The fastest growing plant (according to the Google) is a species of bamboo that can grow 91cm/day. At that rate, it would take about 8.25 years to grow the Golden Gate Bridge (2737.4m). It’s probably still faster to hire a construction company, but that’s not bad. And breeding faster-growing plants is probably a lot easier than inventing nanoscale machines.
How do you suppose that those tiny cubes attach to each other? You’re never going to be able to get enough strength for a bridge that way.
And bamboo does grow very fast, and it is actually a pretty useful material from an engineering standpoint (largely because of its low weight), but it probably wouldn’t be the right material for a bridge or other structure of similar scale.
They could mechanically interlock, like 3D puzzle pieces, using a rotating or sliding mechanism to change states. Clearly they would never be as strong (volumetrically) as the raw material, since only part of the inside will be load-bearing, but it seems that the 25-50% range would be doable. Probably good enough for a bridge, especially if the robots are made from stronger materials (diamondoid) than typical bulk materials (steel, concrete).
Yep. You could also use the cubes for the parts of the bridge under compression, and use conventional steel cables for the parts under tension. I think solid cubes full of robot parts would be reasonably resistant to compression.
I haven’t read all of it, but would these nanomachines be used for people?
For the OP:
A space Elevator is probably not going to be use because of certain challenges like, if this is for the moon, what are suppose to do with it moving all the time.
We already have railguns that work. I don’t know so much about batteries.
When it comes to elements, people are still trying to find a way to stabilize the unun elements we created in labs, which I believe are highly radioactive. I have this link that talks about it: Synthetic element - Wikipedia
Beg pardon? Of course it’s moving all the time. It’d fall otherwise. And you can use it to get anywhere you like, not just the Moon.
No. Well, not directly, at least. This level of technology would make destructive imaging of brains pretty easy. (it’s already marginally doable today with multiple beam electron microscopes)
With nanoscale parts, you could build a machine that destructively scanned brains down to atomic levels of detail.
Destructive scanning means you put a person to sleep, preserve their brain using a method that preserves all the details, slice the brain into many thin slices, and then scan them. A detailed enough model would allow you to build a computer emulation of the original brain.
A messy way to do it, but it is a workable solution for biological death and disease. Just have to “die” once, and you’re de facto immortal. (since once you have a data file that represents the neural state of a person, it is straightforward to copy that file enough times to make the probability of losing all copies essentially zero)
What I meant was the moon orbits around the planet so it wouldn’t be used to connect to the moon that much for it unless we get more space elevators. From additional research, a space elevator would have some problems with vibrations, weather, Meteoroids and micrometeorites, Corrosion, Satellites, violent humans, Radiation and resulting ionization. as seen from this article: http://io9.com/5984371/why-well-probably-never-build-a-space-elevator
It does say that it would work on the moon.
A lunar space elevator would not go between the earth and the moon. It would go between the lunar surface and geosynchronous orbit for Luna itself. The reason such a device is interesting is because you could build the elevator cable out of ordinary kevlar.
There’s little reason to think an elevator like that would ever be practical : if you really needed the capability to lift loads from the lunar surface for industrial purposes, you would get better capacity for the same resource investment with one of these : http://www.askmar.com/Massdrivers/Superconducting%20Quenchgun.pdf
At least, I’m fairly certain this is the case. An elevator is a massive cable, and you can only have as many climbers as the capable structure itself can support, and you have to wait for the climbers to reach the top (a process that takes days) before you can launch more.
With a superconducting quench gun, you can launch a payload as often as once a minute or so, given a sufficient power plant. The payload remains in the barrel for only a fraction of a second.
Nor would an Earthly space elevator physically reach anywhere near as far as the Moon. It’d only go a bit above geosynchronous height. You could still use it to get to the Moon, but that’d be by climbing the cable up to near the top and then letting go to fall the rest of the way up.
And hear I thought it would be for the moon because of a misconception. My bad.
Actually, I’ve long thought that the materials science part of constructing a space elevator would be the easy part. The more difficult challenge would be political.
First off, you’d have to carefully manage satellite orbits so they don’t impact the cable. Getting all the counties and private corporations with satellites in orbit to agree to one set of rules will be a massive headache.
Then there’s the risk management. A cable thick enough to support passenger traffic is probably going to mass millions of tons, and be long enough to wrap around the earth several times. What happens if it fails? The catastrophic energy released by a falling cable would compare to a nuclear war. And the risk would be borne disproportionately by equatorial countries, just to make the argument more entertaining. Even if the risk can be mathematically proved to be negligible, there will still be legions of nutjobs who refuse to believe the numbers.
And there will surely be other arguments. Who gets the economic boost of living next to the downside end? How do you placate the folks who will object to funding this pie in the sky pipedream when we have so many poor starving innocents here on earth who need help? This will likely be the most expensive public works project in human history, who gets oversight on the accounting to see the budget doesn’t get siphoned off in graft and corruption?
Perhaps the real unobtanium here is the consensus, cooperation and common sense to make to make such a massive project work.
