical lower limit. This is 400 times lower than the quoted price of the Falcon Heavy. Past studies have estimated that 98% of space systems could be made of local resources, and the remaining 2% would be rare or difficult to make, and thus more economical to transport from Earth. This gives a 50 times reduction in the amount of cargo that needs delivery. Combining the cost and traffic improvements gives a 20,000 times total potential improvement. That level of improvement will not be reached soon, and perhaps never, but the potential is so large it definitely justifies some engineering effort. How much is worth spending to get an improvement can be judged by the US $290 billion/year currently spent worldwide on space-related projects.
Developing New Systems Has Side Benefits:Edit
- Technology Spin-off:
Technology developed for one purpose or project often finds uses in other areas, a process called Spin-off, or technology transfer. One example is biochips for medical testing which use the technology developed for electronic microcircuits. Although there are many other such examples, they are unpredictable in individual cases. Space projects are not unique in generating spin-off technology, but they typically have a large amount of research and development effort, and thus more than average opportunity for it. There have been attempts to quantify spinoff benefits specifically from NASA programs. While we cannot put an exact value on spin-off technology, we can make an allowance for some amount as part of the reason to pursue new systems over current systems.
When space systems are intentionally developed with an eye to Earth applications it becomes less of a spin-off and more a matter of design intent. This is referred to as dual use or multi-use technology. For example, solar cells were first used on a significant scale to power satellites, but now there major application is on Earth.
- Expanded Markets:
Significantly lowered cost to do space projects can expand existing markets for things like communications satellites, or open new markets such as asteroid mining for rare metals. Increased supply and lower cost for these metals can prompt new uses for them which are not economic at present. Therefore in addition to the direct benefits of lower cost, some estimate should be made for the secondary effect of expanded or new markets in the total value of a new system.
- Optimism for the Future:
Fear of loss is twice as strong an emotion as opportunity for gain. If the Earth is seen as a finite, closed, zero-sum world then fear of the future can dominate. In that view people might take less risk and try to hold on to what they have. This perception is not reality - from an engineering point of view the Earth is open in energy and mass flows. However, perception can affect actions even if incorrect. An understandable path to opening the resources of the Solar System can change a pessimistic world-view to one with hope. There are other ways to change negative perceptions of the future, such as the development of affordable, clean energy sources. Opening space, though, directly refutes the idea of a closed Earth. A more optimistic world might be less fearful of new technology and more willing to invest in long term projects.