It will likely take 20 or 30 years to get the ribbon done.
You don't know that. Materials scientists have said as little as 5, as much as never. Besides, as I've said elsewhere, if it really looks like it's nearly impossible, just lower the requirements and up the taper. The climber still works for both designs.
At that point the climber would be like the Saturn V is today: Great technology, but its so old that spare parts aren't available, so we'll have to build a new one one from scratch.
They're not talking about producing the climbers. They're talking about designing them.
Curiously enough, designs are immortal. Which is why the Crew Exploration Vehicle is going back to a modified version of a previous engine design. What makes this example even more appropriate is that they're going to a modified J-2 (used on, you know, the Saturn V) engine.
Do you know how to build a bearing that will last that long? I don't. But they're trying to find out. And once they do find one, it's not going to matter how long it takes the ribbon to become available.
I don't understand this idea of "wait until the ribbon's ready." What's going to happen? This isn't like the computer world where things go obsolete in a few years. There are real serious engineering problems here, and they have resources to solve them. I'm definitely missing something.
The point is that the cable is by far the hardest part.
You don't know that. Ask a materials scientist working on carbon nanotubes how long it will take to get that cable, and you might get an answer of "5 years". Ask an engineer how long it will take to design that climber (and the subsequent power delivery system) and they might say "5 years" as well.
It's a difficult problem, and the climber's power needs drive the power delivery system. So it makes sense to work on the climber first.
When we are 75% of the way to producing an adequate cable we can start the other parts.
That's an extremely naive business model. They're working on the two things in parallel.
like building the lunar lander for Apollo but having boosters no larger than a bottle rocket.
You think people weren't planning the lunar lander well in advance of having the launch capability of reaching the moon?
I said "mostly". Planes, and balloons, get above 99.99% of the atmosphere. The X-15 got to 99.9...lots of 9s... percent of the atmosphere. I'll say it again. We don't use rockets to get above the atmosphere. That's my point.
The Earth rotates once every 24 hours (again, approximately). pi * d gives a distance covered of around about 40,000 km. That's a speed (not a velocity; velocity has a direction) of 1,666 kph.
What's impressive is that you wrote about 4 paragraphs commenting essentially on the fact that I neglected to use the word "angular" in front of velocity.
The atmosphere is thinner and the long barrel would allow for slower acceleration or higher muzzle velocity.
It's not the atmosphere that really matters. It's the velocity. You need to get the thing up to near escape velocity. That's 11.2 km/s at the surface of the Earth. That's Mach 32. Yes, the atmospheric density is down by a factor of 2, but it's Mach 32! The atmospheric losses are going to be enormous, which means you need to accelerate it to even higher speeds.
A 1 km acceleration range would require 62,720 m/s^2 (11.2 km/s squared divided by 2 divided by 1 km). That's roughly 6272 gees. It's unlikely that anything would survive that amount of acceleration (it'd kill all humans a long, long time before). For reference, the shuttle's acceleration at launch? One gee. They have about 3 gees maximum later.
And if you want to fire with less velocity, and then use a rocket? Let's say you wanted to replace the SRBs on the shuttle. The mass of the Shuttle by itself is ~100,000 kg. The mass of the Shuttle plus the tank (no SRBs) is almost 10 times that (it's like 850,000 kg).
The reason rockets win out over electromotive propulsion is because they have a freaking long time to accelerate.
No is asking for "arbitrarily high trust" from a rail gun...well, save only you.
Height reached by a rail gun is just (v^2 / 2a). Higher you go, the faster you need to go.
If you want to accelerate a big mass to a high altitude, you need a huge thrust. If you say "okay, we'll just do a two-stage launch" that means you now need to thrust the rocket, and all of its fuel. Which is a huge mass.
There are going to be fundamental constraints here.
Planes and Balloons can't get above the atmosphere, because they both need an atmosphere in order to work.
I word things very carefully. Read it again. I said "planes can pretty much do that." I was actually thinking about commercial airlines, which fly above 72% of the atmosphere.
But, of course, there's this nugget from Wikipedia:
99.99999% of the atmosphere is below the highest X-15 plane flight on August 22, 1963 which reached an altitude of 354,300 ft or 108 km.
Balloons typically reach altitudes of 100K feet, which is above all but a fraction of a percent (it's a few Torr).
simply by building our velocity high enough to escape velocity while in the atmosphere and letting inertia take us out.
