Interstellar Trade: Value, Resources & Unobtanium

[stefan r]

The OP said the energy of Tzar Bomba, not that he was literally using nuclear weapons as a propulsion method.

Could we use textbook or a bag of apples? 2½ kilograms should be enough if E = mc².

If we assume a fusion reactor powering a steam punk mechanical FTL device is the 2 x 10¹⁷J the energy released by deuterium during fusion or the energy needed to crank the pistons? Does the reactor just generate electricity which then gets consumed? Could we slowly accumulate 2 x 10¹⁷ joules and then make a 3 month jump or does the reactor have to run steady at over 33 gigawatt? If this is a carnot cycle how do you unload 3 times the power of the space shuttle? In noisy rysling's version we only have 10⁶ kilo of ship, 33 kilowatt per kilogram. Could get toasty.

I like my version better. light off the reaction then escape through hyperspace were the explosion cannot keep up.

 

[snorkack]

For example, a Liberty ship has a payload of 10 200 t. Needs a crew of 40...60. Normal endurance of about 1800 hours, meaning 75 days of cruise.

So, suppose you do build a spaceship. Try to consider the breakdown of major cost items over one mission:

1. Fuel expended for ship and payload
2. Salaries, food and air of the crew
3. Wear and tear related depreciation of the ship
4. Financial depreciation of the initial investment of the ship

What´s the total, and what´s the breakdown between those 4 groups?

 

[GTOM]

Could we use textbook or a bag of apples? 2½ kilograms should be enough if E = mc².

If we assume a fusion reactor powering a steam punk mechanical FTL device is the 2 x 10¹⁷J the energy released by deuterium during fusion or the energy needed to crank the pistons? Does the reactor just generate electricity which then gets consumed? Could we slowly accumulate 2 x 10¹⁷ joules and then make a 3 month jump or does the reactor have to run steady at over 33 gigawatt? If this is a carnot cycle how do you unload 3 times the power of the space shuttle? In noisy rysling's version we only have 10⁶ kilo of ship, 33 kilowatt per kilogram. Could get toasty.

I like my version better. light off the reaction then escape through hyperspace were the explosion cannot keep up.

I think only antimatter or exotic particles can have enough energy density, they don't literally blow up a real nuclear bomb. But yeah they jump very far from any gravity well.

Energy dense areas. Theoretically Sun could also give very much energy with a Dyson sphere, although i find the ideas of theese megastructures pretty irreal, at least with my constraints, interstellar trade is magnitudes easier than build such a thing.

 

[Noisy Rhysling]

The OP said the energy of Tzar Bomba, not that he was literally using nuclear weapons as a propulsion method.

Namu amida butsu! I thought I was going to be ringside at a cosmic calamity.

 

[Noisy Rhysling]

For example, a Liberty ship has a payload of 10 200 t. Needs a crew of 40...60. Normal endurance of about 1800 hours, meaning 75 days of cruise.

So, suppose you do build a spaceship. Try to consider the breakdown of major cost items over one mission:

1. Fuel expended for ship and payload
2. Salaries, food and air of the crew
3. Wear and tear related depreciation of the ship
4. Financial depreciation of the initial investment of the ship

What´s the total, and what´s the breakdown between those 4 groups?

If you use robot haulers the second item is "zero".

 

[stefan r]

If you use robot haulers the second item is "zero".

The robots consume energy and need replacement parts and servicing. You could lump #2 in with #s 1 and 3 as fuel, depreciation, and wear but you could say that for a human crew too. "Food" is just a special type of fuel used for autonomous meat robots.

The FTL drive itself is pure fiction. It might as well need food.

I think only antimatter or exotic particles can have enough energy density, they don't literally blow up a real nuclear bomb. But yeah they jump very far from any gravity well.

Energy dense areas. Theoretically Sun could also give very much energy with a Dyson sphere, although i find the ideas of theese megastructures pretty irreal, at least with my constraints, interstellar trade is magnitudes easier than build such a thing.

All components of a Dyson swarm have already been demonstrated. The technology was available in 20th century. The DOE and NASA wrote a report on it in 1978. On page i:

The concept presented is considered to be in the proper "direction," but is not optimum at this time. The system definition studies, however, indicated technical feasibility of the reference concept...

Self supported living in space has not been demonstrated. If you have technology sufficiently advanced to allow space colonies then the technology for a Dyson swarm is primitive. The limitations I am aware of are time, Kessler syndrome, and the mass of "expendable" planets. Dyson swarm would make a good thread.

If you have FTL you can choose any position. Around AGB stars and near the barycenter of binary you can levitate foil. Easy to keep orbital velocities well below velocities that weak tethers can handle. This gets overlooked in discussions about SETI because there is not a plausible explanation for the evolution of life suspended at the barycenter of two stars. AGB stars have short duration and are not stable enough for evolutionary timelines. A space based civilization that can choose to jump around anywhere in the galaxy will have an easy time building megastructures. Using ±5° area you can capture 2.4% of luminosity. For sun like stars that is around 10²⁶ watts. If you can make one millionth of the energy available for interstellar trade you can move 500 mother ships per second. An AGB star could handle millions of motherships per second.

 

[Noisy Rhysling]

Okay, that stuff about fuel being food is just silly.

 

[GTOM]

The robots consume energy and need replacement parts and servicing. You could lump #2 in with #s 1 and 3 as fuel, depreciation, and wear but you could say that for a human crew too. "Food" is just a special type of fuel used for autonomous meat robots.

