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From someone who knows little about this -- what is the advantage of this kind of engine? And have we scrapped the idea of space elevators?

patrickwalton 5y ago
Beyond all the theoretical implementation complexities of space elevators, we don't even know of a single material with the required tensile strength. Graphene was thought to be strong enough, but recent research found practical graphene had defects that significantly reduces its strength below that required for a space elevator. Space elevators aren't scrapped, just on the shelf until we even have a material that let's us think they might be feasible. That said, Lunar space elevators could be done with lower-strength materials, like Kevlar, and there are some people working on them. For Earth orbit, I think the centrifuge concept (e.g. SpinLaunch) has some promise. Still some huge implementation hurdles, but could be a huge step forward to put all of the energy for the first stage on the ground.
- wombatpm 5y ago
  Spin Launch for cargo. Can’t imagine being a passenger
  - qayxc 5y ago
    At about 10,000Gs of acceleration (as per their claims¹ ~2200m/s in a 100m vacuum chamber, e.g. a=v²/r ≈ 97,000m/s² or roughly 10,000Gs) any human passenger would be liquified and form a nice smooth film on the inner surfaces of the vehicle. ¹https://www.spinlaunch.com/orbital#p2 https://www.spinlaunch.com/orbital#p2
  - panick21_ 5y ago
    How many SpinLaunch to launch the same amount of Cargo compared to a single Starship. With a 100m arm, the will launch only like a few 100kg, a single Starship can launch 150tons. Why in the world would anybody use spin launch?
- moron4hire 5y ago
  SpinLaunch is easily the dumbest thing I've seen this year, and I got to become aware of NFTs this year. It's going to end up in the long list of grifts designed to bleed investors.
  - spanktheuser 5y ago
    Curious about your reasoning. I immediately wondered what type of cargo would be suitable for this sort of launch system. I came up with a fairly short list. Fuel/water/perhaps food for interplanetary spacecraft destined for Luna or Mars. I imagine one could design some types of cubesats to withstand the tremendous acceleration forces. That was about it. Is your skepticism based on cargo suitability or other factors.
    - NikolaeVarius 5y ago
      Who the fuck cares about cargo before trying to figure out if any second stage rocket that isn't a rock can reasonably survive the extended application of high G-forces
      - robszumski 5y ago
        They have some data that indicates most off the shelf electronics survive or need very minor modifications to withstand the G forces. That's better than no data at all but they do have a ways to go.
        mayama 5y ago
        It's not just g forces. It's combination of g forces and atmosphere drag. Drag forces during launch could be bigger issue.
    - avmich 5y ago
      Some classification considers 3 types of cargo - bulk materials (metals, fuel); complex electronics; humans. The majority of weight is in the 1st type. Unless first two types have complex mechanical structure, where loads can't be distributed into supports - which is an important issue - the first two groups are candidates.
- Ajedi32 5y ago
  Spinlaunch is potentially okay for cargo, assuming they can overcome limitations imposed by atmospheric drag, and scale up sufficiently to make it practical; but the G forces involved make it impossible to use for human spaceflight. IMO the closest thing to a space elevator realistically achievable with today's technology would be a Skyhoook: https://en.wikipedia.org/wiki/Skyhook_(structure) https://en.wikipedia.org/wiki/Skyhook_(structure)
  - jhgb 5y ago
    Is something like spinlaunch (centrifugal force) even better than a hydrogen gun (linear acceleration) from the perspective of g forces? For example Quicklaunch (6 km/s speed, 1100 m barrel) would require ~1700g of acceleration. Spinlaunch appears to be significantly more demanding while providing even smaller initial velocity. Even if it's just cargo applications, surely there's still a difference between 1000g and 10000g.
    - Ajedi32 5y ago
      The main advantages of spin launch's approach over a more conventional mass driver are that it takes up less space (Quicklaunch's proposed driver is over 1km long), and that it requires less peak power to get up to speed (Spinlaunch accelerates over a period of one and half hours).
      - jhgb 5y ago
        One could argue that Quicklaunch doesn't practically require much peak power either since you have means to store hydrogen and oxygen in tanks over time if you generate them in trickles. The fact that firing it generates high peak power is no more relevant for practicality than the fact that firing a handgun generates high peak power. It's just combustion. As for size, honestly, that doesn't seem to be much of a problem. You still have exclusion zones, and I'd argue that the exclusion zone around a spinning device like Spinlaunch proposes would have to be fairly large in all directions. Quicklaunch doesn't have a failure mode where the payload goes sideways at its full speed. Even if Quicklaunch were on land (which it wasn't planned to be), it would still probably require a smaller exclusion area.