Ignoring that whole "air resistance" and "speed of sound" thing.
And curiously, if it wasn't for those two things, we could do that right now.
We use rockets for velocity, not altitude. If you doubt me, consider that the Space Shuttle's two solid rocket boosters shut off at lower altitudes than the X-15. Why don't we use a jet to boost the Shuttle to that altitude? Because the SRBs get the Shuttle to a much, much higher speed.
There's nothing "special" about Geosynchronous orbit which means you can "get the velocity from the Earth".
I get velocity from the Earth all the time. It's called standing on the ground. (Curiously enough, if I didn't, I would start flowing in these little circly patterns, called Hadley cells, which are what happens when you have a viscous medium gravitationally sitting on top of a rotating sphere. If the atmosphere extended enough, it essentially wouldn't be rotating.)
That's what special about geosynchronous orbit. Orbital velocity is slow enough that I can use the Earth's rotation to supply it.
You DO have velocity.
Which I got... from the Earth. Like, when a plane lands, after heading west, how the Earth speeds it up in a matter of seconds?
The idea is at that height, escape velocity is negligable.
It's not "negligible" - it's two thousand miles an hour (curiously, roughly 1 km/s). It's just neglible in the rotating frame of the Earth.
I guess you could but it's probably an even worse return; which you seemingly agree on.
No - that's my point. If you want to launch the thing to say, 100,000 feet, there's no way a rail gun would compete with a direct rocket launch. Sure, you lose 70% of your energy in splitting water into hydrogen and oxygen - but you'd lose 90% in air resistance by only giving an initial impulse.
Besides, you can't launch something to 100,000 feet easily. The object would be travelling very supersonically, and the air resistance would be wacky beyond all measure.
Besides, improved safety is only of the other tangibles of the rail approach.
No, it isn't. Now, the fuel wouldn't fail - but the structural supports might. You're upping the structural requirements of launch by orders of magnitude. That's just not feasible.
Again, that's exactly why people get excited about a rail gun launcher.
What? I mentioned that because it's not possible to have an arbitrarily high thrust from a rail gun. At some point you're just asking way too much current.
The challenges of a space elevator aren't in the climber; they're in the cable.
C'mon. That's not true. The main reason it seems like this is because you think you know how to build the climber, but you have no idea how to build the cable. Ask a materials scientist who's working on carbon nanotubes, and they might disagree with you.
Plus, you do not need a 100 GPa cable. You need a 100 GPa cable for a small taper. At 50 GPa the taper becomes... well, large, but not unreasonably large. It would just cost a lot more.
There are a lot of issues with the climber design. A lot. Speed, reliability, weight, and power. Reliability in particular will take a lot of time to nail down. It makes sense to tackle that one first, because it can be done in parallel with the cable design, and in addition, the third major challenge (power delivery) can't really be done until the climber design is finalized.
So you've got three difficult tasks - the cable, the climber, and the power delivery system. The last two are coupled. What makes sense is having two separate tasks, one of which handles the cable, the other the climber, and then the power delivery system. Oh look! That's exactly what they're doing.
Given our lack of experience in building cheap vehicles that can travel 100,000 km with zero failures (with low power, in vacuum) I think it's safe to say that all parts of the elevator are difficult.
No, not necessarily. It really depends on the exit velocity of the mass leaving the earth.
Uh... what?
What do you mean by exit velocity? Fundamentally the only way you could "speed up" the Earth with a space elevator is by having something climb up, and then fire bojillions of rockets while holding onto the elevator.
(Which, of course, would tear the elevator).
Otherwise you're always slowing down the Earth. The mere act of climbing up the elevator slows down the Earth's rotation.
That's all well and true, but none of this is all that impressive on the tiny scale they're currently working at.
They're not testing the cable. They're testing the climber. You can build up the reliability of a climber on any scale. Just have it go up and down a bazillion times.
Right now they're just testing the initial design.
and the mechanical climbers that install those cable strand by strand have climbed much higher than a few hundred feet to pull it off decades ago.
Very, very different engineering concerns (and "1500 feet" is not "a few hundred", unless your definition of "a few" is somehow "15").
Why didn't you just use it to split water into hydrogen and oxygen, and use that? It's less efficient, sure, but depending on how high up you plan on shooting the object with the rail gun, you can still win out.
Plus, the amount of thrust required to lift an entire rocket is rather large. At some point you've got to worry about the sheer amount of current you need to shove through the wires. Even superconductors have upper limits.
