What technology is most likely to take us to the stars??

[JBeukema]

Exactly what it says, an elevator going into space.

Frictio n aginst the atmosphere... sheering force... I see problems with this concept

 

[Josan]

Frictio n aginst the atmosphere... sheering force... I see problems with this concept

It's probably more realistic than you think!

 

[Ozymandyus]

Hate to agree with JB, but I find it incredibly unrealistic. We'll see wormholes before we see space elevators.

A cable going from the earth to moon - where would it be tethered? It would tear whatever it was apart as they move at different speeds. A tether to a space station in geosynchronous orbit would exert a ridiculous amount of downward pull on the space station. The weather effects on such an elevator would be outrageous, and would also significantly affect both ends of the tether as well as the trip up or down.

Beyond that, the cost of pulling such an elevator up (which would pull DOWN on the space station) would still be significant,approximately equal to just sending a rocket - it just isn't worth it.

 

[GoodKat]

Trigshot, I think you are confusing "black hole" with "wormhole".

Black holes are massive amounts of matter compressed into a single point of energy, causing an inescapable gravity well among other things.

Wormholes are where two points or areas in space-time touch, almost like a portal, possibly not just from one location to another, but one time to another.

 

[Trigshot]

Trigshot, I think you are confusing "black hole" with "wormhole".

I know the difference, I was simply referencing black holes because they are the only known likely source of actually creating a wormhole. In theory, a massive black hole may actually be a wormhole, but I would imagine testing that theory would be.... difficult.

 

[JBeukema]

I know the difference, I was simply referencing black holes because they are the only known likely source of actually creating a wormhole. In theory, a massive black hole may actually be a wormhole, but I would imagine testing that theory would be.... difficult.

only if you want to come back or emerge in one piece

 

[Darius]

Hate to agree with JB, but I find it incredibly unrealistic. We'll see wormholes before we see space elevators.

A cable going from the earth to moon - where would it be tethered? It would tear whatever it was apart as they move at different speeds. A tether to a space station in geosynchronous orbit would exert a ridiculous amount of downward pull on the space station. The weather effects on such an elevator would be outrageous, and would also significantly affect both ends of the tether as well as the trip up or down.

Beyond that, the cost of pulling such an elevator up (which would pull DOWN on the space station) would still be significant,approximately equal to just sending a rocket - it just isn't worth it.

A tether made of molecularly adjusted carbon nanotube crystals would be able to support it self upright, without putting a large amount of downward force on the space station, and is strong enough to withstand the conditions. In addition to this, a counter weight on the tether would provide centrifugal to keep it taught. As to how to power the elevator, a solar panel capable of absorbing a wider light spectrum (more then just infrared) could be attached to the bottom. Then, a high powered laser could be shot from the base of the tether that would reach the solar panel giving the elevator power to move itself upwards with its own device. From there, lasers shot from orbiting satellites could hit the solar panel. I'm sure by the time this is all possible (if possible), a material or combination of materials will exist that can withstand the weather effects that would occur on a space elevator.

 

[JBeukema]

In addition to this, a counter weight on the tether would provide centrifugal to keep it taught

Take a ball and tape it to another ball. Now,m start spinning one- the tether will wrap around the earth and either snap or send the station crashing into the earth unless you find some means of propulsion and can get around the wind, storms, and other environment forces

. As to how to power the elevator, a solar panel capable of absorbing a wider light spectrum (more then just infrared) could be attached to the bottom. Then, a high powered laser could be shot from the base of the tether that would reach the solar panel giving the elevator power to move itself upwards with its own device. From there, lasers shot from orbiting satellites could hit the solar panel.

You're counting on too many things going right

 

[Ozymandyus]

A tether made of molecularly adjusted carbon nanotube crystals would be able to support it self upright, without putting a large amount of downward force on the space station, and is strong enough to withstand the conditions. In addition to this, a counter weight on the tether would provide centrifugal to keep it taught. As to how to power the elevator, a solar panel capable of absorbing a wider light spectrum (more then just infrared) could be attached to the bottom. Then, a high powered laser could be shot from the base of the tether that would reach the solar panel giving the elevator power to move itself upwards with its own device. From there, lasers shot from orbiting satellites could hit the solar panel. I'm sure by the time this is all possible (if possible), a material or combination of materials will exist that can withstand the weather effects that would occur on a space elevator.

The elevator pulling itself upwards would pull the space station DOWNWARDS. I'm pretty certain even a carbon nanotube structure that is a mile+ long would still be breakable and bendable by the sorts of forces we are talking about here, and constructing such a structure would cost such a ridiculous amount of money - I find it completely unfeasible. A rigid structure this tall is just a bad idea. Beyond that, it would have to be a carbon fiber nanotube pyramid, as anything else would collapse into its supports from the weight.

Energy will be MUCH cheaper by the time such a thing would be feasible, and it would be much easier to just use such a laser to power a shuttle into space rather than an elevator - ultimately the forces involved in moving mass and then slowing it down as it reaches its destination are the same - theres no reason to use such a structure.