- jjk166 5y ago
  Space elevators don't work on the moon. While gravity is weaker, the moon's rotation period is also much lower. To build a space elevator, its center of mass must be in a stationary orbit over the body. A geostationary orbit around the moon (selenostationary) would be about 88,000 km. The moon's Hill sphere, the region where its gravity dominates and thus things can stay in stable orbit around it, is only about 58,000 km. Basically a lunar space elevator would be so tall that Earth's gravity would yoink it off the moon. You could potentially build a skyhook on the moon, which a space elevator is merely a special case of, but you lose a lot of the advantages of a space elevator - namely you still need something to blast off the surface to reach the skyhook, and you have to carefully time it because everything's moving at extremely high speed. Saves a lot of fuel though.
  - Valgrim 5y ago
    On the moon, you'd need a mass driver in conjunction with a skyhook.
    - jhgb 5y ago
      But why not just build a mass driver, then? It's a somewhat large horizontal structure, compared to a space elevator which is an absolutely humongous vertical structure. If you can reach 2 km/s on magnetic rails, you don't need anything else to launch from the Moon -- or even land on it.
      - Valgrim 5y ago
        Because unless you reach escape velocity, you still need to adjust your trajectory to insert into orbit, or else you're just going to crash back on the surface. If you use a rocket that's fine you just point in a different direction and burn, but if you're trying to launch, say, a few trillion tons of stuff, you need something a tad more efficient
        jhgb 5y ago
        It's not like you need no maneuvering when you use a space elevator. At some point you have to detach from it. You'll always need course corrections afterwards.
- panick21_ 5y ago
  SpinLaunch is a terrible idea. You need to build a non reusable rocket upper stage for every couple 100kg or material you want to launch. Starship fully reusable will end up with 150t per launch. How many spin launches do you need to get the same cargo as a single Starship launch. 300 Upper-stages you need to build and launch or launch literally one Starship. Good luck with your competition. Almost all of those alternative launch things make almost no sense once you make fully reusable rockets work.
the_cramer 5y ago
We haven't. We just can't produce enough carbon nanotubes cheaply to build a space elevator. Amongst other technical issues. One limiting factor of a rocket engine is the exhaust cone. This big dome-shaped piece of internally cooled structure tries to make the burning of fuel most efficient by controlling the shape of the exhaust reaction. In atmosphere you need a different size than in orbit to burn optimal, that's one reason why staging is done and the second stage is much different in cone size. Since in aerospike the direction and shape of the exhaust gasses is different, air pressure is used as a "dynamic cone" making single-stage to orbit" rockets much more feasable. I'm not sure if we want that at all, though.
Tuna-Fish 5y ago
Space elevators are still pretty far out there. And if we ever do end up building one, we're going to need pretty damn good rockets to do that. To reach maximum theoretical performance, a rocket engine nozzle needs to expand the exhaust to be of equal pressure as the ambient air. Being too underexpanded can actually destroy the engine, and even well before that being over- or underexpanded saps efficiency, so you can improve performance by specializing for the pressure you target. But of course, as a rocket ascends, pressure falls. This means that the expansion ratios of traditional engines are compromises over the pressure range they are expected to operate in. Aerospike engines use a neat hack to make a "virtual nozzle", where the pressure of outside air is used to push on the exhaust stream. This makes it slightly less efficient than a traditional de Laval nozzle that is specialized for the exact pressure, but it can maintain that not-perfect but high level of efficiency for the whole ascent, from atmospheric to vacuum. When everyone was trying to build single stage to orbit vehicles, aerospikes sounded very promising as they would allow a single engine to be used from the launch pad to vacuum with reasonable efficiency. However, now that first stages are routinely returning to the launch site and landing on their own, SSTOs are not nearly as attractive, and with a two-stage architecture, you want to give the second stage a proper vacuum engine, and then the first stage won't lose that much if it's optimized for near-sealevel conditions. I'm not sure aerospikes make that much sense anymore.
klodolph 5y ago
> From someone who knows little about this -- what is the advantage of this kind of engine? Take a traditional bell nozzle engine. The shape of the bell is designed to redirect the exhaust in the correct direction, but one of the design parameters for the shape is the ambient air pressure. If you design it to work at a specific altitude, it will be less efficient at other altitudes. The aerospike is more efficient over a broader range of altitudes. (That is, if you take the average efficiency over a wider range of altitudes, the aerospike wins. If you pick one altitude or a narrow range of altitudes, the traditional nozzle wins.)