The center of mass has to be at geosynchronous orbit. That means that the elevator has to extend significantly beyond geosynchronous orbit without a counterweight. Yah, it is a significant fraction of the distance to the moon.
The extra length isn't really a problem. You just spool it out behind you. And if it does become a problem, then you use a counterweight.
The extra length actually has a lot of advantages. You can continue to crawl past geosync, and you're at higher than orbital velocity. If you go all the way to the edge of the elevator, and let go, poof, you're off to Jupiter. It's worth the (small) excess hassle.
Will the Earth spin slower (albeit just little slower) due to loss of the mass?
Yes. But until the rest of the Earth decides they really don't like the US, and decide to send the entire continent of North America into space, it's likely that it won't be noticeable.
(Canada, Mexico and others will just be casualties for the greater good.)
Then again, maybe that won't be that far off...
Seriously, though, the Earth is big. Really, really, really big. Even if we up and lifted an entire continent off the planet, it probably wouldn't slow the planet down more than a minute in a day.
Does the firm have any ideas on how to avoid tremendous death and destruction if this immensely long cable were to fall to the Earth, possibly hitting certain areas twice as badly if it were long enough to wrap more than once around?
Yes. They're going to deploy a massive cushion around the Earth, consisting of a total of about 5000 trillion metric tons of gas. Roughly 78% will be nitrogen, and 21% will be oxygen.
If the cable breaks, the lower half will encounter this cushion at extremely high velocities, ripping it apart and causing it to flutter harmlessly to the ground.
No news about whether or not they'll patent the idea.
Personally I'm surprised no one has tried just shooting things into space.
Oh, and I didn't see this. Fundamentally, this is a bad idea. First off, the idea of a modified Howitzer? That's just explosive propulsion. This is fundamentally the same idea as a rocket - it's just that a rocket is far, far more effective in terms of thrust per unit mass.
You could imagine electromotive propulsion - a rail gun - but the problem with that is that you're imparting all of your momentum in the thickest part of the atmosphere, at which point it would just be bled away as air resistance. You'd need to supply a ridiculous amount of energy to do it, and the craft would have to have a ridiculous amount of stress support and heat resistant material. It gets to the point where there is no way that it would ever be economically feasible.
On an atmosphere-free planet, though, it does become pretty feasible, though a space elevator is likely to be more generically useful for large cargo.
I have to agree with the GP it feels to me like the ribbon is the more difficult part
Of course it does. For one thing, you can understand how a climber can climb. So if you see one climbing, you say "hey, that's easy, I could've built that." But designing something that reliable and that optimized is very, very difficult.
I'd imagine if you were a material scientist working with carbon nanotubes, you might feel that the ribbon is easier. Especially because we really don't have to get all the way to 50-100 GPa. We can just taper it more, which will cost a lot more and have other problems, but we can design around those then.
You can, for instance, build a space elevator on the Moon out of, say, Kevlar. You'd still need a super-ultra reliable climber, though.
If it takes 6 months to get something into space it may end up being cheaper to use conventional methods especially if only one or two climbers can operate at a time.
First, it might be cheaper in terms of getting-to-orbit, but that's not the whole story. You don't need to design for stresses with a space elevator, for one. And second, keep in mind that once you climb to the end of the space elevator, you're moving very, very fast. You can let go of the cable and you'll have enough momentum to get to Jupiter.
Second, if it's too slow, there's an easy solution. Drop more elevators. The expensive part of the elevator is launching the first mass into space. Once it's up there, if you need to increase your capacity, it's a very small marginal cost.
There is absolutely no way that a space elevator wouldn't completely revolutionize space travel.
but is that more feasible than 62,000 miles of carbon nanotubing?
What do you mean by "feasible"? Possible? Yah, sure. No problem.
Do you mean "forseeably possible in the near future"? They probably both are.
No, the technology to beam power like that currently does not exist. Precursors to it definitely do. No, the technology to build a cable that strong currently does not exist, but precursors do. And no, the technology to build a climber that reliable, light, and low power doesn't exist either.
They're working on it. It's engineering. What do you want? Best way to build something is to try it, figure out what works, and try, try again.
Really? Are you sure? Can you build a bearing for a 20-cm wheel that will be able to turn 500 million times with zero chance of failure? And can you do it lightly? And in vacuum?
