Earth Space Elevators are not close and may never be

Peter Swan, president of International Space Elevator Consortium (ISEC), was quoted as saying that an Earth Based Space elevator could cost close to $10 billion to build and could reduce the cost of putting things into orbit from roughly $3,500 per pound today to as little as $25 per pound.

There is some carbon nanotube bundles that would be strong enough at 80 GPA of strength. However, there is less of this material than you would use to floss your teeth.

There will be a space experiment called the Space Tethered Autonomous Robotic Satellite–Mini elevator, or STARS-Me. It was devised by physicists from Japan’s Shizuoka University. They will 10-meter steel tether in space. This is like a toothpick bridge representing a proof of concept for a 100-mile long bridge. Again you do not have the equivalent of the 1000’s of tons of steel and cement.

The elevator car portion has not been proven beyond 1000 meters instead of the 50,000 kilometers.

The elevator cars have to go through the radiation belt.

If a fully reusable SpaceX BFR is built then 100 tons would be launched every time and only the cost of fuel would be needed. This would bring the cost of rockets down to $80 per kilogram launch cost ($32 per pound). A rocket system where construction has started, the engine is almost developed and some level of reusable rockets have been demonstrated has costs that are almost as good as a low-ball price estimate of a system where the technology does not exist.

The cost estimate of $10 billion for something 40,000 miles long. China spent $600 billion on high-speed rail lines using well-known technology and cement and steel from 2013-2017. China built shorter high-speed rail lines than the 40,000 mile length of the proposed space elevator.

No Space Elevator has ever been built and we have almost none of the required construction materials.

A 24-mile bridge was built in China for $2 billion. One mile long bridges in the US can cost $6.5 billion.

The $10 billion cost estimate seems like a silly and insane low-ball guess.

If the nanotechnology advances to make that much super-strong materials then vastly improved reusable rockets could be built or super cheap space planes would become possible that would be even lower cost than the proposed SpaceX BFR. The alternative advanced access to space would be cheaper than the space elevator using technology to make the space elevator possible.

We have the materials to make and deploy a lunar space elevator in one launch but we have not built it.

It seems the space elevator is an inferior design that is barely theoretically possible and which will not be less expensive.

188 thoughts on “Earth Space Elevators are not close and may never be”

  1. Could the anchors in orbit have counter-thrusters that apply less tension on the tether? Thus eliminating the need for an unrealistic tether strength?

    Disclaimer: I am ignorant of physics and engineering. Just interested, average-Joe.

    Reply
  2. Thank you for the welcome! 🙂 Your rebuttals have served to alleviate my two major concerns. That second point had been my main concern and I hadn’t considered a clamping system. I do think a space elevator would still have an operational lifespan. This lifespan would hopefully be several decades for the first elevator. If repairs extend that then I would view the lifespan as the time before repair costs exceed the initial construction costs. A certain minimum climbing speed would be required of the cars to allow the profits to keep up with the overhead. At this time there are likely too many unknown factors to make a good evaluation of what that climbing speed is. It is interesting to think about. Best regards, Peter

    Reply
  3. Thank you for the welcome! :)Your rebuttals have served to alleviate my two major concerns. That second point had been my main concern and I hadn’t considered a clamping system. I do think a space elevator would still have an operational lifespan. This lifespan would hopefully be several decades for the first elevator. If repairs extend that then I would view the lifespan as the time before repair costs exceed the initial construction costs. A certain minimum climbing speed would be required of the cars to allow the profits to keep up with the overhead. At this time there are likely too many unknown factors to make a good evaluation of what that climbing speed is. It is interesting to think about.Best regardsPeter

    Reply
  4. Thank you for the welcome! 🙂 Your rebuttals have served to alleviate my two major concerns. That second point had been my main concern and I hadn’t considered a clamping system. I do think a space elevator would still have an operational lifespan. This lifespan would hopefully be several decades for the first elevator. If repairs extend that then I would view the lifespan as the time before repair costs exceed the initial construction costs. A certain minimum climbing speed would be required of the cars to allow the profits to keep up with the overhead. At this time there are likely too many unknown factors to make a good evaluation of what that climbing speed is. It is interesting to think about. Best regards, Peter

    Reply
  5. Thank you for the welcome! :)Your rebuttals have served to alleviate my two major concerns. That second point had been my main concern and I hadn’t considered a clamping system. I do think a space elevator would still have an operational lifespan. This lifespan would hopefully be several decades for the first elevator. If repairs extend that then I would view the lifespan as the time before repair costs exceed the initial construction costs. A certain minimum climbing speed would be required of the cars to allow the profits to keep up with the overhead. At this time there are likely too many unknown factors to make a good evaluation of what that climbing speed is. It is interesting to think about.Best regardsPeter

    Reply
  6. Thank you for the welcome! 🙂

    Your rebuttals have served to alleviate my two major concerns. That second point had been my main concern and I hadn’t considered a clamping system. I do think a space elevator would still have an operational lifespan. This lifespan would hopefully be several decades for the first elevator. If repairs extend that then I would view the lifespan as the time before repair costs exceed the initial construction costs. A certain minimum climbing speed would be required of the cars to allow the profits to keep up with the overhead. At this time there are likely too many unknown factors to make a good evaluation of what that climbing speed is. It is interesting to think about.

    Best regards,
    Peter

    Reply
  7. It’s not the same at all . Mzso is right, a rail gun (using magnetics) could launch something into space (theoretically), but a mechanical catapult system has serious limitations. There’s a reason why catapults fell out of favor by the 1700’s. Even modern catapults (see the annual punkin chunkin contest) lose out to compressed air cannons. Not sure how an elevator relates to a catapult, you must be thinking of something else.

    Reply
  8. It’s not the same at all . Mzso is right a rail gun (using magnetics) could launch something into space (theoretically) but a mechanical catapult system has serious limitations. There’s a reason why catapults fell out of favor by the 1700’s. Even modern catapults (see the annual punkin chunkin contest) lose out to compressed air cannons. Not sure how an elevator relates to a catapult you must be thinking of something else.

    Reply
  9. LOL… LMAO That’s been disproven too. It would be designed to hold up the weight of the cable/structure that varies from 0G at geosynchronous orbit to 1G at the ends. Such an event as you’re describing would be hundreds or thousands of g’s, the structure would disintegrate into a million pieces that would fall thru the atmosphere, limiting its terminal velocity (terminal velocity of a human is about 100 mph, regardless if they fell from an airplane or a ten-story building). What’s more, since the whole structure is moving as fast as the Earth rotates, it would fall down largely in place, it would not “wrap itself around the Earth”.

    Reply
  10. LOL… LMAO That’s been disproven too. It would be designed to hold up the weight of the cable/structure that varies from 0G at geosynchronous orbit to 1G at the ends. Such an event as you’re describing would be hundreds or thousands of g’s the structure would disintegrate into a million pieces that would fall thru the atmosphere limiting its terminal velocity (terminal velocity of a human is about 100 mph regardless if they fell from an airplane or a ten-story building).What’s more since the whole structure is moving as fast as the Earth rotates it would fall down largely in place it would not wrap itself around the Earth””.”””

    Reply
  11. It’s not the same at all . Mzso is right, a rail gun (using magnetics) could launch something into space (theoretically), but a mechanical catapult system has serious limitations. There’s a reason why catapults fell out of favor by the 1700’s. Even modern catapults (see the annual punkin chunkin contest) lose out to compressed air cannons.

    Not sure how an elevator relates to a catapult, you must be thinking of something else.

    Reply
  12. LOL… LMAO

    That’s been disproven too. It would be designed to hold up the weight of the cable/structure that varies from 0G at geosynchronous orbit to 1G at the ends. Such an event as you’re describing would be hundreds or thousands of g’s, the structure would disintegrate into a million pieces that would fall thru the atmosphere, limiting its terminal velocity (terminal velocity of a human is about 100 mph, regardless if they fell from an airplane or a ten-story building).

    What’s more, since the whole structure is moving as fast as the Earth rotates, it would fall down largely in place, it would not “wrap itself around the Earth”.

    Reply
  13. The main reason there will be a lot of commerce from space to land is pretty simple (in economic terms). Division of labor and specialization: Until the population of space is a significant part of the population on Earth, the space economy will not be able to get enough people to specialize in every sector needed. Even if the space population has a mean IQ 20 points higher and a lot of capital per inhabitant than Earth’s they will require a lot of other figures like: surgeons, physician, engineers, and what not. To be a surgeon (or what not) you need to have at least a number of surgeons to retain the state of the art and advance it. In the US you have 46 Primary Care physicians / 100K inhabitants (and these are the bottom of the barrel, usually). So, if you have 100 K people in orbit, you needs at least 46 physicians doing the daily routines (not very complex stuff). What about neurosurgeons? Specialists in gastroenterology? Robotics can help, but 0.1 seconds lags from orbit to land is not easy for surgeons. Moon? 1 second lag. Mars? Better the robot do it without human help. Add the same for civil engineering to build homes, factories, farming, etc. They MUST be specialists if you want the best results. Do space colonies needs computer CPUs, GPUs, etc.? Do you think you can build a foundry in space for cheap and have it staffed by good personnel with 1 M people in orbit? On Mars?

    Reply
  14. The main reason there will be a lot of commerce from space to land is pretty simple (in economic terms).Division of labor and specialization:Until the population of space is a significant part of the population on Earth the space economy will not be able to get enough people to specialize in every sector needed.Even if the space population has a mean IQ 20 points higher and a lot of capital per inhabitant than Earth’s they will require a lot of other figures like: surgeons physician engineers and what not.To be a surgeon (or what not) you need to have at least a number of surgeons to retain the state of the art and advance it. In the US you have 46 Primary Care physicians / 100K inhabitants (and these are the bottom of the barrel usually).So if you have 100 K people in orbit you needs at least 46 physicians doing the daily routines (not very complex stuff). What about neurosurgeons? Specialists in gastroenterology?Robotics can help but 0.1 seconds lags from orbit to land is not easy for surgeons. Moon? 1 second lag.Mars? Better the robot do it without human help.Add the same for civil engineering to build homes factories farming etc. They MUST be specialists if you want the best results.Do space colonies needs computer CPUs GPUs etc.? Do you think you can build a foundry in space for cheap and have it staffed by good personnel with 1 M people in orbit? On Mars?