- reasonabl_human 5y ago
  Piggy backing off of this- the real net benefit is unblocking an SSTO design (Single Stage to Orbit). Instead of having a lift stage and an orbital stage, aerospikes can theoretically do both, meaning one cohesive vehicle from launch through orbit. The weight savings and reusability factors are huge if SSTO setups become feasible.
  - moonbug 5y ago
    Fine, except the era of expendable launch vehicles is already drawing to a close.
- ashtonkem 5y ago
  Piggybacking off this too, if you look at rocket specifications, they’ll often mention the same motor on different stages with a (VAC) behind it. This denotes the different bell shape required to make the motor efficient in vacuum as compared to sea level. The issue with an aero spike is that the benefits just aren’t there for a multi stage rocket. We do multi stage rockets to balance the needs of high thrust at the launch pad with the need to minimize our final non-payload weight in orbit. Varying the bell design to match flight profile naturally plays well with this approach. If you’re going to ditch parts of your rocket for weight saving during ascent, you might as well tune each stage for the altitude it will actually work at. Motors that need to work at all altitudes are pretty rare, the only ones I can think of are SSTOs in theory, and the space shuttle main engines. If we could get a falcon 9 with aero spikes it would theoretically be an improvement, but not a huge one. All the gains would be in the edges of various stages where say, the stage 1 motors are flying above their designed altitude. The efficiency gains are there, but they might be completely offset by increased weight, cost, cooling concerns, etc.
avmich 5y ago
The space elevators problems include not only finding a good cable material, but also solving the problem of collision with satellites, so I'm not holding my breath. Aerospike nozzles are spike nozzles where the spike is cut short and "replaced by air". They are shorter and usually lighter than equivalent bell-shaped nozzles, but they have bigger surface area in the critical section - most heat-loaded part of the engine - so cooling them is harder. For small engines the problem is cooling, and for big engines there is a problem of area where to put those engines (for large rockets length and weight of nozzle isn't a problem, but cross-section of the rocket, where the engines have to be installed, is), so aerospikes have different trade-off than bell-shaped nozzles.
oconnor663 5y ago
My naive understanding: The appeal of a space elevator is that all you need to get to space is the energy to climb the elevator. But if Starship is able to hit its "fully and rapidly reusable" goals, it will have basically achieved the same thing: You can go to space on Starship for not much more than the cost of fuel to get there. The next question is which version is more energy efficient. Again, my very naive understanding is that they seem to be kind of similar. The space elevator is less efficient than you might think, because you can't just run electrical wires up and down it. The weight would be a problem, and resistance losses over such a long cable would be high. Instead, you might send power through the air with a big laser, but that also comes with efficiency losses, in the same ballpark as rocket engines. And of course, Starship has the obvious advantage that it seems like it actually might work with current technology. I think this comparison is an interesting way to highlight what a big deal it will be, if Starship does work.
- mercutio2 5y ago
  I agree that space elevators are very unlikely in the next few centuries. But arguing that Starship achieves basically the same thing seems wrong to me. Starship is subject to the rocket equation. That means all but a few percent of its launch mass is rocket fuel. Space hooks of all sorts require some transfer of energy, but the idea is it's on the order of magnitude of the actual potential energy gained. Edit: It strikes me as implausible that we'll get unobtainium with sufficient material strength to build a space elevator without accompanying superconductors run through the elevator structure, but when I ran the numbers, current lithium ion batteries are about 1/60th of the energy density of mass moved from the highest equatorial point on earth to geosync orbit. Not so very different from the rocket equation, you're right, if we decide there's no way to convey energy through the space elevator. It's all sci-fi anyway!
  - perl4ever 5y ago
    How about an electric rail gun in a tunnel up a mountain? Has Musk ever said that's what the Boring company is going to do some day?
zardo 5y ago
> And have we scrapped the idea of space elevators? If you're looking at sci-fi fixed infrastructure for access to space, the orbital ring looks more plausible. It's out there, but unlike a space elevator it doesn't require gigatons of unobtanium cable.