While we don't have the ribbon yet, we don't have the climber, and we don't have the power delivery system either. That's why it's called inventing. They're doing something that hasn't been done before.
And when you've got multiple independent difficult problems, you might as well work on all of them at once. Which they are doing.
Go and read the talks on building the climber at the last space elevator conference before you call it "trivial".
You don't need a counterweight. Counterweights are pretty much counterproductive - it's cheaper just to make the cable longer.
Oddly enough, we don't know how to get to near light speed. We do have significant engineering information on how to build a space elevator. Go out and read it. If you think it's as difficult as reaching near light speed, or moving an asteroid, you're crazy.
But who knows, maybe they do mean 62,000 miles? I thought the elevator's main purpose was to get things in and out of just the atmosphere, as to avoid all the problems with expensive and dangerous rocket launches and dangerous re-entries.
We don't use rocket to get above the atmosphere. Planes can pretty much do that. Balloons can (and regularly do) do that. That's the easy part.
We use rockets to get velocity, because you need a ridiculous velocity in order to actually orbit the Earth at a low height.
You do not, however, need a ridiculous velocity in order to orbit at a very, very high height. At geosynchronous orbit, you need no velocity, because you've already got the speed from the Earth's rotation.
So yes, they do mean 62,000 miles (100,000 km). And the benefits you get from a cable like that are insane. Costs/pound to launch things into space become negligible. Transit to the Moon becomes cheap and fast, because the end of the cable is actually moving faster than orbital velocity.
In fact, if you climbed all the way to the end of the cable, and let go with good timing, you'd end up past Jupiter (and on a direct trajectory, too, no mucking about in Lagrange points).
Yes, it's moderately insane. Yes, it's ridiculously difficult. But it would also end up being one of the biggest changes in human industry that has ever occurred. Space solar power plants beaming down power becomes feasible. Large-scale structures built in space become easy.
Plus, once we get the technology, we can build them on other planets as well. The Moon. Mars. It basically eliminates almost all of the serious difficulties of space flight.
Yah. That's the point. The cable goes to geosynchronous orbit.
Yes. That's long. But it's not as insane as you might think. The biggest concern is the tensile strength of the cable itself. Once (if, and it's a tough "if") that gets solved, it's just a matter of a really really big spool of cable.
Don't get me wrong. It's still moderately insane. It'll be #1 on the Discovery Channel's modern engineering marvels if it's completed - by a large margin. But it's not completely ridiculous insane.
...but it seems like the climber is the easy-ish part of a space elevator.
Far from it. All of the components of a space elevator will be revolutionary, not just the ribbon. The climber's mechanical parts have to work flawlessly for about 100,000 km. The actual problem of gripping a cable isn't trivial, either. And it needs to be very low weight. Oh, and very low power. And just to make things even more fun, it'll need to work in vacuum as well.
If you read some of the papers on concerns for the climber at the space elevator conference, you realize that there's nothing easy about this. It's unsurprising that the climber is seeing the most progress first, but that first concern (perfect reliability over 100,000 km) will take a long time, so better to start now.
I mean, reading the article, it's obvious it's a parody.
I think they know.
lampoon (lm-pn') pronunciation n.
1. A written attack ridiculing a person, group, or institution. See synonyms at caricature.
2. A light, good-humored satire.
However, the original article from ABC is, in fact, serious. It's also so ridiculously inaccurate, it's scary. Quoth I: "Predators are using Nintendo DS anywhere in the world. And it's going to be really hard to track down those individuals because of course, they're on a wireless network from a hotspot such as a coffee shop." which is totally false - as PictoChat only works DS-to-DS, which means the person they're talking to is a few feet away.
I dunno about you, but I think I can track a DS user who's a few feet away. I'm probably going to look for the guy holding a Nintendo DS who's not me.
But then again, this is why I don't watch local news. To paraphrase the Daily Show, "Is the media too sensationalist? Find out tonight, in our no-holds-barred expose that just might save your family's life."
Slashdot Mirror
It will likely take 20 or 30 years to get the ribbon done.
You don't know that. Materials scientists have said as little as 5, as much as never. Besides, as I've said elsewhere, if it really looks like it's nearly impossible, just lower the requirements and up the taper. The climber still works for both designs.
At that point the climber would be like the Saturn V is today: Great technology, but its so old that spare parts aren't available, so we'll have to build a new one one from scratch.
They're not talking about producing the climbers. They're talking about designing them.