    Reply
  15. The main reason there will be a lot of commerce from space to land is pretty simple (in economic terms).
    Division of labor and specialization:

    Until the population of space is a significant part of the population on Earth, the space economy will not be able to get enough people to specialize in every sector needed.
    Even if the space population has a mean IQ 20 points higher and a lot of capital per inhabitant than Earth’s they will require a lot of other figures like: surgeons, physician, engineers, and what not.

    To be a surgeon (or what not) you need to have at least a number of surgeons to retain the state of the art and advance it. In the US you have 46 Primary Care physicians / 100K inhabitants (and these are the bottom of the barrel, usually).
    So, if you have 100 K people in orbit, you needs at least 46 physicians doing the daily routines (not very complex stuff). What about neurosurgeons? Specialists in gastroenterology?

    Robotics can help, but 0.1 seconds lags from orbit to land is not easy for surgeons. Moon? 1 second lag.
    Mars? Better the robot do it without human help.

    Add the same for civil engineering to build homes, factories, farming, etc. They MUST be specialists if you want the best results.

    Do space colonies needs computer CPUs, GPUs, etc.? Do you think you can build a foundry in space for cheap and have it staffed by good personnel with 1 M people in orbit? On Mars?

    Reply
  16. It would do more than come down like a stack of cards … the whiplash and acceleration effect as it wraps around the earth could bring the cable down at tremendous speed and energy creating a massive explosion in a ring around the earth. Such an event could kill millions and vaporize entire cities in its path. Yes, biggest terrorist target ever and not worth the risk imho.

    Reply
  17. It would do more than come down like a stack of cards … the whiplash and acceleration effect as it wraps around the earth could bring the cable down at tremendous speed and energy creating a massive explosion in a ring around the earth. Such an event could kill millions and vaporize entire cities in its path. Yes biggest terrorist target ever and not worth the risk imho.

    Reply
  18. The basic issue with mass drivers is that they’re infrastructure intensive. They only make sense economically if you have enormous traffic, but then you’re launching a couple metric tons every few minutes dirt cheap. It’s like railroads vs horse drawn wagons; Rail is phenomenally cheaper, but only if you have the traffic. I haven’t seen an economic analysis of how much a mass driver designed to have low enough acceleration for man rating would cost, but you’re talking about 5-600 kilometers of evacuated tube lined with driver coils to get the acceleration low enough that somebody in good health could endure it for 2-3 minutes. I mean, it’s enough hardware that you’d have economies of scale on the manufacture of the components for just one driver, but the price of the first one would be in the billions of dollars.

    Reply
  19. The basic issue with mass drivers is that they’re infrastructure intensive. They only make sense economically if you have enormous traffic but then you’re launching a couple metric tons every few minutes dirt cheap.It’s like railroads vs horse drawn wagons; Rail is phenomenally cheaper but only if you have the traffic.I haven’t seen an economic analysis of how much a mass driver designed to have low enough acceleration for man rating would cost but you’re talking about 5-600 kilometers of evacuated tube lined with driver coils to get the acceleration low enough that somebody in good health could endure it for 2-3 minutes. I mean it’s enough hardware that you’d have economies of scale on the manufacture of the components for just one driver but the price of the first one would be in the billions of dollars.

    Reply
  20. Ah, technically, I think it inherently works out the same, due to basic strength of materials considerations. OTOH, the static loading for the elevator does help a bit.

    Reply
  21. Ah technically I think it inherently works out the same due to basic strength of materials considerations. OTOH the static loading for the elevator does help a bit.

    Reply
  22. And it’ll come down like a stack of cards if someone throws a stick of dynamite inside on it… Best terrorist target ever…

    Reply
  23. And it’ll come down like a stack of cards if someone throws a stick of dynamite inside on it…Best terrorist target ever…

    Reply
  24. It would do more than come down like a stack of cards … the whiplash and acceleration effect as it wraps around the earth could bring the cable down at tremendous speed and energy creating a massive explosion in a ring around the earth. Such an event could kill millions and vaporize entire cities in its path. Yes, biggest terrorist target ever and not worth the risk imho.

    Reply
  25. The basic issue with mass drivers is that they’re infrastructure intensive. They only make sense economically if you have enormous traffic, but then you’re launching a couple metric tons every few minutes dirt cheap.

    It’s like railroads vs horse drawn wagons; Rail is phenomenally cheaper, but only if you have the traffic.

    I haven’t seen an economic analysis of how much a mass driver designed to have low enough acceleration for man rating would cost, but you’re talking about 5-600 kilometers of evacuated tube lined with driver coils to get the acceleration low enough that somebody in good health could endure it for 2-3 minutes. I mean, it’s enough hardware that you’d have economies of scale on the manufacture of the components for just one driver, but the price of the first one would be in the billions of dollars.

    Reply
  26. No matter how often proven safe, many people won’t care for the controlled explosions of a rocket. A slow and steady elevator, even if more expensive, will find an audience.

    Reply
  27. No matter how often proven safe many people won’t care for the controlled explosions of a rocket. A slow and steady elevator even if more expensive will find an audience.

    Reply
  28. Deorbiting stuff is relatively easy (compared to launching). But good point about the containers. In principle, they could be made of cheap disposable material, but I wouldn’t advise that, even though the mass is negligible compared to Earth’s mass. Carbon-based heat shields can survive reentry temperature even without ablation (depending on the specific material), so I’m not too worried about atmospheric pollution. The heat shield can be a relatively small fraction of the mass. But like I said, I wouldn’t advise this. Anyway, yes, eventually nearly all materials can be made in space. By mass, other than food, most of our production is steel and fossil fuels (mostly for energy). Other important metals and certain chemicals are an order of magnitude or two less, and everything else is much less still. Iron and other metals are plentiful in space, and space energy won’t be based on fossil fuels. But really, in the long term all we need is CHON, with small amounts of a few other elements. CHON are four of the most common elements out there. They can be fashioned into everything from construction materials (much stronger than steel) to food, water, air, chemicals, and even electronics. Granted, this will require some new manufacturing technologies, but until then, there’s plenty of more conventional materials in space (iron, other metals, silicates, and many others). And yes, food for space can be grown in space. The costs are prohibitive today precisely because launch from Earth is expensive. But I’m talking about a whole economy in space. Sure, it’ll take long time to build, but it can start small and expand gradually from there. And it can be bootstrapped with just BFRs.

    Reply
  29. Deorbiting stuff is relatively easy (compared to launching). But good point about the containers. In principle they could be made of cheap disposable material but I wouldn’t advise that even though the mass is negligible compared to Earth’s mass. Carbon-based heat shields can survive reentry temperature even without ablation (depending on the specific material) so I’m not too worried about atmospheric pollution. The heat shield can be a relatively small fraction of the mass. But like I said I wouldn’t advise this.Anyway yes eventually nearly all materials can be made in space. By mass other than food most of our production is steel and fossil fuels (mostly for energy). Other important metals and certain chemicals are an order of magnitude or two less and everything else is much less still. Iron and other metals are plentiful in space and space energy won’t be based on fossil fuels.But really in the long term all we need is CHON with small amounts of a few other elements. CHON are four of the most common elements out there. They can be fashioned into everything from construction materials (much stronger than steel) to food water air chemicals and even electronics. Granted this will require some new manufacturing technologies but until then there’s plenty of more conventional materials in space (iron other metals silicates and many others). And yes food for space can be grown in space.The costs are prohibitive today precisely because launch from Earth is expensive. But I’m talking about a whole economy in space. Sure it’ll take long time to build but it can start small and expand gradually from there. And it can be bootstrapped with just BFRs.

    Reply
  30. You are assuming that ANY material will be available and cheaper to get in space. You are assuming that ANY industry will be moved to space. You are assuming all food consumed in space will be made in space, without considering the economics of it. It’s somewhat like saying any country can just close off to the outside world. There will always be trade and goods moving between two places. And in quantities far in excess of what fleets of rockets can carry. Furthermore, why all that production in space? I guess it’s for Earth inhabitants, right? How will you de-orbit it all? I mean, heavy industry production. 30 million tons of steel per year imported in 2016 by the US alone. Let’s consider ALL INDUSTRIES and for ALL COUNTRIES on Earth. That’s a lot of stuff to de-orbit. Will we de-orbit all of those in containers with heat shields and parachutes or rocket propulsors? What about more sensitive material? And once those containers land… what do you do with ALL OF THEM? Containers are reused all the time. I suppose containers used to bring stuff from space industries to Earth’s surface would need to be taken back up. MILLIONS of them. Every month.

    Reply
  31. You are assuming that ANY material will be available and cheaper to get in space.You are assuming that ANY industry will be moved to space.You are assuming all food consumed in space will be made in space without considering the economics of it. It’s somewhat like saying any country can just close off to the outside world. There will always be trade and goods moving between two places. And in quantities far in excess of what fleets of rockets can carry.Furthermore why all that production in space? I guess it’s for Earth inhabitants right?How will you de-orbit it all? I mean heavy industry production. 30 million tons of steel per year imported in 2016 by the US alone.Let’s consider ALL INDUSTRIES and for ALL COUNTRIES on Earth.That’s a lot of stuff to de-orbit. Will we de-orbit all of those in containers with heat shields and parachutes or rocket propulsors? What about more sensitive material?And once those containers land… what do you do with ALL OF THEM? Containers are reused all the time.I suppose containers used to bring stuff from space industries to Earth’s surface would need to be taken back up. MILLIONS of them. Every month.

    Reply
  32. Bad analogy. The old and new worlds are much more symmetric in the amount of resources and in transportation requirements. In contrast, space has *orders of magnitude* more resources than Earth, and moving stuff in space is far easier than launching the same amount of stuff from Earth. The old and new worlds both need each other. But space doesn’t need Earth once it gets going (with the exception of some specialty products that can’t be made in space *yet*, like electronics; but the more space industry gets developed, the fewer such products there will be). Some long-term plans call for moving most heavy industry into space. What are we going to be launching then? And no, not the factories. They’ll be made from space resources too.

    Reply
  33. Bad analogy. The old and new worlds are much more symmetric in the amount of resources and in transportation requirements. In contrast space has *orders of magnitude* more resources than Earth and moving stuff in space is far easier than launching the same amount of stuff from Earth. The old and new worlds both need each other. But space doesn’t need Earth once it gets going (with the exception of some specialty products that can’t be made in space *yet* like electronics; but the more space industry gets developed the fewer such products there will be).Some long-term plans call for moving most heavy industry into space. What are we going to be launching then? And no not the factories. They’ll be made from space resources too.