patrickwalton 5y ago

Beyond all the theoretical implementation complexities of space elevators, we don't even know of a single material with the required tensile strength. Graphene was thought to be strong enough, but recent research found practical graphene had defects that significantly reduces its strength below that required for a space elevator. Space elevators aren't scrapped, just on the shelf until we even have a material that let's us think they might be feasible. That said, Lunar space elevators could be done with lower-strength materials, like Kevlar, and there are some people working on them. For Earth orbit, I think the centrifuge concept (e.g. SpinLaunch) has some promise. Still some huge implementation hurdles, but could be a huge step forward to put all of the energy for the first stage on the ground.

wombatpm 5y ago
Spin Launch for cargo. Can’t imagine being a passenger
- qayxc 5y ago
  At about 10,000Gs of acceleration (as per their claims¹ ~2200m/s in a 100m vacuum chamber, e.g. a=v²/r ≈ 97,000m/s² or roughly 10,000Gs) any human passenger would be liquified and form a nice smooth film on the inner surfaces of the vehicle. ¹https://www.spinlaunch.com/orbital#p2 https://www.spinlaunch.com/orbital#p2
- panick21_ 5y ago
  How many SpinLaunch to launch the same amount of Cargo compared to a single Starship. With a 100m arm, the will launch only like a few 100kg, a single Starship can launch 150tons. Why in the world would anybody use spin launch?
moron4hire 5y ago
SpinLaunch is easily the dumbest thing I've seen this year, and I got to become aware of NFTs this year. It's going to end up in the long list of grifts designed to bleed investors.
- spanktheuser 5y ago
  Curious about your reasoning. I immediately wondered what type of cargo would be suitable for this sort of launch system. I came up with a fairly short list. Fuel/water/perhaps food for interplanetary spacecraft destined for Luna or Mars. I imagine one could design some types of cubesats to withstand the tremendous acceleration forces. That was about it. Is your skepticism based on cargo suitability or other factors.
  - NikolaeVarius 5y ago
    Who the fuck cares about cargo before trying to figure out if any second stage rocket that isn't a rock can reasonably survive the extended application of high G-forces
    - robszumski 5y ago
      They have some data that indicates most off the shelf electronics survive or need very minor modifications to withstand the G forces. That's better than no data at all but they do have a ways to go.
      - mayama 5y ago
        It's not just g forces. It's combination of g forces and atmosphere drag. Drag forces during launch could be bigger issue.
  - avmich 5y ago
    Some classification considers 3 types of cargo - bulk materials (metals, fuel); complex electronics; humans. The majority of weight is in the 1st type. Unless first two types have complex mechanical structure, where loads can't be distributed into supports - which is an important issue - the first two groups are candidates.
Ajedi32 5y ago
Spinlaunch is potentially okay for cargo, assuming they can overcome limitations imposed by atmospheric drag, and scale up sufficiently to make it practical; but the G forces involved make it impossible to use for human spaceflight. IMO the closest thing to a space elevator realistically achievable with today's technology would be a Skyhoook: https://en.wikipedia.org/wiki/Skyhook_(structure) https://en.wikipedia.org/wiki/Skyhook_(structure)
- jhgb 5y ago
  Is something like spinlaunch (centrifugal force) even better than a hydrogen gun (linear acceleration) from the perspective of g forces? For example Quicklaunch (6 km/s speed, 1100 m barrel) would require ~1700g of acceleration. Spinlaunch appears to be significantly more demanding while providing even smaller initial velocity. Even if it's just cargo applications, surely there's still a difference between 1000g and 10000g.
  - Ajedi32 5y ago
    The main advantages of spin launch's approach over a more conventional mass driver are that it takes up less space (Quicklaunch's proposed driver is over 1km long), and that it requires less peak power to get up to speed (Spinlaunch accelerates over a period of one and half hours).
    - jhgb 5y ago
      One could argue that Quicklaunch doesn't practically require much peak power either since you have means to store hydrogen and oxygen in tanks over time if you generate them in trickles. The fact that firing it generates high peak power is no more relevant for practicality than the fact that firing a handgun generates high peak power. It's just combustion. As for size, honestly, that doesn't seem to be much of a problem. You still have exclusion zones, and I'd argue that the exclusion zone around a spinning device like Spinlaunch proposes would have to be fairly large in all directions. Quicklaunch doesn't have a failure mode where the payload goes sideways at its full speed. Even if Quicklaunch were on land (which it wasn't planned to be), it would still probably require a smaller exclusion area.
jjk166 5y ago
Space elevators don't work on the moon. While gravity is weaker, the moon's rotation period is also much lower. To build a space elevator, its center of mass must be in a stationary orbit over the body. A geostationary orbit around the moon (selenostationary) would be about 88,000 km. The moon's Hill sphere, the region where its gravity dominates and thus things can stay in stable orbit around it, is only about 58,000 km. Basically a lunar space elevator would be so tall that Earth's gravity would yoink it off the moon. You could potentially build a skyhook on the moon, which a space elevator is merely a special case of, but you lose a lot of the advantages of a space elevator - namely you still need something to blast off the surface to reach the skyhook, and you have to carefully time it because everything's moving at extremely high speed. Saves a lot of fuel though.
- Valgrim 5y ago
  On the moon, you'd need a mass driver in conjunction with a skyhook.
  - jhgb 5y ago
    But why not just build a mass driver, then? It's a somewhat large horizontal structure, compared to a space elevator which is an absolutely humongous vertical structure. If you can reach 2 km/s on magnetic rails, you don't need anything else to launch from the Moon -- or even land on it.
    - Valgrim 5y ago
      Because unless you reach escape velocity, you still need to adjust your trajectory to insert into orbit, or else you're just going to crash back on the surface. If you use a rocket that's fine you just point in a different direction and burn, but if you're trying to launch, say, a few trillion tons of stuff, you need something a tad more efficient
      - jhgb 5y ago
        It's not like you need no maneuvering when you use a space elevator. At some point you have to detach from it. You'll always need course corrections afterwards.
panick21_ 5y ago
SpinLaunch is a terrible idea. You need to build a non reusable rocket upper stage for every couple 100kg or material you want to launch. Starship fully reusable will end up with 150t per launch. How many spin launches do you need to get the same cargo as a single Starship launch. 300 Upper-stages you need to build and launch or launch literally one Starship. Good luck with your competition. Almost all of those alternative launch things make almost no sense once you make fully reusable rockets work.