Curiously enough, designs are immortal. Which is why the Crew Exploration Vehicle is going back to a modified version of a previous engine design. What makes this example even more appropriate is that they're going to a modified J-2 (used on, you know, the Saturn V) engine.
Do you know how to build a bearing that will last that long? I don't. But they're trying to find out. And once they do find one, it's not going to matter how long it takes the ribbon to become available.
I don't understand this idea of "wait until the ribbon's ready." What's going to happen? This isn't like the computer world where things go obsolete in a few years. There are real serious engineering problems here, and they have resources to solve them. I'm definitely missing something.
The point is that the cable is by far the hardest part.
You don't know that. Ask a materials scientist working on carbon nanotubes how long it will take to get that cable, and you might get an answer of "5 years". Ask an engineer how long it will take to design that climber (and the subsequent power delivery system) and they might say "5 years" as well.
It's a difficult problem, and the climber's power needs drive the power delivery system. So it makes sense to work on the climber first.
When we are 75% of the way to producing an adequate cable we can start the other parts.
That's an extremely naive business model. They're working on the two things in parallel.
like building the lunar lander for Apollo but having boosters no larger than a bottle rocket.
You think people weren't planning the lunar lander well in advance of having the launch capability of reaching the moon?
I said "mostly". Planes, and balloons, get above 99.99% of the atmosphere. The X-15 got to 99.9...lots of 9s... percent of the atmosphere. I'll say it again. We don't use rockets to get above the atmosphere. That's my point.
The Earth rotates once every 24 hours (again, approximately). pi * d gives a distance covered of around about 40,000 km. That's a speed (not a velocity; velocity has a direction) of 1,666 kph.
What's impressive is that you wrote about 4 paragraphs commenting essentially on the fact that I neglected to use the word "angular" in front of velocity.
The atmosphere is thinner and the long barrel would allow for slower acceleration or higher muzzle velocity.
It's not the atmosphere that really matters. It's the velocity. You need to get the thing up to near escape velocity. That's 11.2 km/s at the surface of the Earth. That's Mach 32. Yes, the atmospheric density is down by a factor of 2, but it's Mach 32! The atmospheric losses are going to be enormous, which means you need to accelerate it to even higher speeds.
A 1 km acceleration range would require 62,720 m/s^2 (11.2 km/s squared divided by 2 divided by 1 km). That's roughly 6272 gees. It's unlikely that anything would survive that amount of acceleration (it'd kill all humans a long, long time before). For reference, the shuttle's acceleration at launch? One gee. They have about 3 gees maximum later.
And if you want to fire with less velocity, and then use a rocket? Let's say you wanted to replace the SRBs on the shuttle. The mass of the Shuttle by itself is ~100,000 kg. The mass of the Shuttle plus the tank (no SRBs) is almost 10 times that (it's like 850,000 kg).
The reason rockets win out over electromotive propulsion is because they have a freaking long time to accelerate.
No is asking for "arbitrarily high trust" from a rail gun...well, save only you.
Height reached by a rail gun is just (v^2 / 2a). Higher you go, the faster you need to go.
If you want to accelerate a big mass to a high altitude, you need a huge thrust. If you say "okay, we'll just do a two-stage launch" that means you now need to thrust the rocket, and all of its fuel. Which is a huge mass.
There are going to be fundamental constraints here.
I word things very carefully. Read it again. I said "planes can pretty much do that." I was actually thinking about commercial airlines, which fly above 72% of the atmosphere.
But, of course, there's this nugget from Wikipedia:
Balloons typically reach altitudes of 100K feet, which is above all but a fraction of a percent (it's a few Torr).
simply by building our velocity high enough to escape velocity while in the atmosphere and letting inertia take us out.
Ignoring that whole "air resistance" and "speed of sound" thing.
And curiously, if it wasn't for those two things, we could do that right now.
We use rockets for velocity, not altitude. If you doubt me, consider that the Space Shuttle's two solid rocket boosters shut off at lower altitudes than the X-15. Why don't we use a jet to boost the Shuttle to that altitude? Because the SRBs get the Shuttle to a much, much higher speed.
There's nothing "special" about Geosynchronous orbit which means you can "get the velocity from the Earth".
I get velocity from the Earth all the time. It's called standing on the ground. (Curiously enough, if I didn't, I would start flowing in these little circly patterns, called Hadley cells, which are what happens when you have a viscous medium gravitationally sitting on top of a rotating sphere. If the atmosphere extended enough, it essentially wouldn't be rotating.)
