09-17-2019, 10:17 PM | #51 |
Join Date: Feb 2016
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Re: Realistic STL Interstellar Missions
50% is not that much in 50 years. Even if we continued with that date of increase, it would take six or seven centuries to get to 5% c. For reasons specified above, we are unlikely to get above 5% c unless one of the FTL schemes end up working.
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09-18-2019, 04:41 AM | #52 |
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Join Date: Oct 2007
Location: Indianapolis, IN
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Re: Realistic STL Interstellar Missions
How vast? More than what it takes to build a city?
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Joseph Paul |
09-18-2019, 05:34 AM | #53 |
Join Date: Feb 2016
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Re: Realistic STL Interstellar Missions
Well, the cost is around $10 million per person at TL10 assuming mature technology. If you are producing a one-of-a-kind spacecraft, you are probably increasing the cost by 100x, as you have to include research and development, infrastructure costs, training costs, etc. If it is the only spacecraft produced of that type, the cost would probably end up being $1 billion per person, meaning $10 trillion for a mission of 10,000 people. By comparison, the average city would cost around $500,000 per person in total infrastructure costs (including housing), so $10 trillion would build a city of 20 million people.
Realistically, a society would be unlikely to invest more than 5% of GDP per year on interstellar missions, with 1% of GDP per year being more likely after the first decade. A mature and developed TL10 society with 10 billion people has a GDP of ~$670 trillion per year, so 5% is ~$33.5 trillion per year and 1% is ~$6.7 trillion per year. A one-of-a-kind mission could be launched, though it would be difficult to justify, so a continuous production would make more sense, meaning that the society would likely send out 670,000 people per year, as well as employing millions of people directly and supporting millions of people indirectly. If we assume construction in the Neptunian Trojans, it would probably be the reason for the colonization of the outer edge of the Sol System. With ~6.7 million people working directly on it, another ~26.8 million people would provide support services for those people. When you include dependents, spouses, retirees, etc., the total population impacted by the construction of the missions would probably be around ~53.6 million, meaning >0.5% of the entire system would depend on the missions. |
09-18-2019, 10:52 PM | #54 | |
Join Date: Feb 2007
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Re: Realistic STL Interstellar Missions
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The scale of resources necessary to build an STL starship are relative to the overall wealth and size of the society. For us today, yeah, it would be a global project. In fact, it would be super-global, beyond us for all practical purposes. But a Solar System wide society, multiple orders of magnitude wealthier than our own, would be a different critter. Likewise, exactly how big the cost (broadly defined) of such a project would be would depend on what tech was required to instantiate it. 'Realistic cost' is relative.
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09-18-2019, 10:54 PM | #55 |
Join Date: Feb 2007
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Re: Realistic STL Interstellar Missions
Compared to the previous time period, it's peanuts. The time period from 1850 to 1950 (roughly) saw orders of magnitude increases in speed and performance. People who travelled west in covered wagons lived to see astronauts travelling at multiple miles per second.
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09-18-2019, 11:16 PM | #56 |
Join Date: Feb 2005
Location: Berkeley, CA
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Re: Realistic STL Interstellar Missions
Interstellar travel at .05c requires a minimum energy budget of 1.125e+14J/kg, and no rocket will achieve even half that, call the actual energy budget 3e+14J/kg. Low end of current electricity prices is about $4e-8/J, but less useful energy might go less, call it $1e-8/J, putting a low end price of $3M/kg or $3B/ton. It seems unlikely that we can manage less than a ton per person, so based on TL 10 wealth of $75k/person, we only need 40,000x starting wealth per person you send.
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09-18-2019, 11:29 PM | #57 | |
Join Date: Jul 2007
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Re: Realistic STL Interstellar Missions
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For extra complication, if the probe crew waves the main ship off, they are doomed. Might bias their results.
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09-19-2019, 01:19 AM | #58 |
Join Date: Dec 2007
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Re: Realistic STL Interstellar Missions
No. It wouldn't. For us today it would just be an impossible project. We aren't rich enough to do it at all.
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09-19-2019, 08:09 AM | #59 | |
Join Date: Feb 2016
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Re: Realistic STL Interstellar Missions
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Since 96% of the energy from the 0.05c spacecraft comes from a ramscoop, you can further discount the effective cost of energy by 96%, since energy is the square of velocity. That would reduce the cost of energy to effectively 0.16% as much as at TL9. In addition, you can use processes that would be wasteful for electricity generation but perfectly fine for propulsion generation. Since you do not have the infrastructure for generating and transmitting electricity, and since you to not need to protect 100% of the environment from radiation, you can reduce the associated costs of energy by effectively 96%. That would reduce the cost of energy to effectively 0.0064% as much as electricity at TL9. The end result would be the 3.125 PW-h of kinetic energy per person would be worth as much as 200 GW-h at TL9. If we assume a wholesale price of $30,000/GW-h, that ends up being $6 million per person, less than the $10 million per person budget. |
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09-19-2019, 08:16 AM | #60 |
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Join Date: Mar 2012
Location: far from the ocean
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Re: Realistic STL Interstellar Missions
correct me if I'm wrong, but I thought ramscoops ended up being inefficient for propulsion -- though they still work for slowing down, which might give you a sizable chunk of savings... but its going to end up being under half.
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