Back on topic - teleportation is another possibility - I think its more likely than star trek type hyperspace drives depending on what the claims for science behind them are. Being able to interact with a fourth spatial dimension would clearly allow for all kinds of travel, and whether it would be more analogous to hyperdrives or stargates, I'm not really sure. Probably stargates.

 

[Darius]

The elevator pulling itself upwards would pull the space station DOWNWARDS. I'm pretty certain even a carbon nanotube structure that is a mile+ long would still be breakable and bendable by the sorts of forces we are talking about here, and constructing such a structure would cost such a ridiculous amount of money - I find it completely unfeasible. A rigid structure this tall is just a bad idea. Beyond that, it would have to be a carbon fiber nanotube pyramid, as anything else would collapse into its supports from the weight.

Energy will be MUCH cheaper by the time such a thing would be feasible, and it would be much easier to just use such a laser to power a shuttle into space rather than an elevator - ultimately the forces involved in moving mass and then slowing it down as it reaches its destination are the same - theres no reason to use such a structure.

Back on topic - teleportation is another possibility - I think its more likely than star trek type hyperspace drives depending on what the claims for science behind them are. Being able to interact with a fourth spatial dimension would clearly allow for all kinds of travel, and whether it would be more analogous to hyperdrives or stargates, I'm not really sure. Probably stargates.

An elevator that pushes itself upwards doesn't put force on the space station. The strength of a carbon nanotube is extremely complex. In terms of cost, all concepts of getting humans into space are incredibly expensive.

The way shuttles would work, a new shuttle would have to be built each trip into space and back, resulting in ridiculous costs.

Teleportation would be difficult, since it involves de-atomization and then transferring the atoms by some means in order to re-atomize the object/being elsewhere.

 

[Aught3]

I'm in agreement with Darius, not only are space elevators feasible but they represent the best way of getting payload into space. It is incredibly expensive to send anything into space and the amount of fuel it requires takes up most of the ship's volume anyway. Although a space elevator would be initially expensive to build, the cost of payloads would be dramatically reduced.

The elevator pulling itself upwards would pull the space station DOWNWARDS

The idea is to attach the tether to a counterweight which swings around Earth providing centripetal (not centrifugal) force to the cable - this force keeps it taught as the elevator climbs upwards.

I'm pretty certain even a carbon nanotube structure that is a mile+ long would still be breakable and bendable by the sorts of forces we are talking about here

I haven't heard the weather objection before but these nanotubes are incredibly strong. One the thickness of a human hair is expected to be able to support the weight of a car. Plus the base of the space elevator would be situated in the doldrums so should not experience extreme weather like hurricanes.

constructing such a structure would cost such a ridiculous amount of money

Unfortunately, this is correct :cry: I think it would be a worthwhile investment though.

 

[Ozymandyus]

How do you envision such a structure... The counterweight would have to weigh something enormous to keep a cable that would weigh many many tons taught. The tensile strength of the cable would have to be off the charts, as well as the strength of the tether point on the earth that is being pulled by thousands of tons of centrifugal force. Weathering effects on the cable would be significant, the difference in environment from earth surface to space would do some interesting things to a carbon nanofiber cable I imagine - there would be weak points in the tensile strength almost definitely. Taking into account varying gravitational effects of the moon and the sun on this counterweight is another problem - not sure exactly how it might affect it but it begins to be significant at the masses we are talking about here.

I can't see how it's that much cheaper to accelerate something with a cable than without, if you do it right. If we instead used a tunnel of electromagnets to 'shoot' shuttles/cargo into space like a rail gun, it could potentially be nearly as energy efficient as moving such an elevator, and would be able to do more than move cargo to a single point.

But then again, I'm not in materials science aerospace nor architecture so my opinion is just off the top of my head problems with it. I'm sure someone has already thought of this more than I could so if a real scientist says its feasible I'll believe it, just doesn't seem so to me.

 

[Aught3]

How do you envision such a structure... The counterweight would have to weigh something enormous to keep a cable that would weigh many many tons taught.

Yes, around about 600 tonnes to be somewhat exact. Building the initial structure is going to be the biggest problem of course - all the materials will have to be slowly shipped up and assembled piece by piece. But hey, we did a pretty good job with the international space station which weighs about 280 tonnes so I don't think it's outside the realms of possibility to build it. And once it's done it opens the way for much bigger construction projects.

The tensile strength of the cable would have to be off the charts, as well as the strength of the tether point on the earth that is being pulled by thousands of tons of centrifugal force.

Ozy! Not centrifugal, centripetal But again you're right that's why the idea had to wait until something like carbon nanotubes to start becoming feasible. It may be true that the nanotubes are not strong enough, but at least we're getting closer to the type of materials we would need.

Taking into account varying gravitational effects of the moon and the sun on this counterweight is another problem - not sure exactly how it might affect it but it begins to be significant at the masses we are talking about here.