    Reply
  34. The ecological consequences of many large launches are much smaller that some people think. You can calculate how much CO2 would be produced, and compare it to global CO2 production. IIRC, there’d have too be many many thousands of launches to leave the negligible zone. Mass drivers are not applicable to current trade. Shipping on an ocean surface is easy and cheap. Launching stuff out of Earth’s gravity well is much harder. I’ll leave the specifics up to the engineers – mass drivers may not be the best solution either. Limitations, off the top of my head: material strength vs cable size vs carrier size and number vs max carrier speed vs energy requirements vs desired throughput. Don’t know if it’s possible to balance all of these to get the desired throughput in a system of reasonable size (it also depends how much throughput is desired). I admit that maybe “physics” was too strong a word. But it is part of it.

    Reply
  35. The ecological consequences of many large launches are much smaller that some people think. You can calculate how much CO2 would be produced and compare it to global CO2 production. IIRC there’d have too be many many thousands of launches to leave the negligible zone.Mass drivers are not applicable to current trade. Shipping on an ocean surface is easy and cheap. Launching stuff out of Earth’s gravity well is much harder. I’ll leave the specifics up to the engineers – mass drivers may not be the best solution either.Limitations off the top of my head: material strength vs cable size vs carrier size and number vs max carrier speed vs energy requirements vs desired throughput. Don’t know if it’s possible to balance all of these to get the desired throughput in a system of reasonable size (it also depends how much throughput is desired). I admit that maybe physics”” was too strong a word. But it is part of it.”””

    Reply
  36. Imho, that argument is like saying that because the New World had all sorts of materials available, transatlantic commerce wouldn´t exist, or would only exist in small capacity.

    Reply
  37. Imho that argument is like saying that because the New World had all sorts of materials available transatlantic commerce wouldn´t exist or would only exist in small capacity.”

    Reply
  38. 500 tons capacity is also a small capacity. Again… airplanes to sea ships. What you said is that instead of Boeing 737, a Russian Antonov cargo plane could make sea ships obsolete. I don´t think so. And the reason is similar to why huge rockets won´t be used. They are still much pricier than sea ships per transported kg, need huge landing strips not available everywhere. Do we really want such large rockets taking off and landing all the time? Are there ecological consequences? Mass drivers? What % of current trade could be achieved if we had mass drivers right now? I mean, what kind of products, containers, etc, could be sent anywhere else using mass drivers? What sort of PHYSICS (not engineering) limitations will affect their capacity?

    Reply
  39. 500 tons capacity is also a small capacity. Again… airplanes to sea ships. What you said is that instead of Boeing 737 a Russian Antonov cargo plane could make sea ships obsolete. I don´t think so. And the reason is similar to why huge rockets won´t be used. They are still much pricier than sea ships per transported kg need huge landing strips not available everywhere.Do we really want such large rockets taking off and landing all the time? Are there ecological consequences? Mass drivers? What {22800fc54956079738b58e74e4dcd846757aa319aad70fcf90c97a58f3119a12} of current trade could be achieved if we had mass drivers right now? I mean what kind of products containers etc could be sent anywhere else using mass drivers?What sort of PHYSICS (not engineering) limitations will affect their capacity?”

    Reply
  40. One more thing – are we really going to need that big a lift capacity, ever? With just BFR, we can bootstrap an extensive space industry infrastructure. Then most space materials would come from space, not from Earth.

    Reply
  41. One more thing – are we really going to need that big a lift capacity ever? With just BFR we can bootstrap an extensive space industry infrastructure. Then most space materials would come from space not from Earth.

    Reply
  42. One error in your analysis is you’re comparing *future* space elevators to *current* rocket designs. The same materials that would enable a space elevator, should also enable much better rockets. By rough estimate, we could see something of similar size to BFR with a ~500 ton payload capacity (possibly single-stage). A somewhat larger rocket could lift 1000 tons per flight. With NTR, as were presented here on NBF (if they ever fly), plus such materials, you could maybe lift a few thousand tons per flight, with a much smaller explosion risk (well-designed nuclear rockets don’t explode – and don’t irradiate the atmosphere either, counter to common fears). Then there are other high-capacity cargo launch solutions, which have advantages over a space elevator. Brett mentioned mas drivers, which are one option. And to begin with, I’m not convinced a space elevator would have as big a capacity as you imagine. There are all sorts of physics limitations that affect its capacity.

    Reply
  43. One error in your analysis is you’re comparing *future* space elevators to *current* rocket designs. The same materials that would enable a space elevator should also enable much better rockets. By rough estimate we could see something of similar size to BFR with a ~500 ton payload capacity (possibly single-stage). A somewhat larger rocket could lift 1000 tons per flight.With NTR as were presented here on NBF (if they ever fly) plus such materials you could maybe lift a few thousand tons per flight with a much smaller explosion risk (well-designed nuclear rockets don’t explode – and don’t irradiate the atmosphere either counter to common fears).Then there are other high-capacity cargo launch solutions which have advantages over a space elevator. Brett mentioned mas drivers which are one option. And to begin with I’m not convinced a space elevator would have as big a capacity as you imagine. There are all sorts of physics limitations that affect its capacity.

    Reply
  44. Catapult? Don’t you mean rail gun? Because I don’t think a giant swinging arm is even less realistic material strength wise than a space elevator.

    Reply
  45. Catapult? Don’t you mean rail gun? Because I don’t think a giant swinging arm is even less realistic material strength wise than a space elevator.

    Reply
  46. The bible is very clear about the prospects of building a tower up to the heavens if everyone starts speaking the same language. Not a good idea.

    Reply
  47. The bible is very clear about the prospects of building a tower up to the heavens if everyone starts speaking the same language.Not a good idea.

    Reply
  48. Deorbiting stuff is relatively easy (compared to launching). But good point about the containers. In principle, they could be made of cheap disposable material, but I wouldn’t advise that, even though the mass is negligible compared to Earth’s mass. Carbon-based heat shields can survive reentry temperature even without ablation (depending on the specific material), so I’m not too worried about atmospheric pollution. The heat shield can be a relatively small fraction of the mass. But like I said, I wouldn’t advise this.

    Anyway, yes, eventually nearly all materials can be made in space. By mass, other than food, most of our production is steel and fossil fuels (mostly for energy). Other important metals and certain chemicals are an order of magnitude or two less, and everything else is much less still. Iron and other metals are plentiful in space, and space energy won’t be based on fossil fuels.

    But really, in the long term all we need is CHON, with small amounts of a few other elements. CHON are four of the most common elements out there. They can be fashioned into everything from construction materials (much stronger than steel) to food, water, air, chemicals, and even electronics. Granted, this will require some new manufacturing technologies, but until then, there’s plenty of more conventional materials in space (iron, other metals, silicates, and many others). And yes, food for space can be grown in space.

    The costs are prohibitive today precisely because launch from Earth is expensive. But I’m talking about a whole economy in space. Sure, it’ll take long time to build, but it can start small and expand gradually from there. And it can be bootstrapped with just BFRs.

    Reply
  49. You are assuming that ANY material will be available and cheaper to get in space.

    You are assuming that ANY industry will be moved to space.

    You are assuming all food consumed in space will be made in space, without considering the economics of it.

    It’s somewhat like saying any country can just close off to the outside world. There will always be trade and goods moving between two places. And in quantities far in excess of what fleets of rockets can carry.
    Furthermore, why all that production in space? I guess it’s for Earth inhabitants, right?

    How will you de-orbit it all? I mean, heavy industry production. 30 million tons of steel per year imported in 2016 by the US alone.

    Let’s consider ALL INDUSTRIES and for ALL COUNTRIES on Earth.

    That’s a lot of stuff to de-orbit. Will we de-orbit all of those in containers with heat shields and parachutes or rocket propulsors? What about more sensitive material?

    And once those containers land… what do you do with ALL OF THEM? Containers are reused all the time.

    I suppose containers used to bring stuff from space industries to Earth’s surface would need to be taken back up. MILLIONS of them. Every month.

    Reply
  50. If Starlink is huge, and everything goes right for Space X, launching 1 BFR per day is not outside the realm of possibility.

    Reply
  51. If Starlink is huge and everything goes right for Space X launching 1 BFR per day is not outside the realm of possibility.

    Reply
  52. Yeah and you’re going to blow through your propellant budget doing those moves, satellite operators would be furious, it would cut the lifetime of their satellites in half or more. with a 90 minutes transit time, you might have to avoid that thing a dozen times a day, depending on the orbit. A lot of that will have to be manual, suddenly you have satellite operators working full time just to avoid this tether? Because most satellites that are up when you build this thing won’t have automated software capable of detecting that it’s going to collide with it. You’re talking about like networking NASA Deep Space Radar or some other kind of orbital determination system (because by the way, we don’t bother to literally look and see where every satellite is at any given moment, it’s involved and unnecessary, and often times not possible, you just have a box, you don’t really know for sure where in that box it is). This activity of “oh, all 12000 satellites in LEO are going to have to avoid this thing now”, first of all is way harder than you make it sound and way more involved, and you also will have dead birds up there you can’t move, which will hit the thing. It’ll be hit by micrometeoroids, the debatable aspect is at what frequency and how much will it impact structural integrity, and how will you assess its lifetime and its damage. Will you find out when your carriage of 80,000 tons of material comes plummeting back down?

    Reply
  53. Yeah and you’re going to blow through your propellant budget doing those moves satellite operators would be furious it would cut the lifetime of their satellites in half or more. with a 90 minutes transit time you might have to avoid that thing a dozen times a day depending on the orbit. A lot of that will have to be manual suddenly you have satellite operators working full time just to avoid this tether? Because most satellites that are up when you build this thing won’t have automated software capable of detecting that it’s going to collide with it. You’re talking about like networking NASA Deep Space Radar or some other kind of orbital determination system (because by the way we don’t bother to literally look and see where every satellite is at any given moment it’s involved and unnecessary and often times not possible you just have a box you don’t really know for sure where in that box it is). This activity of oh”” all 12000 satellites in LEO are going to have to avoid this thing now””” first of all is way harder than you make it sound and way more involved and you also will have dead birds up there you can’t move which will hit the thing.It’ll be hit by micrometeoroids the debatable aspect is at what frequency and how much will it impact structural integrity and how will you assess its lifetime and its damage. Will you find out when your carriage of 80″”000 tons of material comes plummeting back down?”””