the_cramer 5y ago

We haven't. We just can't produce enough carbon nanotubes cheaply to build a space elevator. Amongst other technical issues. One limiting factor of a rocket engine is the exhaust cone. This big dome-shaped piece of internally cooled structure tries to make the burning of fuel most efficient by controlling the shape of the exhaust reaction. In atmosphere you need a different size than in orbit to burn optimal, that's one reason why staging is done and the second stage is much different in cone size. Since in aerospike the direction and shape of the exhaust gasses is different, air pressure is used as a "dynamic cone" making single-stage to orbit" rockets much more feasable. I'm not sure if we want that at all, though.

Tuna-Fish 5y ago

Space elevators are still pretty far out there. And if we ever do end up building one, we're going to need pretty damn good rockets to do that. To reach maximum theoretical performance, a rocket engine nozzle needs to expand the exhaust to be of equal pressure as the ambient air. Being too underexpanded can actually destroy the engine, and even well before that being over- or underexpanded saps efficiency, so you can improve performance by specializing for the pressure you target. But of course, as a rocket ascends, pressure falls. This means that the expansion ratios of traditional engines are compromises over the pressure range they are expected to operate in. Aerospike engines use a neat hack to make a "virtual nozzle", where the pressure of outside air is used to push on the exhaust stream. This makes it slightly less efficient than a traditional de Laval nozzle that is specialized for the exact pressure, but it can maintain that not-perfect but high level of efficiency for the whole ascent, from atmospheric to vacuum. When everyone was trying to build single stage to orbit vehicles, aerospikes sounded very promising as they would allow a single engine to be used from the launch pad to vacuum with reasonable efficiency. However, now that first stages are routinely returning to the launch site and landing on their own, SSTOs are not nearly as attractive, and with a two-stage architecture, you want to give the second stage a proper vacuum engine, and then the first stage won't lose that much if it's optimized for near-sealevel conditions. I'm not sure aerospikes make that much sense anymore.