That's what special about geosynchronous orbit. Orbital velocity is slow enough that I can use the Earth's rotation to supply it.
You DO have velocity.
Which I got... from the Earth. Like, when a plane lands, after heading west, how the Earth speeds it up in a matter of seconds?
The idea is at that height, escape velocity is negligable.
It's not "negligible" - it's two thousand miles an hour (curiously, roughly 1 km/s). It's just neglible in the rotating frame of the Earth.
"Negligible" describes the total mass of the Earth's crust (you know, the part we live on) compared to the whole Earth.
You need a whole other category for this. Even "infinitesimal" doesn't seem good enough.
Use that how? As a rocket?
Uh, yes. That's kindof what the Shuttle uses.
I guess you could but it's probably an even worse return; which you seemingly agree on.
No - that's my point. If you want to launch the thing to say, 100,000 feet, there's no way a rail gun would compete with a direct rocket launch. Sure, you lose 70% of your energy in splitting water into hydrogen and oxygen - but you'd lose 90% in air resistance by only giving an initial impulse.
Besides, you can't launch something to 100,000 feet easily. The object would be travelling very supersonically, and the air resistance would be wacky beyond all measure.
Besides, improved safety is only of the other tangibles of the rail approach.
No, it isn't. Now, the fuel wouldn't fail - but the structural supports might. You're upping the structural requirements of launch by orders of magnitude. That's just not feasible.
Again, that's exactly why people get excited about a rail gun launcher.
What? I mentioned that because it's not possible to have an arbitrarily high thrust from a rail gun. At some point you're just asking way too much current.
The challenges of a space elevator aren't in the climber; they're in the cable.
... well, large, but not unreasonably large. It would just cost a lot more.
C'mon. That's not true. The main reason it seems like this is because you think you know how to build the climber, but you have no idea how to build the cable. Ask a materials scientist who's working on carbon nanotubes, and they might disagree with you.
Plus, you do not need a 100 GPa cable. You need a 100 GPa cable for a small taper. At 50 GPa the taper becomes
There are a lot of issues with the climber design. A lot. Speed, reliability, weight, and power. Reliability in particular will take a lot of time to nail down. It makes sense to tackle that one first, because it can be done in parallel with the cable design, and in addition, the third major challenge (power delivery) can't really be done until the climber design is finalized.
So you've got three difficult tasks - the cable, the climber, and the power delivery system. The last two are coupled. What makes sense is having two separate tasks, one of which handles the cable, the other the climber, and then the power delivery system. Oh look! That's exactly what they're doing.
Given our lack of experience in building cheap vehicles that can travel 100,000 km with zero failures (with low power, in vacuum) I think it's safe to say that all parts of the elevator are difficult.
No, not necessarily. It really depends on the exit velocity of the mass leaving the earth.
Uh... what?
What do you mean by exit velocity? Fundamentally the only way you could "speed up" the Earth with a space elevator is by having something climb up, and then fire bojillions of rockets while holding onto the elevator.
(Which, of course, would tear the elevator).
Otherwise you're always slowing down the Earth. The mere act of climbing up the elevator slows down the Earth's rotation.
That's all well and true, but none of this is all that impressive on the tiny scale they're currently working at.
They're not testing the cable. They're testing the climber. You can build up the reliability of a climber on any scale. Just have it go up and down a bazillion times.
Right now they're just testing the initial design.
and the mechanical climbers that install those cable strand by strand have climbed much higher than a few hundred feet to pull it off decades ago.
Very, very different engineering concerns (and "1500 feet" is not "a few hundred", unless your definition of "a few" is somehow "15").
You spend renewable energy on the rail gun
Why didn't you just use it to split water into hydrogen and oxygen, and use that? It's less efficient, sure, but depending on how high up you plan on shooting the object with the rail gun, you can still win out.
Plus, the amount of thrust required to lift an entire rocket is rather large. At some point you've got to worry about the sheer amount of current you need to shove through the wires. Even superconductors have upper limits.
If balloons can get us out of the atmosphere
They do.
why not use balloons to make a very fast form of transit that is made possible by having very little air friction?
Because you still have to go up, and then down. The economics of something like that completely don't work.
Plus, people didn't pay to travel in a supersonic plane, much less anything faster. Conventional travel is fast enough.