    Reply
  54. Bad analogy. The old and new worlds are much more symmetric in the amount of resources and in transportation requirements. In contrast, space has *orders of magnitude* more resources than Earth, and moving stuff in space is far easier than launching the same amount of stuff from Earth. The old and new worlds both need each other. But space doesn’t need Earth once it gets going (with the exception of some specialty products that can’t be made in space *yet*, like electronics; but the more space industry gets developed, the fewer such products there will be).

    Some long-term plans call for moving most heavy industry into space. What are we going to be launching then? And no, not the factories. They’ll be made from space resources too.

    Reply
  55. The ecological consequences of many large launches are much smaller that some people think. You can calculate how much CO2 would be produced, and compare it to global CO2 production. IIRC, there’d have too be many many thousands of launches to leave the negligible zone.

    Mass drivers are not applicable to current trade. Shipping on an ocean surface is easy and cheap. Launching stuff out of Earth’s gravity well is much harder. I’ll leave the specifics up to the engineers – mass drivers may not be the best solution either.

    Limitations, off the top of my head: material strength vs cable size vs carrier size and number vs max carrier speed vs energy requirements vs desired throughput. Don’t know if it’s possible to balance all of these to get the desired throughput in a system of reasonable size (it also depends how much throughput is desired). I admit that maybe “physics” was too strong a word. But it is part of it.

    Reply
  56. 500 tons capacity is also a small capacity. Again… airplanes to sea ships. What you said is that instead of Boeing 737, a Russian Antonov cargo plane could make sea ships obsolete.

    I don´t think so. And the reason is similar to why huge rockets won´t be used. They are still much pricier than sea ships per transported kg, need huge landing strips not available everywhere.
    Do we really want such large rockets taking off and landing all the time? Are there ecological consequences?
    Mass drivers? What % of current trade could be achieved if we had mass drivers right now? I mean, what kind of products, containers, etc, could be sent anywhere else using mass drivers?
    What sort of PHYSICS (not engineering) limitations will affect their capacity?

    Reply
  57. One more thing – are we really going to need that big a lift capacity, ever? With just BFR, we can bootstrap an extensive space industry infrastructure. Then most space materials would come from space, not from Earth.

    Reply
  58. One error in your analysis is you’re comparing *future* space elevators to *current* rocket designs. The same materials that would enable a space elevator, should also enable much better rockets. By rough estimate, we could see something of similar size to BFR with a ~500 ton payload capacity (possibly single-stage). A somewhat larger rocket could lift 1000 tons per flight.

    With NTR, as were presented here on NBF (if they ever fly), plus such materials, you could maybe lift a few thousand tons per flight, with a much smaller explosion risk (well-designed nuclear rockets don’t explode – and don’t irradiate the atmosphere either, counter to common fears).

    Then there are other high-capacity cargo launch solutions, which have advantages over a space elevator. Brett mentioned mas drivers, which are one option. And to begin with, I’m not convinced a space elevator would have as big a capacity as you imagine. There are all sorts of physics limitations that affect its capacity.

    Reply
  59. I believe it’s WAYYY more feasable, and orders of magniture cheaper and faster to deploy to just catapult bulk materials into space. Thinking about metals, soil, water, propellants… the are the main weight component (and thus the main cuplit of the stellar costs involved) in space colonization. A robust and reliable catapult system could reload in munites, been EXTREMELY cheap, and sufficiently versatile for different types of materials. Combined witht the evolution on 3D printing in micro gravity envrionments, and advanced robotics, it will be possible to start build directly in the space most of the complex structure, and use high cost, rocket launched materials only when is strictily needed. Besides, some clever engineering could use some of the principles of the “space elevator” to – lanuch the item from as above as possible – calculate with extreme precision the trajectory (some limited direcionality of the containers might help – collimate the arriving items in a orbiting “tube” that electromagnetically slow down the objects (recovering the kinetic energy into electricity) and finally safely park the payload Cool!!!

    Reply
  60. I believe it’s WAYYY more feasable and orders of magniture cheaper and faster to deploy to just catapult bulk materials into space. Thinking about metals soil water propellants… the are the main weight component (and thus the main cuplit of the stellar costs involved) in space colonization.A robust and reliable catapult system could reload in munites been EXTREMELY cheap and sufficiently versatile for different types of materials.Combined witht the evolution on 3D printing in micro gravity envrionments and advanced robotics it will be possible to start build directly in the space most of the complex structure and use high cost rocket launched materials only when is strictily needed.Besides some clever engineering could use some of the principles of the space elevator”” to – lanuch the item from as above as possible- calculate with extreme precision the trajectory (some limited direcionality of the containers might help- collimate the arriving items in a orbiting “”””tube”””” that electromagnetically slow down the objects (recovering the kinetic energy into electricity) and finally safely park the payloadCool!!!”””

    Reply
  61. Energy storage would be distributed along the track; You have a series of storage capacitors and inductive drive rings, with the values chosen in advance so that they’d “ring” at the frequency needed to match the payload’s velocity over that part of the track. As the payload arrives, a capacitor dumps its load into a drive coil, which ramps up, and then either rings for a few cycles, or at peak current is switched to finish charging the next capacitor in the series, which then dumps into the next coil, chasing the payload along. The energy is stored in these drive capacitors, distributed along the track. Mind, that’s only for the high speed part. You’d likely start out with drive wheels run by motors, until the speed got up too high for the wheels to be practical, then a section of drive coils fed 3 phase, and then finally the capacitor driven section. Because, of course, the power required to achieve 6 gs acceleration increases with the speed…

    Reply
  62. Energy storage would be distributed along the track; You have a series of storage capacitors and inductive drive rings with the values chosen in advance so that they’d ring”” at the frequency needed to match the payload’s velocity over that part of the track. As the payload arrives”” a capacitor dumps its load into a drive coil which ramps up and then either rings for a few cycles or at peak current is switched to finish charging the next capacitor in the series which then dumps into the next coil chasing the payload along.The energy is stored in these drive capacitors distributed along the track.Mind that’s only for the high speed part. You’d likely start out with drive wheels run by motors until the speed got up too high for the wheels to be practical then a section of drive coils fed 3 phase and then finally the capacitor driven section.Because of course”” the power required to achieve 6 gs acceleration increases with the speed…”””

    Reply
  63. Catapult? Don’t you mean rail gun? Because I don’t think a giant swinging arm is even less realistic material strength wise than a space elevator.

    Reply
  64. I’ve always loved mass drivers. Ultimate in efficiency. … 70% of the things would be payload. … 10% to packaging. … 20% to circularizing rocketry. Solid rocket, most likely. It seemed like the perfect thing to install in someplace equatorial. Like, hmmm… oh, … Ecuador? Has mountains, too. (1.1) … d = ½at² (1.2) … v = at … t = v/a therefore (1.3) … d = v²/2a and by inversion solving for (a) (1.4) … a = v²/2d (2.1) … v is about 8,000 m/s (2.2) … d is 500 km (2.3) … a = 8,000² ÷ 2×500,000 (2.4) … a = 64 m/s² (64 ÷ 9.81 → 6.5 Gs) Yep! We’re definitely on the same page. If the investment energy goes at least η=75% into the whole enchilada, then… (3.1) … E = mv²/2η (3.2) … E = 2500 × 8000² ÷ 2 × 0.75 (3.3) … E = 107,000,000,000 joules (3.4) … E → 30,000 kWh … • $0.15 per kWh = $4,500 a launch in electricity. (4.1) … t = v/a = 8000 ÷ 64 (4.2) … t → 125 sec or 2 minutes To lob 70% of 2500 kg or $2.57 per kg in electricity. However, like the Elon Musk analysis, there’s a lot of infrastructure to fund. Indefinitely. And the NOT insignificant problem of how to store a hundred billion joules and deliver it in a progressive power ramp in about 2 total minutes to the 500 km track. Its an interesting problem in its own right. You’d certainly want to have a 100 megawatt generator driving it, so as to be able to lob every 20 minutes or so, around the clock. Could deliver well over 126,000 kg to orbit a day from one well run mass thrower. That’s over 1 BFR’s worth or so, per day. GoatGuy

    Reply
  65. I’ve always loved mass drivers. Ultimate in efficiency. … 70{22800fc54956079738b58e74e4dcd846757aa319aad70fcf90c97a58f3119a12} of the things would be payload. … 10{22800fc54956079738b58e74e4dcd846757aa319aad70fcf90c97a58f3119a12} to packaging. … 20{22800fc54956079738b58e74e4dcd846757aa319aad70fcf90c97a58f3119a12} to circularizing rocketry. Solid rocket most likely. It seemed like the perfect thing to install in someplace equatorial. Like hmmm… oh … Ecuador? Has mountains too. (1.1) … d = ½at²(1.2) … v = at … t = v/a therefore(1.3) … d = v²/2a and by inversion solving for (a)(1.4) … a = v²/2d(2.1) … v is about 8000 m/s(2.2) … d is 500 km(2.3) … a = 8000² ÷ 2×500000 (2.4) … a = 64 m/s² (64 ÷ 9.81 → 6.5 Gs)Yep! We’re definitely on the same page. If the investment energy goes at least η=75{22800fc54956079738b58e74e4dcd846757aa319aad70fcf90c97a58f3119a12} into the whole enchilada then…(3.1) … E = mv²/2η(3.2) … E = 2500 × 8000² ÷ 2 × 0.75(3.3) … E = 107000000000 joules(3.4) … E → 30000 kWh … • $0.15 per kWh = $4500 a launch in electricity. (4.1) … t = v/a = 8000 ÷ 64(4.2) … t → 125 sec or 2 minutesTo lob 70{22800fc54956079738b58e74e4dcd846757aa319aad70fcf90c97a58f3119a12} of 2500 kg or $2.57 per kg in electricity. However like the Elon Musk analysis there’s a lot of infrastructure to fund.Indefinitely. And the NOT insignificant problem of how to store a hundred billion joules and deliver it in a progressive power ramp in about 2 total minutes to the 500 km track. Its an interesting problem in its own right. You’d certainly want to have a 100 megawatt generator driving it so as to be able to lob every 20 minutes or so around the clock. Could deliver well over 126000 kg to orbit a day from one well run mass thrower. That’s over 1 BFR’s worth or so per day.GoatGuy”

    Reply
  66. Even with a vast cargo capacity needed, for bulk cargo you’d probably launch using a mass driver. That’s my opinion, anyway.