klodolph 5y ago

> From someone who knows little about this -- what is the advantage of this kind of engine? Take a traditional bell nozzle engine. The shape of the bell is designed to redirect the exhaust in the correct direction, but one of the design parameters for the shape is the ambient air pressure. If you design it to work at a specific altitude, it will be less efficient at other altitudes. The aerospike is more efficient over a broader range of altitudes. (That is, if you take the average efficiency over a wider range of altitudes, the aerospike wins. If you pick one altitude or a narrow range of altitudes, the traditional nozzle wins.)

reasonabl_human 5y ago
Piggy backing off of this- the real net benefit is unblocking an SSTO design (Single Stage to Orbit). Instead of having a lift stage and an orbital stage, aerospikes can theoretically do both, meaning one cohesive vehicle from launch through orbit. The weight savings and reusability factors are huge if SSTO setups become feasible.
- moonbug 5y ago
  Fine, except the era of expendable launch vehicles is already drawing to a close.
ashtonkem 5y ago
Piggybacking off this too, if you look at rocket specifications, they’ll often mention the same motor on different stages with a (VAC) behind it. This denotes the different bell shape required to make the motor efficient in vacuum as compared to sea level. The issue with an aero spike is that the benefits just aren’t there for a multi stage rocket. We do multi stage rockets to balance the needs of high thrust at the launch pad with the need to minimize our final non-payload weight in orbit. Varying the bell design to match flight profile naturally plays well with this approach. If you’re going to ditch parts of your rocket for weight saving during ascent, you might as well tune each stage for the altitude it will actually work at. Motors that need to work at all altitudes are pretty rare, the only ones I can think of are SSTOs in theory, and the space shuttle main engines. If we could get a falcon 9 with aero spikes it would theoretically be an improvement, but not a huge one. All the gains would be in the edges of various stages where say, the stage 1 motors are flying above their designed altitude. The efficiency gains are there, but they might be completely offset by increased weight, cost, cooling concerns, etc.

avmich 5y ago

The space elevators problems include not only finding a good cable material, but also solving the problem of collision with satellites, so I'm not holding my breath. Aerospike nozzles are spike nozzles where the spike is cut short and "replaced by air". They are shorter and usually lighter than equivalent bell-shaped nozzles, but they have bigger surface area in the critical section - most heat-loaded part of the engine - so cooling them is harder. For small engines the problem is cooling, and for big engines there is a problem of area where to put those engines (for large rockets length and weight of nozzle isn't a problem, but cross-section of the rocket, where the engines have to be installed, is), so aerospikes have different trade-off than bell-shaped nozzles.

oconnor663 5y ago

My naive understanding: The appeal of a space elevator is that all you need to get to space is the energy to climb the elevator. But if Starship is able to hit its "fully and rapidly reusable" goals, it will have basically achieved the same thing: You can go to space on Starship for not much more than the cost of fuel to get there. The next question is which version is more energy efficient. Again, my very naive understanding is that they seem to be kind of similar. The space elevator is less efficient than you might think, because you can't just run electrical wires up and down it. The weight would be a problem, and resistance losses over such a long cable would be high. Instead, you might send power through the air with a big laser, but that also comes with efficiency losses, in the same ballpark as rocket engines. And of course, Starship has the obvious advantage that it seems like it actually might work with current technology. I think this comparison is an interesting way to highlight what a big deal it will be, if Starship does work.

mercutio2 5y ago
I agree that space elevators are very unlikely in the next few centuries. But arguing that Starship achieves basically the same thing seems wrong to me. Starship is subject to the rocket equation. That means all but a few percent of its launch mass is rocket fuel. Space hooks of all sorts require some transfer of energy, but the idea is it's on the order of magnitude of the actual potential energy gained. Edit: It strikes me as implausible that we'll get unobtainium with sufficient material strength to build a space elevator without accompanying superconductors run through the elevator structure, but when I ran the numbers, current lithium ion batteries are about 1/60th of the energy density of mass moved from the highest equatorial point on earth to geosync orbit. Not so very different from the rocket equation, you're right, if we decide there's no way to convey energy through the space elevator. It's all sci-fi anyway!
- perl4ever 5y ago
  How about an electric rail gun in a tunnel up a mountain? Has Musk ever said that's what the Boring company is going to do some day?

zardo 5y ago

> And have we scrapped the idea of space elevators? If you're looking at sci-fi fixed infrastructure for access to space, the orbital ring looks more plausible. It's out there, but unlike a space elevator it doesn't require gigatons of unobtanium cable.