The FTL drive itself is pure fiction. It might as well need food.
All components of a Dyson swarm have already been demonstrated. The technology was available in 20th century. The DOE and NASA wrote a report on it in 1978. On page i:Self supported living in space has not been demonstrated. If you have technology sufficiently advanced to allow space colonies then the technology for a Dyson swarm is primitive. The limitations I am aware of are time, Kessler syndrome, and the mass of "expendable" planets. Dyson swarm would make a good thread.

If you have FTL you can choose any position. Around AGB stars and near the barycenter of binary you can levitate foil. Easy to keep orbital velocities well below velocities that weak tethers can handle. This gets overlooked in discussions about SETI because there is not a plausible explanation for the evolution of life suspended at the barycenter of two stars. AGB stars have short duration and are not stable enough for evolutionary timelines. A space based civilization that can choose to jump around anywhere in the galaxy will have an easy time building megastructures. Using ±5° area you can capture 2.4% of luminosity. For sun like stars that is around 10²⁶ watts. If you can make one millionth of the energy available for interstellar trade you can move 500 mother ships per second. An AGB star could handle millions of motherships per second.

Dyson swarm that capture a few percent of light is ok, i just think a full sphere requires too much material.

Well even on rogue planets and gas clouds they can still fusion hydrogen, so i don't think they would require imported energy.
But if we look at really high energy applications like produce antimatter, and material/technology needs extreme energy density, it can be more practical to move mined stuff around AGB (What that exactly means?) stars, where they process it, then send it to pleasant Solar system like places.
And the pleasant places can send luxury stuff (spice, courtesans ? ) to mining outposts, where there arent enough capacity to produce large quantities.

 

[stefan r]

Dyson swarm that capture a few percent of light is ok, i just think a full sphere requires too much material.

Well even on rogue planets and gas clouds they can still fusion hydrogen, so i don't think they would require imported energy.
But if we look at really high energy applications like produce antimatter, and material/technology needs extreme energy density, it can be more practical to move...

The turn around on a solar collector would be a major factor. Not far from 13.4 kg per m² for current market panels and solar irradiance at Earth is about 1340 W/m² so orbiting near Earth silicon panels can get 100 W/kg. Film panels could do much better and you can use mirrors. Some current satellites are getting 300 W/kg. We get 10⁶ kg per trip in this thread and the trip is 2 x 10¹⁷ J so the energy is recovered with 2 x 10¹¹ J/kg so 6.6 x 10⁸ second or 21 years. If you place the panels 10x closer the the sun or concentrate light with mirrors you can recover the energy in 0.2 years instead. Assuming they do not melt.

...AGB (What that exactly means?) stars,

Asymtotic giant branch stars. Is the last phase in the life of a star with mass close to solar mass. The fusion rate is going so fast that it blows the shell out into space and forms planetary nebula. It is a red giant but different from the red giant stages. Totally unrelated to red dwarf or red supergiant but the same temperature. The sun should become an AGB star eventually. You have some choices for moving around an AGB star system using either electric and magnetic sails that deflect the stellar wind or you could sail with just pressure from the light.

For example the star Mira. It has 1.18 solar mass (so 1.18 solar gravity) and around 9000 solar luminosity. So in a Jupiter like orbit you still have more than 300 times the irradiance. You might be able to collect some of the matter in the solar wind. Mira is blowing out 3 x 10-7 solar mass per year. About 10% of Earth's mass annually. Mira has a companion white dwarf star which is accreting matter and may be forming new planets. Lots of material for solar panels and habitats.

...A mothership can transport kilotons of goods with energy of a few Tsar bombs, travel takes months... Or is it a bit plausible, that neutron stars, black holes, extreme conditions created some kind of unobtanium?

Okay, that stuff about fuel being food is just silly.

If you drop a 1 kilo brick of anything into a "large" white dwarf star it will be traveling over 6.3 x 10⁶ m/s and has kinetic energy 2 x 10¹³ J. If 1000 tons of materials appear and collide at that velocity you will have 10x the energy released if the cargo impacts something. If the mothership is much more massive than the cargo you could use that for energy generation too. The weapons potential would be significant. Diving into the black hole would give you much higher velocity.
You need to consider what velocities a ship has after leaving "hyperspace". Making a 180 rotation around the milky way from the sun would mean the ship is traveling 220 km/s in the opposite direction from surrounding stars, likely 440 km/s collision. Adjusting to the local velocity ads a lot of energy and might require reaction mass.

We could attach a 1 ton ram in front of the mother ship and make it look like a viking prow made of regolith. Then we place the cargo bay in the front of the mother ship but behind the ram. When we dive into a neutron star the ram will impact the surface at 1.5 x 10⁸ m/s (not adjusted for relativity) The ram gives the 2 x 10¹⁷ J energy we needed but the cargo bay can also pick up 1000 tons of neutron star surface material before jumping through hyperspace. The plasma remains of the mothership arrives at the target destination flying at 1 x 10⁸ m/s and carrying a kiloton of highly unstable neutronium. The neutronium would fission instantly.

In deep space you have better heat sinks than on earth. A warm ocean (perhaps under Chandra) could boil liquid nitrogen to drive a turbine. The mothership could crash into a deep camber and melt/boil a large volume of ice. The heavy metals from the neutron star and mothership plasma would eventually settle and could be collected. Free neutrons could produce more deuterium.

 

[Noisy Rhysling]

You missed my point. The "Food" issue on a robot ship is zero. The fuel is already in the calculations, you don't need to add it twice.

 

[GTOM]

You missed my point. The "Food" issue on a robot ship is zero. The fuel is already in the calculations, you don't need to add it twice.

The untrust factor is bigger, they don't like to give hypertechnology to AIs.

 

[Noisy Rhysling]

The untrust factor is bigger, they don't like to give hypertechnology to AIs.

Yeah, that's today. Tomorrow is always what we don't expect it to be.