    Reply
  67. Even with a vast cargo capacity needed for bulk cargo you’d probably launch using a mass driver. That’s my opinion anyway.

    Reply
  68. Will the return of investment be bad if Space Elevators are built WHEN carbon nanotubes are 100-1000 times cheaper than now, as well as BFR price to orbit gets as low as $80/kg? AND if we only build the Space Elevator once we have a thriving space economy in desperate need of haul mass transportation of products to and from Earth? Don´t imagine tiny elevators carrying people up and down. Imagine the elevator cars as vertical Emma Maersks, Barzans, Knock Nevis’, etc… a few of them going up and a few going down at the same time, at small speeds, getting 2-3 weeks to reach the other end of the cable, each one some 1 week ahead of the other.

    Reply
  69. Will the return of investment be bad if Space Elevators are built WHEN carbon nanotubes are 100-1000 times cheaper than now as well as BFR price to orbit gets as low as $80/kg?AND if we only build the Space Elevator once we have a thriving space economy in desperate need of haul mass transportation of products to and from Earth?Don´t imagine tiny elevators carrying people up and down.Imagine the elevator cars as vertical Emma Maersks Barzans Knock Nevis’ etc… a few of them going up and a few going down at the same time at small speeds getting 2-3 weeks to reach the other end of the cable each one some 1 week ahead of the other.”

    Reply
  70. Quite the superficial analysis, imho. I don´t think anybody disagrees space elevators are unfeasible now due to technology AND economics. From that, saying they may never be feasible? 1 – Carbon nanotubes have been improving. We are able to produce better and more than 10 years ago. Where will we be in 10 years? 2 – The lift tests are mostly based on transmitting power to the climbers. Through the use of lasers for example. However, carbon nanotubes are an awesome electricity transmitter. I won´t be surprised if in future, it’s the cables of the Space Elevators themselves transmitting power to the climbers. 3 – The Van Allen belts are argument against HUMAN transportation AND/OR thin walled climber cars. I don´t see Space Elevators as being used to transport people, specially due to the long transit times 4 – The argument about BFRs becoming cheap enough is soooooo poor. It’s like saying that cheap airplanes would end with ocean liners. The cheaper cost might mean they (or other rockets) will be the prefered method for humans to travelling to orbit. Where paying twice the price per kg of a space elevator is worth considering you get there much faster. Its an planes vs ships argument really. For moving millions of tons in space, you will want a system much CHEAPER. Specially if the material being moved is not that expensive. The cost of transport being more expensive than the material itself is a big no-no. It will prove unfeasible to launch 666 BFR flights to carry only 100 thousand tons into space. Each of those BFR flights having the explosive power of a small atomic bomb (like N1 rocket), doing LOTS of noise, having a risk of failure associated with each take-off and landing (like an airplane do). The price of the Space Elevator might fall due to BFR itself being able to carry 150 tons of carbon nanotube threads to space with each flight. And yet, it still won´t be worth to build the Space Elevator. It will be feasible WHEN we have a thriving space ec

    Reply
  71. Quite the superficial analysis imho. I don´t think anybody disagrees space elevators are unfeasible now due to technology AND economics. From that saying they may never be feasible? 1 – Carbon nanotubes have been improving. We are able to produce better and more than 10 years ago. Where will we be in 10 years?2 – The lift tests are mostly based on transmitting power to the climbers. Through the use of lasers for example. However carbon nanotubes are an awesome electricity transmitter. I won´t be surprised if in future it’s the cables of the Space Elevators themselves transmitting power to the climbers.3 – The Van Allen belts are argument against HUMAN transportation AND/OR thin walled climber cars. I don´t see Space Elevators as being used to transport people specially due to the long transit times4 – The argument about BFRs becoming cheap enough is soooooo poor. It’s like saying that cheap airplanes would end with ocean liners. The cheaper cost might mean they (or other rockets) will be the prefered method for humans to travelling to orbit. Where paying twice the price per kg of a space elevator is worth considering you get there much faster.Its an planes vs ships argument really. For moving millions of tons in space you will want a system much CHEAPER. Specially if the material being moved is not that expensive. The cost of transport being more expensive than the material itself is a big no-no.It will prove unfeasible to launch 666 BFR flights to carry only 100 thousand tons into space. Each of those BFR flights having the explosive power of a small atomic bomb (like N1 rocket) doing LOTS of noise having a risk of failure associated with each take-off and landing (like an airplane do).The price of the Space Elevator might fall due to BFR itself being able to carry 150 tons of carbon nanotube threads to space with each flight.And yet it still won´t be worth to build the Space Elevator. It will be feasible WHEN we have a thri

    Reply
  72. I think aside from the technical challenges, the thing that will kill it will be return on investment. Has anyone looked into EM catapult as a means to send tonnage to space? This is much more proven technology that could be built in the near future.

    Reply
  73. I think aside from the technical challenges the thing that will kill it will be return on investment. Has anyone looked into EM catapult as a means to send tonnage to space? This is much more proven technology that could be built in the near future.

    Reply
  74. Rotavators seem a lot easier and realistic. They can be used in both directions and will gain momentum when deorbiting stuff. Should be possible to build a one-stage rocket that can dock with a rotavator. Perhaps something can be gained by staging rotavators too.

    Reply
  75. Rotavators seem a lot easier and realistic. They can be used in both directions and will gain momentum when deorbiting stuff. Should be possible to build a one-stage rocket that can dock with a rotavator. Perhaps something can be gained by staging rotavators too.

    Reply
  76. Agreed, we do not have the technology to build one around the Earth, but building one around the moon can be done today from a technical standpoint according to Isaac Arthur. He prefers a rotovator method for Earth. If you have never watched his Youtube series, for practical engineering and physics led futurism he is really hard to beat.

    Reply
  77. Agreed we do not have the technology to build one around the Earth but building one around the moon can be done today from a technical standpoint according to Isaac Arthur. He prefers a rotovator method for Earth. If you have never watched his Youtube series for practical engineering and physics led futurism he is really hard to beat.

    Reply
  78. Lots of people can’t see what happens after the Second Coming either. and for the same reason: it’s religious eschatology.

    Reply
  79. Lots of people can’t see what happens after the Second Coming either. and for the same reason: it’s religious eschatology.

    Reply
  80. Biggest problem, after material strength, is that you spend so long going through the Van Allen belts. 5-6 g acceleration, 500 km long mass driver in an evacuated tube ending at the top of a mountain, (Traditionally, it would be Pikes Peak.) with a really fast door at the top. No need to push material science, you emerge with enough speed to just need a circularizing burn at apogee. Throughput could be enormous.

    Reply
  81. Biggest problem after material strength is that you spend so long going through the Van Allen belts.5-6 g acceleration 500 km long mass driver in an evacuated tube ending at the top of a mountain (Traditionally it would be Pikes Peak.) with a really fast door at the top. No need to push material science you emerge with enough speed to just need a circularizing burn at apogee. Throughput could be enormous.

    Reply
  82. More than the engineering challenge there is the financial challenge. The capital cost of a space elevator would required far more traffic than current traffic. The BFR is the better solution for now.

    Reply
  83. More than the engineering challenge there is the financial challenge. The capital cost of a space elevator would required far more traffic than current traffic. The BFR is the better solution for now.

    Reply
  84. Its kind of interesting … working out the numbers from scratch, and seeing what their effect is on the overall cost of “doing a run”. Certainly — we can debate MY choices, but given: … LOX = $1.50/kg … LME = $2.06/kg … Fuel:Ox blend = $1.61/kg (from stochiometry) … STACK 1 ISP = 370 … STACK 2 ISP = 430 Working backward from stack № 2 to 1: № 2: … Payload = 100,000 kg, 25% of stack … Fuels = 280,000 kg, 70% stack … Structural = 20,000 kg, 5% stack № 1: … Payload = 400,000 kg, 15% stack … Fuels = 2,053,000 kg, 77% stack … Structural = 213,000 kg, 8% stack There are NO hard numbers as to the cost(s) of making first and second stages. Handwaving at best. But still its not hard to come up with defensible guesstimates. № 1: … cost per unit: $100,000,000 … number of uses per: 25 Per run: … cost recertify: 5% = $5,000,000 … cost fuel: $3,309,000 … cost ground sup: $1,000,000 … cost spaceport: $500,000 … cost insurance: $1,000,000 … cost admin: $500,000 … cost research: $5,000,000 (share of…) … cost crewing: $375,000 … cost PROFIT: $25,000,000 (only 33% margin!) … cost mort/use: $4,007,000 № 2: … cost per unit: $40,000,000 … number of uses per: 10 Per run: … cost recertify: 5% = $2,000,000 … cost fuel: $450,000 … cost ground sup: $250,000 … cost spaceport: $0 … cost insurance: $500,000 … cost admin: $1,250,000 … cost research: $5,000,000 (share of…) … cost crewing: $625,000 … cost PROFIT: $10,000,000 (33% total margin) … cost mort/use: $3,998,000 TOTAL: $69,000,000 per run cost $26.12 per kilogram (combined stacks, at takeoff) $700 per kg, of the 100,000 kg payload to orbit. Even when I make “number of uses” 999 for each, the cost only goes down to $620/kg. Simply, there’s a lot wrapped up in profit margin, ongoing research facility funding, and combined operational costs. The cost of fuel is insignificant. Just saying. Cherry cool-aid with vodka. GoatGuy