I’d say the unobtanium here is the group of engineers who would choose an elevator over the alternatives. There are several good alternatives that are probably cheaper per launch than an elevator. An elevator isn’t free, it’s a 28,000 mile long cable that has a finite lifespan and is constantly under enormous stress. You can only have a limited number of climbers on the cable at a time (the climbers are additional load). This in turn means there’s a maximum capacity here : pay some incredible sum to install a cable, and only get another launch every few days.
An electromagnetic launcher doesn’t have this limit. You can do another launch about every minute (assuming you can supply the energy and have the payloads lined up). That means for a comparable up front investment, you’re getting thousands of times more payload to orbit.
Laser launch doesn’t have this limit, and it’s human ratable. With ablative laser propulsion, you can do a launch immediately after the last one finishes circularizing - or about every 15 minutes.
Oh, laser launch and electromagnetic launchers are distributed systems. If a laser module or magnet fails, the rest of the launcher is intact and probably capable of still launch spacecraft. If any component of the elevator cable fails anywhere, you lose the entire elevator.
There’s also a huge risk of deliberate attack here. It’s a rather large target, impossible to defend, and only needs a single strike to disable. An anti satellite missile would shred the elevator cable.
A space elevator requires significant up-front investment, true, but you can make the per-launch cost arbitrarily low. Laser launchers still require the input of enormous amounts of energy, but one can operate an elevator like a siphon, with almost all of the energy provided by the Earth’s rotation (and even that you can keep in balance, so long as you bring down an equal mass to what you send up-- picture a trade between Earth and Mars of seawater for iron ore, for instance).
Energy isn’t really the big cost, though, as long as you can generate it on Earth (i.e., you don’t carry the fuel with you and you can use large, efficient plants). 1 kg in LEO requires ~9.5 kW-h of energy. That’s under $0.50 at industrial rates.
Whether energy is a significant cost or not depends on how efficiently it’s applied. Rockets, as we both know, are phenomenally inefficient, and so their energy costs make them expensive. Laser launchers are more efficient than rockets, since the energy supply can remain on the surface, but still, “more efficient than rockets” is damning with faint praise.
Right; I’m assuming an EM launch system is the alternative system here, and one can clearly make that arbitrarily close to “perfect” efficiency (ignoring the circularization rocket). Laser launch still needs propellant, which means it still obeys the rocket equation.
One could do a human-ratable EM system–it’s probably still easier than a space elevator. It would be over 100 km long, and only work for healthy, young humans, but it’s doable.
An EM launch system, such as a coilgun, still has to punch through the atmosphere at high speed. One could in principle make the projectile an extremely aerodynamic shape, but there are practical limits on that. And if you’re making it long enough to be man-rated, it’s going to have to be almost horizontal, which means it’s going to have to punch through much more atmosphere than a conventional rocket. An elevator, by contrast, can run arbitrarily slowly (and straight up), and so make the atmospheric drag arbitrarily small.
Though I’ll grant that a coilgun could be practical on an airless world such as the Moon. Whether it’s more practical than a skyhook there, I don’t know, and would depend on just how expensive nanofiber is at the time you’re building it, where the nanofiber is produced, where the raw materials come from, and what infrastructure you have for moving the materials around.
Chronos : you’re ignoring the capacity utilization side of it. If you build an EM launcher, you can fire it essentially all the time - there’s no contact friction with a superconducting quench gun. You also have spare magnets so if one is offline you can keep launching.
Yes, you have to pay the marginal cost of electricity power with each launch. And, realistically maybe it’s only 50% efficient, factoring in losses in the launcher and atmospheric friction. That’s only $1 a kg for the electricity.
With an elevator, you have to pay a much larger marginal cost of elevator maintenance and the capital debt servicing. (or return on investment, either way)
This is because you’re only able to do a launch once every day or 2, instead of ~once a minute (theoretical maximum). This means that if the elevator cost the exact same amount of money to build and maintain, the maintenance and capital costs are distributed over ~2800 times fewer launches.
2800 is such a large number that it’s irrelevant if the EM launcher costs 100 billion to build and the elevator costs 10 billion, or vice versa. That capacity factor kills you.
What I think is you would use an EM launcher for cargo, and either conventional rockets or laser launch for humans.
One other note on laser launch : the amusing thing is that lasers are how they intend to power the elevator climber car. Laser launch, in a way, is just upscaling a system you have to build anyway.
50% efficiency from a cannon? That’s ludicrously optimistic. Let’s say that we’ve got a cannon launching straight up, firing projectiles 10 m long, with a density about equal to water. The downward force from gravity on such a projectile is rho_pALg, or a force per cross sectional area of about 100 kPa. The downward force from air resistance, meanwhile, is 0.5Crho_aA*v^2. Without futzing about with Reynolds numbers, let’s just say that the drag coefficient is of order 1. Launch speed is going to be something comparable to escape speed, 10^4 m/s, and air density is about 1 kg/m^3. This gives us a force per area from air resistance of order 10^8 kPa, or a thousand times greater than the gravitational force. And it gets much worse if you’re launching at the very shallow angle a long-barreled cannon would need.
Yes, there are some approximations I made there, but they work both ways, and the larger approximations are the ones that would make it even worse if accounted for. And yes, you can decrease the drag coefficient or increase the projectile length, but by three orders of magnitude?