As it is so close to Earth I doubt other celestial bodies will have a huge effect. Especially considering the fact that we can get the ISS to work.

I can't see how it's that much cheaper to accelerate something with a cable than without, if you do it right. If we instead used a tunnel of electromagnets to 'shoot' shuttles/cargo into space like a rail gun, it could potentially be nearly as energy efficient as moving such an elevator, and would be able to do more than move cargo to a single point.

The idea is to be slow and steady, avoiding the need for huge, energy expensive acceleration to overcome the gravity of the planet. Maybe there are other ideas that would work better, but space elevators is the idea that excites me the most.

As for the atmosphere/space effects I have read of a silver coating that is supposed to protect the nanotubes from ozone so it seems like those problems are, at least, being considered.

 

[Ozymandyus]

There are still some substantial reactive centrifugal forces when talking about rotating bodies of this mass are there not? I'm not talking about centrifugal force as it is commonly (mis)used. Although I may have confused myself by thinking about the initial inertial stresses involved in accelerating such a counterweight, which isn't an issue in this sort of case.

In any case, tidal effects seem that they would be more of a problem with a tethered mass like this than a free falling mass like the ISS that can freely adjust to such stresses. Sorry that I keep talking about this, I love speculative technology. Had never read anything on space elevators for whatever reason so am interested but skeptical as I am with all new information =P.

 

[Aught3]

There are still some substantial reactive centrifugal forces when talking about rotating bodies of this mass are there not? I'm not talking about centrifugal force as it is commonly (mis)used. Although I may have confused myself by thinking about the initial inertial stresses involved in accelerating such a counterweight, which isn't an issue in this sort of case.

Well from certain reference frames you can talk about a centrifugal force on the Earth. But the important point is the tension in the tether providing centripetal force to the counterweight in order to keep it swinging in a circle.

In any case, tidal effects seem that they would be more of a problem with a tethered mass like this than a free falling mass like the ISS that can freely adjusted to such stresses.

I don't see all that much difference, instead of the force being provided by gravity it is provided by the tension in the tether. The counterweight would be about 100,000 km up whereas the moon is about 380,000 km away, take into account the relative sizes of the Earth and moon - but I'm not 100% sure might be a valid concern.

 

[JBeukema]

teleportation is another possibility

last I heard, teleportation was only successful at the atomic level
What happens the day a plane hits the tether? 0.0

 

[Sparky]

Looks like I hit an interesting topic with the space elevator

I think that with the current research going on into nanotechnology and materials sciences (my university is one that is doing a lot of research in these areas) that it won't take too long for incredibly strong nanofibres to be developed that will hopefully get this project off the ground (sorry, that is a terrible pun :| ). We already have carbon nanotubes which are 50 times as strong as steel in a weight/weight ratio. Who is to say that even stronger materials won't be made?

 

[Ozymandyus]

Here's my vision: Estimates on top speeds of mag-lev trains in frictionless tunnels (evacuated tubes) are up to 6700km/hour... Cargo could be launched towards space from these same tunnels we may use for transport one day. The mag-lev track heading wherever could have an associated branch which would only be used for space launches. When a launch vehicle approached, the tracks would switch, it would branch off, adjust its heading upward and launch the vehicle towards space. Wherever the track goes that is at the highest altitude would be ideal for this.

The cost of accelerating the space train (or shuttle or whatever) would be minimal, less even than accelerating your elevator, because of the lack of friction and effective power source. It would still require some thrust after launch to reach escape velocity, but considering that you could launch very heavy payloads at low energy costs with this method you would have room for fuel. The costs of making the launcher would be relatively low, the track would already be there if we are already building these tunnels for long distance mass transit - only an additional kilometer or two of track would need to be added. And the energy required to bring that vehicle to top speed would be low, as I mentioned.

This is all taking into account the currently available technologies - advances in technology like carbon nanotube materials and such can only make it more efficient.

 

[Aught3]

Yeah a maglev based spacelaunch track helps in terms of saving fuel. However, you are still would only be traveling at about 2km/s and would need significant amounts of fuel to reach the 11 km/s escape velocity. If you wanted to enter orbit or return to Earth you would need even more. This means the spacelaunch track idea would pale in comparison to the payloads a space elevator could carry.

 

[Ozymandyus]

The first 2km/s are the hardest. 2km/s would get you far enough to not have to deal with any meaningful air friction, and your thrust would be much more effective. You would probably be able to cut out the need for multi-stage rockets and get past the need for designing different engines for different altitudes.

Still, I admit that when I looked at the 6700km/hour number I was a bit sad that it wasn't a larger percentage of the escape velocity needed. But, advances in technology could still bring up this number, and I think its the most useful technique in terms of its other applications as well. It's still better than the Mach 17 that scram jets can go. And I can actually imagine of the building process of such a method, whereas the carbon nanofiber tether just breaks my mind in terms of how you actually Build it and what you do when it gets hit by a meteor or space debris.