    Reply
  85. Its kind of interesting … working out the numbers from scratch and seeing what their effect is on the overall cost of doing a run””. Certainly — we can debate MY choices”” but given:… LOX = $1.50/kg… LME = $2.06/kg… Fuel:Ox blend = $1.61/kg (from stochiometry)… STACK 1 ISP = 370… STACK 2 ISP = 430Working backward from stack № 2 to 1:№ 2:… Payload = 100000 kg 25{22800fc54956079738b58e74e4dcd846757aa319aad70fcf90c97a58f3119a12} of stack… Fuels = 280000 kg 70{22800fc54956079738b58e74e4dcd846757aa319aad70fcf90c97a58f3119a12} stack… Structural = 20000 kg 5{22800fc54956079738b58e74e4dcd846757aa319aad70fcf90c97a58f3119a12} stack№ 1:… Payload = 400000 kg 15{22800fc54956079738b58e74e4dcd846757aa319aad70fcf90c97a58f3119a12} stack… Fuels = 253000 kg 77{22800fc54956079738b58e74e4dcd846757aa319aad70fcf90c97a58f3119a12} stack… Structural = 213000 kg 8{22800fc54956079738b58e74e4dcd846757aa319aad70fcf90c97a58f3119a12} stackThere are NO hard numbers as to the cost(s) of making first and second stages. Handwaving at best. But still its not hard to come up with defensible guesstimates.№ 1:… cost per unit: $1000000… number of uses per: 25Per run:… cost recertify: 5{22800fc54956079738b58e74e4dcd846757aa319aad70fcf90c97a58f3119a12} = $50000… cost fuel: $3309000… cost ground sup: $10000… cost spaceport: $500000… cost insurance: $10000… cost admin: $500000… cost research: $50000 (share of…)… cost crewing: $375000… cost PROFIT: $250000 (only 33{22800fc54956079738b58e74e4dcd846757aa319aad70fcf90c97a58f3119a12} margin!)… cost mort/use: $47000№ 2:… cost per unit: $400000… number of uses per: 10Per run:… cost recertify: 5{22800fc54956079738b58e74e4dcd846757aa319aad70fcf90c97a58f3119a12} = $20000… cost fuel: $450000… cost ground sup: $250000… cost spaceport: $0… cost insurance: $500000… cost admin: $1250000… cost research: $50000 (share of…)… cost crewing: $625000… cost PROFIT: $100″

    Reply
  86. I think they’ve solved that particular issue with the Hoytether design that fails gracefully under “micro” meteor bombardment. Larger meteors could be an issue. However, even solving the technical issues, (And I don’t think graphene or carbon nanotubes are quite up to the challenge.) I don’t see how anything so vulnerable to attack, and so valuable, could endure in the face of modern terrorism. Space elevators are something a *peaceful* society might build, not ours. I think there are probably better high tech, non-rocket approaches to mass transit to orbit, such as a really large mass driver (200 km long through an evacuated tube ending at the top of a mountain.) that can be better secured.

    Reply
  87. I think they’ve solved that particular issue with the Hoytether design that fails gracefully under micro”” meteor bombardment. Larger meteors could be an issue.However”” even solving the technical issues (And I don’t think graphene or carbon nanotubes are quite up to the challenge.) I don’t see how anything so vulnerable to attack and so valuable could endure in the face of modern terrorism. Space elevators are something a *peaceful* society might build not ours.I think there are probably better high tech non-rocket approaches to mass transit to orbit”” such as a really large mass driver (200 km long through an evacuated tube ending at the top of a mountain.) that can be better secured.”””

    Reply
  88. Yeah and you’re going to blow through your propellant budget doing those moves, satellite operators would be furious, it would cut the lifetime of their satellites in half or more. with a 90 minutes transit time, you might have to avoid that thing a dozen times a day, depending on the orbit. A lot of that will have to be manual, suddenly you have satellite operators working full time just to avoid this tether? Because most satellites that are up when you build this thing won’t have automated software capable of detecting that it’s going to collide with it. You’re talking about like networking NASA Deep Space Radar or some other kind of orbital determination system (because by the way, we don’t bother to literally look and see where every satellite is at any given moment, it’s involved and unnecessary, and often times not possible, you just have a box, you don’t really know for sure where in that box it is). This activity of “oh, all 12000 satellites in LEO are going to have to avoid this thing now”, first of all is way harder than you make it sound and way more involved, and you also will have dead birds up there you can’t move, which will hit the thing.

    It’ll be hit by micrometeoroids, the debatable aspect is at what frequency and how much will it impact structural integrity, and how will you assess its lifetime and its damage. Will you find out when your carriage of 80,000 tons of material comes plummeting back down?

    Reply
  89. The Van Allen belts can be eliminated, and likely someday will if there is exoindustrialization. The downside? It may cut into aroral displays.

    Reply
  90. The Van Allen belts can be eliminated and likely someday will if there is exoindustrialization. The downside? It may cut into aroral displays.

    Reply
  91. You say there’s time enough to move the tether, but what about the energy required to move the mass of the whole ‘tang? If you’re trying to move the tether by pushing at the point along its’ length that an object would impact, then you’re pull up and down on the tether. You’d a need a pretty big tug to move that kind of mass. And that would also put a crap load of stress and strain on the material If you’re doing it by dragging the rock-at-the-top from side to side; again a purtty big tug. That would be a dance and a half! I suppose one way of not needing to move the top rock around all the time is to build in a bit of slack right from the git-go, then the right algorithm could allow for the tether to be set into motion with one big pluck, flopping around it’s axis, needing only occasional adjustments, as it dodges bullets. Bull-whip. I see three or four large pincers at the ends of long arms, extending down from the terminal, positioned around the tether, taking turns grabbing onto, pulling out and letting go, playing the tether like a one-string bass. Elevator music. It’s like when I’m out moving the sprinkler in the yard, I’ll give the hose a little flip to send a wave down the line, timed to reach just the right spot along its’ length at the right time so the hose doesn’t get caught on a rock. Except my hose isn’t 20,000 miles long, X times more massive than one elephant, nor in need of a never ending freestyle jam session, flawlessly played.

    Reply
  92. You say there’s time enough to move the tether but what about the energy required to move the mass of the whole ‘tang? If you’re trying to move the tether by pushing at the point along its’ length that an object would impact then you’re pull up and down on the tether. You’d a need a pretty big tug to move that kind of mass. And that would also put a crap load of stress and strain on the materialIf you’re doing it by dragging the rock-at-the-top from side to side; again a purtty big tug. That would be a dance and a half! I suppose one way of not needing to move the top rock around all the time is to build in a bit of slack right from the git-go then the right algorithm could allow for the tether to be set into motion with one big pluck flopping around it’s axis needing only occasional adjustments as it dodges bullets. Bull-whip.I see three or four large pincers at the ends of long arms extending down from the terminal positioned around the tether taking turns grabbing onto pulling out and letting go playing the tether like a one-string bass.Elevator music.It’s like when I’m out moving the sprinkler in the yard I’ll give the hose a little flip to send a wave down the line timed to reach just the right spot along its’ length at the right time so the hose doesn’t get caught on a rock. Except my hose isn’t 20000 miles long X times more massive than one elephant nor in need of a never ending freestyle jam session flawlessly played.

    Reply
  93. I believe it’s WAYYY more feasable, and orders of magniture cheaper and faster to deploy to just catapult bulk materials into space. Thinking about metals, soil, water, propellants… the are the main weight component (and thus the main cuplit of the stellar costs involved) in space colonization.
    A robust and reliable catapult system could reload in munites, been EXTREMELY cheap, and sufficiently versatile for different types of materials.
    Combined witht the evolution on 3D printing in micro gravity envrionments, and advanced robotics, it will be possible to start build directly in the space most of the complex structure, and use high cost, rocket launched materials only when is strictily needed.
    Besides, some clever engineering could use some of the principles of the “space elevator” to
    – lanuch the item from as above as possible
    – calculate with extreme precision the trajectory (some limited direcionality of the containers might help
    – collimate the arriving items in a orbiting “tube” that electromagnetically slow down the objects (recovering the kinetic energy into electricity) and finally safely park the payload

    Cool!!!

    Reply
  94. An Earth elevator is almost not possible – for technical, safety and political reasons. But its quite easy on the Moon and could be done on Mars. However, there is still a huge safety issue. Space elevators are super vulnerable against micrometeorits.

    Reply
  95. An Earth elevator is almost not possible – for technical safety and political reasons. But its quite easy on the Moon and could be done on Mars. However there is still a huge safety issue. Space elevators are super vulnerable against micrometeorits.

    Reply
  96. Comparing Space Elevators with Rockets is like comparing a railroad (or a canal system) with cars and trucks. Space Elevators are not cost effective when the cargo is small in size,mass, the total tonnage/year is small and the delivery is not continuous.. They will become more interesting when the cargo moving up and down will increase and the needs for large payload will increase as well. A Space Elevator can be built large enough for every possible cargo (E.G. large like a oil tanker). The point about satellite debris are not very pertinent because bigger rockets, and the Space Elevator itself, will allow larger satellites to be deployed and maintained. reducing the need of many small satellites with a short life span. A satellite platform for telecommunication 10 m large (no solar panels included) could take the place of hundred small satellites easily.

    Reply
  97. Comparing Space Elevators with Rockets is like comparing a railroad (or a canal system) with cars and trucks.Space Elevators are not cost effective when the cargo is small in sizemass the total tonnage/year is small and the delivery is not continuous..They will become more interesting when the cargo moving up and down will increase and the needs for large payload will increase as well.A Space Elevator can be built large enough for every possible cargo (E.G. large like a oil tanker).The point about satellite debris are not very pertinent because bigger rockets and the Space Elevator itself will allow larger satellites to be deployed and maintained. reducing the need of many small satellites with a short life span.A satellite platform for telecommunication 10 m large (no solar panels included) could take the place of hundred small satellites easily.

    Reply
  98. Energy storage would be distributed along the track; You have a series of storage capacitors and inductive drive rings, with the values chosen in advance so that they’d “ring” at the frequency needed to match the payload’s velocity over that part of the track. As the payload arrives, a capacitor dumps its load into a drive coil, which ramps up, and then either rings for a few cycles, or at peak current is switched to finish charging the next capacitor in the series, which then dumps into the next coil, chasing the payload along.

    The energy is stored in these drive capacitors, distributed along the track.

    Mind, that’s only for the high speed part. You’d likely start out with drive wheels run by motors, until the speed got up too high for the wheels to be practical, then a section of drive coils fed 3 phase, and then finally the capacitor driven section.

    Because, of course, the power required to achieve 6 gs acceleration increases with the speed…

    Reply
  99. There’s also the case of certain orbital periods syncing such that they will never hit it, assuming no perturbation. But real world physics says the original poster is sorta right, eventually, plus all sats supersynchronous to GEO within the span of the upper tether length out to the counterweight as well. For long enough timespans.

    Reply
  100. There’s also the case of certain orbital periods syncing such that they will never hit it assuming no perturbation. But real world physics says the original poster is sorta right eventually plus all sats supersynchronous to GEO within the span of the upper tether length out to the counterweight as well. For long enough timespans.

    Reply
  101. I think this is doable and we will one day implement Arthur C. Clarke’s vision (or was it Tsiolkovsky?). In any case, it’s only about money. Jeff Bezos could probably fund this on his own. Isn’t it “just” about the right materials to handle the stresses? I also guess one can use maglev/electrostatic type tech so you won’t need moving parts. Seems like this is an engineering solution that can be built. Can it be commercialized? I dunno. Obviously there could be a market for hauling stuff up (and down) in space, including tourists. But why stop there? Why not build an elevator to the moon? It’s just a bit further away and it’s a great place to anchor the structure and bring moon habitats, mining, and other operations closer to Earth in a more reliable way. Possibly more cost efficient too.

    Reply
  102. I think this is doable and we will one day implement Arthur C. Clarke’s vision (or was it Tsiolkovsky?). In any case it’s only about money. Jeff Bezos could probably fund this on his own. Isn’t it just”” about the right materials to handle the stresses? I also guess one can use maglev/electrostatic type tech so you won’t need moving parts. Seems like this is an engineering solution that can be built. Can it be commercialized? I dunno. Obviously there could be a market for hauling stuff up (and down) in space”” including tourists. But why stop there? Why not build an elevator to the moon? It’s just a bit further away and it’s a great place to anchor the structure and bring moon habitats mining”” and other operations closer to Earth in a more reliable way. Possibly more cost efficient too.”””

    Reply
  103. I’ve always loved mass drivers. Ultimate in efficiency.

    … 70% of the things would be payload.
    … 10% to packaging.
    … 20% to circularizing rocketry.

    Solid rocket, most likely.

    It seemed like the perfect thing to install in someplace equatorial. Like, hmmm… oh, … Ecuador? Has mountains, too.

    (1.1) … d = ½at²
    (1.2) … v = at … t = v/a therefore
    (1.3) … d = v²/2a and by inversion solving for (a)
    (1.4) … a = v²/2d

    (2.1) … v is about 8,000 m/s
    (2.2) … d is 500 km
    (2.3) … a = 8,000² ÷ 2×500,000
    (2.4) … a = 64 m/s² (64 ÷ 9.81 → 6.5 Gs)

    Yep! We’re definitely on the same page. If the investment energy goes at least η=75% into the whole enchilada, then…

    (3.1) … E = mv²/2η
    (3.2) … E = 2500 × 8000² ÷ 2 × 0.75
    (3.3) … E = 107,000,000,000 joules
    (3.4) … E → 30,000 kWh … • $0.15 per kWh = $4,500 a launch in electricity.

    (4.1) … t = v/a = 8000 ÷ 64
    (4.2) … t → 125 sec or 2 minutes

    To lob 70% of 2500 kg or $2.57 per kg in electricity.
    However, like the Elon Musk analysis, there’s a lot of infrastructure to fund.
    Indefinitely.

    And the NOT insignificant problem of how to store a hundred billion joules and deliver it in a progressive power ramp in about 2 total minutes to the 500 km track. Its an interesting problem in its own right. You’d certainly want to have a 100 megawatt generator driving it, so as to be able to lob every 20 minutes or so, around the clock.

    Could deliver well over 126,000 kg to orbit a day from one well run mass thrower.
    That’s over 1 BFR’s worth or so, per day.

    GoatGuy

    Reply
  104. Will the return of investment be bad if Space Elevators are built WHEN carbon nanotubes are 100-1000 times cheaper than now, as well as BFR price to orbit gets as low as $80/kg?

    AND if we only build the Space Elevator once we have a thriving space economy in desperate need of haul mass transportation of products to and from Earth?

    Don´t imagine tiny elevators carrying people up and down.

    Imagine the elevator cars as vertical Emma Maersks, Barzans, Knock Nevis’, etc… a few of them going up and a few going down at the same time, at small speeds, getting 2-3 weeks to reach the other end of the cable, each one some 1 week ahead of the other.

    Reply
  105. Quite the superficial analysis, imho.

    I don´t think anybody disagrees space elevators are unfeasible now due to technology AND economics. From that, saying they may never be feasible?

    1 – Carbon nanotubes have been improving. We are able to produce better and more than 10 years ago. Where will we be in 10 years?

    2 – The lift tests are mostly based on transmitting power to the climbers. Through the use of lasers for example. However, carbon nanotubes are an awesome electricity transmitter. I won´t be surprised if in future, it’s the cables of the Space Elevators themselves transmitting power to the climbers.

    3 – The Van Allen belts are argument against HUMAN transportation AND/OR thin walled climber cars. I don´t see Space Elevators as being used to transport people, specially due to the long transit times

    4 – The argument about BFRs becoming cheap enough is soooooo poor. It’s like saying that cheap airplanes would end with ocean liners. The cheaper cost might mean they (or other rockets) will be the prefered method for humans to travelling to orbit. Where paying twice the price per kg of a space elevator is worth considering you get there much faster.

    Its an planes vs ships argument really. For moving millions of tons in space, you will want a system much CHEAPER. Specially if the material being moved is not that expensive. The cost of transport being more expensive than the material itself is a big no-no.

    It will prove unfeasible to launch 666 BFR flights to carry only 100 thousand tons into space. Each of those BFR flights having the explosive power of a small atomic bomb (like N1 rocket), doing LOTS of noise, having a risk of failure associated with each take-off and landing (like an airplane do).
    The price of the Space Elevator might fall due to BFR itself being able to carry 150 tons of carbon nanotube threads to space with each flight.

    And yet, it still won´t be worth to build the Space Elevator.

    It will be feasible WHEN we have a thriving space economy, where we need to constantly move big amounts of products between Earth and Space…

    Then we build space elevators for that purpose. While humans use rockets. And well, even cargo rockets will be used once in a while, just as cargo planes are also needed when you need to move some cargo fast instead of paying less for the transport.

    Reply
  106. Quite possible to build this, but make sure everyone on the project speaks Esperanto, uses a Dvorak keyboard, and everything is powered by fusion.

    Reply
  107. Quite possible to build this but make sure everyone on the project speaks Esperanto uses a Dvorak keyboard and everything is powered by fusion.

    Reply
  108. I think aside from the technical challenges, the thing that will kill it will be return on investment. Has anyone looked into EM catapult as a means to send tonnage to space? This is much more proven technology that could be built in the near future.

    Reply
  109. Wow, a lot of guys writing articles and commenting on articles that just like me cannot see the future beyond the singularity.

    Reply
  110. Wow a lot of guys writing articles and commenting on articles that just like me cannot see the future beyond the singularity.

    Reply
  111. In one of those ironic moments, I find myself disagreeing with both of your points, not significantly, but enough to write up a rebuttal. On (1), I would say “satellites, whether compact or big long cables, require active anti-collision micropositioning”. Consider … a potential satellite might be 100 meters (huge!, but with solar panels, possible) in size. Yet, in the scale of orbits, moving 100 meters out of the way with days to months of advance notice isn’t THAT much of an imposition. If the motion is “1 week out”, and 250 m is the safety margin, then that is ½ millimeter per second. NOT very fast. On (2), your point of micrometeorite abrasion is sound; yet the target is remarkably small in width. In length it is long. Doing quite a few calculus estimates, it can rather easily be shown that the cable if 1 cm by 1 dm on Earth (a fairly svelte cable) will be upwards of 8 m by 20 m at its thickest point (the geostationary point). Indeed, outside the atmosphere, it continues to thicken with distance… meaning that there is a LOT more cable in thickness to damage, and micrometeorites aren’t going to do as much damage. But more important than that is rebutting the idea that whizzing up and down the cable will wear it out. I think this is false: common hard chloroprene synthetic rubber wheels on aluminum or titanium hubs, clamping on both sides the cable, CLAMP the cable, not abrade it. Compared to the tension it would nominally be under, the compression is absolutely minor. Parts per thousand. Anyway, good hearing from you. Welcome to NBF. Come back soon! GoatGuy

    Reply
  112. In one of those ironic moments I find myself disagreeing with both of your points not significantly but enough to write up a rebuttal. On (1) I would say “satellites whether compact or big long cables require active anti-collision micropositioning”. Consider … a potential satellite might be 100 meters (huge! but with solar panels possible) in size. Yet in the scale of orbits moving 100 meters out of the way with days to months of advance notice isn’t THAT much of an imposition. If the motion is 1 week out””” and 250 m is the safety margin then that is ½ millimeter per second. NOT very fast. On (2) your point of micrometeorite abrasion is sound; yet the target is remarkably small in width. In length it is long. Doing quite a few calculus estimates it can rather easily be shown that the cable if 1 cm by 1 dm on Earth (a fairly svelte cable) will be upwards of 8 m by 20 m at its thickest point (the geostationary point). Indeed outside the atmosphere it continues to thicken with distance… meaning that there is a LOT more cable in thickness to damage and micrometeorites aren’t going to do as much damage. But more important than that is rebutting the idea that whizzing up and down the cable will wear it out. I think this is false: common hard chloroprene synthetic rubber wheels on aluminum or titanium hubs clamping on both sides the cable CLAMP the cable not abrade it. Compared to the tension it would nominally be under the compression is absolutely minor. Parts per thousand. Anyway”” good hearing from you.Welcome to NBF.Come back soon!GoatGuy”””””””

    Reply
  113. Rotavators seem a lot easier and realistic. They can be used in both directions and will gain momentum when deorbiting stuff. Should be possible to build a one-stage rocket that can dock with a rotavator. Perhaps something can be gained by staging rotavators too.

    Reply
  114. Agreed, we do not have the technology to build one around the Earth, but building one around the moon can be done today from a technical standpoint according to Isaac Arthur. He prefers a rotovator method for Earth. If you have never watched his Youtube series, for practical engineering and physics led futurism he is really hard to beat.

    Reply
  115. Biggest problem, after material strength, is that you spend so long going through the Van Allen belts.

    5-6 g acceleration, 500 km long mass driver in an evacuated tube ending at the top of a mountain, (Traditionally, it would be Pikes Peak.) with a really fast door at the top.

    No need to push material science, you emerge with enough speed to just need a circularizing burn at apogee. Throughput could be enormous.

    Reply
  116. More than the engineering challenge there is the financial challenge. The capital cost of a space elevator would required far more traffic than current traffic. The BFR is the better solution for now.

    Reply
  117. Its kind of interesting … working out the numbers from scratch, and seeing what their effect is on the overall cost of “doing a run”.

    Certainly — we can debate MY choices, but given:

    … LOX = $1.50/kg
    … LME = $2.06/kg
    … Fuel:Ox blend = $1.61/kg (from stochiometry)

    … STACK 1 ISP = 370
    … STACK 2 ISP = 430

    Working backward from stack № 2 to 1:

    № 2:
    … Payload = 100,000 kg, 25% of stack
    … Fuels = 280,000 kg, 70% stack
    … Structural = 20,000 kg, 5% stack

    № 1:
    … Payload = 400,000 kg, 15% stack
    … Fuels = 2,053,000 kg, 77% stack
    … Structural = 213,000 kg, 8% stack

    There are NO hard numbers as to the cost(s) of making first and second stages. Handwaving at best. But still its not hard to come up with defensible guesstimates.

    № 1:
    … cost per unit: $100,000,000
    … number of uses per: 25

    Per run:
    … cost recertify: 5% = $5,000,000
    … cost fuel: $3,309,000
    … cost ground sup: $1,000,000
    … cost spaceport: $500,000
    … cost insurance: $1,000,000
    … cost admin: $500,000
    … cost research: $5,000,000 (share of…)
    … cost crewing: $375,000
    … cost PROFIT: $25,000,000 (only 33% margin!)
    … cost mort/use: $4,007,000
    № 2:
    … cost per unit: $40,000,000
    … number of uses per: 10

    Per run:
    … cost recertify: 5% = $2,000,000
    … cost fuel: $450,000
    … cost ground sup: $250,000
    … cost spaceport: $0
    … cost insurance: $500,000
    … cost admin: $1,250,000
    … cost research: $5,000,000 (share of…)
    … cost crewing: $625,000
    … cost PROFIT: $10,000,000 (33% total margin)
    … cost mort/use: $3,998,000

    TOTAL:

    $69,000,000 per run cost
    $26.12 per kilogram (combined stacks, at takeoff)
    $700 per kg, of the 100,000 kg payload to orbit.

    Even when I make “number of uses” 999 for each, the cost only goes down to $620/kg. Simply, there’s a lot wrapped up in profit margin, ongoing research facility funding, and combined operational costs. The cost of fuel is insignificant.

    Just saying.
    Cherry cool-aid with vodka.
    GoatGuy

    Reply
  118. I think they’ve solved that particular issue with the Hoytether design that fails gracefully under “micro” meteor bombardment. Larger meteors could be an issue.

    However, even solving the technical issues, (And I don’t think graphene or carbon nanotubes are quite up to the challenge.) I don’t see how anything so vulnerable to attack, and so valuable, could endure in the face of modern terrorism. Space elevators are something a *peaceful* society might build, not ours.

    I think there are probably better high tech, non-rocket approaches to mass transit to orbit, such as a really large mass driver (200 km long through an evacuated tube ending at the top of a mountain.) that can be better secured.

    Reply
  119. Two major problems with a terrestrial space elevator: 1. Once built, the space elevator would immediately be on a collision course with every satellite below geostationary altitude. Active movement of the tether is required just to avoid a collision. 2. The ROI period for the elevator is limited by how quickly the elevator cars can ascend. The more quickly the cars ascend the sooner the tether will wear out. Also the space environment will subject the tether to micro-meteor impacts. It’s likely that complete replacement of the tether will be required before ROI is reached.

    Reply
  120. Two major problems with a terrestrial space elevator:1. Once built the space elevator would immediately be on a collision course with every satellite below geostationary altitude. Active movement of the tether is required just to avoid a collision.2. The ROI period for the elevator is limited by how quickly the elevator cars can ascend. The more quickly the cars ascend the sooner the tether will wear out. Also the space environment will subject the tether to micro-meteor impacts. It’s likely that complete replacement of the tether will be required before ROI is reached.

    Reply
  121. What’s he smoking? All boosters recovered Falcon Heavy cost is a little over $1,400/lb now. BFR will be at most $75/lb to LEO for the first 300 missions, which pays for R&D and infrastructure, after that it gets down to $25/lb.

    Reply
  122. What’s he smoking? All boosters recovered Falcon Heavy cost is a little over $1400/lb now.BFR will be at most $75/lb to LEO for the first 300 missions which pays for R&D and infrastructure after that it gets down to $25/lb.

    Reply
  123. You say there’s time enough to move the tether, but what about the energy required to move the mass of the whole ‘tang?

    If you’re trying to move the tether by pushing at the point along its’ length that an object would impact, then you’re pull up and down on the tether. You’d a need a pretty big tug to move that kind of mass. And that would also put a crap load of stress and strain on the material

    If you’re doing it by dragging the rock-at-the-top from side to side;
    again a purtty big tug. That would be a dance and a half!

    I suppose one way of not needing to move the top rock around all the time is to build in a bit of slack right from the git-go, then the right algorithm could allow for the tether to be set into motion with one big pluck, flopping around it’s axis, needing only occasional adjustments, as it dodges bullets.

    Bull-whip.

    I see three or four large pincers at the ends of long arms, extending down from the terminal, positioned around the tether, taking turns grabbing onto, pulling out and letting go, playing the tether like a one-string bass.

    Elevator music.

    It’s like when I’m out moving the sprinkler in the yard, I’ll give the hose a little flip to send a wave down the line, timed to reach just the right spot along its’ length at the right time so the hose doesn’t get caught on a rock.

    Except my hose isn’t 20,000 miles long, X times more massive than one elephant, nor in need of a never ending freestyle jam session, flawlessly played.

    Reply
  124. An Earth elevator is almost not possible – for technical, safety and political reasons.

    But its quite easy on the Moon and could be done on Mars. However, there is still a huge safety issue. Space elevators are super vulnerable against micrometeorits.

    Reply
  125. Comparing Space Elevators with Rockets is like comparing a railroad (or a canal system) with cars and trucks.
    Space Elevators are not cost effective when the cargo is small in size,mass, the total tonnage/year is small and the delivery is not continuous..
    They will become more interesting when the cargo moving up and down will increase and the needs for large payload will increase as well.
    A Space Elevator can be built large enough for every possible cargo (E.G. large like a oil tanker).

    The point about satellite debris are not very pertinent because bigger rockets, and the Space Elevator itself, will allow larger satellites to be deployed and maintained. reducing the need of many small satellites with a short life span.

    A satellite platform for telecommunication 10 m large (no solar panels included) could take the place of hundred small satellites easily.

    Reply
  126. There’s also the case of certain orbital periods syncing such that they will never hit it, assuming no perturbation. But real world physics says the original poster is sorta right, eventually, plus all sats supersynchronous to GEO within the span of the upper tether length out to the counterweight as well. For long enough timespans.

    Reply
  127. I think this is doable and we will one day implement Arthur C. Clarke’s vision (or was it Tsiolkovsky?). In any case, it’s only about money. Jeff Bezos could probably fund this on his own. Isn’t it “just” about the right materials to handle the stresses? I also guess one can use maglev/electrostatic type tech so you won’t need moving parts.

    Seems like this is an engineering solution that can be built. Can it be commercialized? I dunno. Obviously there could be a market for hauling stuff up (and down) in space, including tourists. But why stop there? Why not build an elevator to the moon? It’s just a bit further away and it’s a great place to anchor the structure and bring moon habitats, mining, and other operations closer to Earth in a more reliable way. Possibly more cost efficient too.

    Reply
  128. In one of those ironic moments, I find myself disagreeing with both of your points, not significantly, but enough to write up a rebuttal.

    On (1), I would say “satellites, whether compact or big long cables, require active anti-collision micropositioning”. Consider … a potential satellite might be 100 meters (huge!, but with solar panels, possible) in size. Yet, in the scale of orbits, moving 100 meters out of the way with days to months of advance notice isn’t THAT much of an imposition. If the motion is “1 week out”, and 250 m is the safety margin, then that is ½ millimeter per second. NOT very fast.

    On (2), your point of micrometeorite abrasion is sound; yet the target is remarkably small in width. In length it is long. Doing quite a few calculus estimates, it can rather easily be shown that the cable if 1 cm by 1 dm on Earth (a fairly svelte cable) will be upwards of 8 m by 20 m at its thickest point (the geostationary point). Indeed, outside the atmosphere, it continues to thicken with distance… meaning that there is a LOT more cable in thickness to damage, and micrometeorites aren’t going to do as much damage.

    But more important than that is rebutting the idea that whizzing up and down the cable will wear it out. I think this is false: common hard chloroprene synthetic rubber wheels on aluminum or titanium hubs, clamping on both sides the cable, CLAMP the cable, not abrade it. Compared to the tension it would nominally be under, the compression is absolutely minor. Parts per thousand.

    Anyway, good hearing from you.
    Welcome to NBF.
    Come back soon!

    GoatGuy

    Reply
  129. Two major problems with a terrestrial space elevator:

    1. Once built, the space elevator would immediately be on a collision course with every satellite below geostationary altitude. Active movement of the tether is required just to avoid a collision.

    2. The ROI period for the elevator is limited by how quickly the elevator cars can ascend. The more quickly the cars ascend the sooner the tether will wear out. Also the space environment will subject the tether to micro-meteor impacts. It’s likely that complete replacement of the tether will be required before ROI is reached.

    Reply
  130. What’s he smoking? All boosters recovered Falcon Heavy cost is a little over $1,400/lb now.

    BFR will be at most $75/lb to LEO for the first 300 missions, which pays for R&D and infrastructure, after that it gets down to $25/lb.

    Reply
  131. It’s not the same at all . Mzso is right, a rail gun (using magnetics) could launch something into space (theoretically), but a mechanical catapult system has serious limitations. There’s a reason why catapults fell out of favor by the 1700’s. Even modern catapults (see the annual punkin chunkin contest) lose out to compressed air cannons. Not sure how an elevator relates to a catapult, you must be thinking of something else.

    Reply
  132. It’s not the same at all . Mzso is right a rail gun (using magnetics) could launch something into space (theoretically) but a mechanical catapult system has serious limitations. There’s a reason why catapults fell out of favor by the 1700’s. Even modern catapults (see the annual punkin chunkin contest) lose out to compressed air cannons. Not sure how an elevator relates to a catapult you must be thinking of something else.

    Reply

Leave a Comment