The center of mass has to be at geosynchronous orbit. That means that the elevator has to extend significantly beyond geosynchronous orbit without a counterweight. Yah, it is a significant fraction of the distance to the moon.
The extra length isn't really a problem. You just spool it out behind you. And if it does become a problem, then you use a counterweight.
The extra length actually has a lot of advantages. You can continue to crawl past geosync, and you're at higher than orbital velocity. If you go all the way to the edge of the elevator, and let go, poof, you're off to Jupiter. It's worth the (small) excess hassle.
Will the Earth spin slower (albeit just little slower) due to loss of the mass?
Yes. But until the rest of the Earth decides they really don't like the US, and decide to send the entire continent of North America into space, it's likely that it won't be noticeable.
(Canada, Mexico and others will just be casualties for the greater good.)
Then again, maybe that won't be that far off...
Seriously, though, the Earth is big. Really, really, really big. Even if we up and lifted an entire continent off the planet, it probably wouldn't slow the planet down more than a minute in a day.
Does the firm have any ideas on how to avoid tremendous death and destruction if this immensely long cable were to fall to the Earth, possibly hitting certain areas twice as badly if it were long enough to wrap more than once around?
Yes. They're going to deploy a massive cushion around the Earth, consisting of a total of about 5000 trillion metric tons of gas. Roughly 78% will be nitrogen, and 21% will be oxygen.
If the cable breaks, the lower half will encounter this cushion at extremely high velocities, ripping it apart and causing it to flutter harmlessly to the ground.
No news about whether or not they'll patent the idea.
Personally I'm surprised no one has tried just shooting things into space.
Oh, and I didn't see this. Fundamentally, this is a bad idea. First off, the idea of a modified Howitzer? That's just explosive propulsion. This is fundamentally the same idea as a rocket - it's just that a rocket is far, far more effective in terms of thrust per unit mass.
You could imagine electromotive propulsion - a rail gun - but the problem with that is that you're imparting all of your momentum in the thickest part of the atmosphere, at which point it would just be bled away as air resistance. You'd need to supply a ridiculous amount of energy to do it, and the craft would have to have a ridiculous amount of stress support and heat resistant material. It gets to the point where there is no way that it would ever be economically feasible.
On an atmosphere-free planet, though, it does become pretty feasible, though a space elevator is likely to be more generically useful for large cargo.
I have to agree with the GP it feels to me like the ribbon is the more difficult part
Of course it does. For one thing, you can understand how a climber can climb. So if you see one climbing, you say "hey, that's easy, I could've built that." But designing something that reliable and that optimized is very, very difficult.
I'd imagine if you were a material scientist working with carbon nanotubes, you might feel that the ribbon is easier. Especially because we really don't have to get all the way to 50-100 GPa. We can just taper it more, which will cost a lot more and have other problems, but we can design around those then.
You can, for instance, build a space elevator on the Moon out of, say, Kevlar. You'd still need a super-ultra reliable climber, though.
If it takes 6 months to get something into space it may end up being cheaper to use conventional methods especially if only one or two climbers can operate at a time.
First, it might be cheaper in terms of getting-to-orbit, but that's not the whole story. You don't need to design for stresses with a space elevator, for one. And second, keep in mind that once you climb to the end of the space elevator, you're moving very, very fast. You can let go of the cable and you'll have enough momentum to get to Jupiter.
Second, if it's too slow, there's an easy solution. Drop more elevators. The expensive part of the elevator is launching the first mass into space. Once it's up there, if you need to increase your capacity, it's a very small marginal cost.
There is absolutely no way that a space elevator wouldn't completely revolutionize space travel.
but is that more feasible than 62,000 miles of carbon nanotubing?
What do you mean by "feasible"? Possible? Yah, sure. No problem.
Do you mean "forseeably possible in the near future"? They probably both are.
No, the technology to beam power like that currently does not exist. Precursors to it definitely do. No, the technology to build a cable that strong currently does not exist, but precursors do. And no, the technology to build a climber that reliable, light, and low power doesn't exist either.
They're working on it. It's engineering. What do you want? Best way to build something is to try it, figure out what works, and try, try again.
Really? Are you sure? Can you build a bearing for a 20-cm wheel that will be able to turn 500 million times with zero chance of failure? And can you do it lightly? And in vacuum?
While we don't have the ribbon yet, we don't have the climber, and we don't have the power delivery system either. That's why it's called inventing. They're doing something that hasn't been done before.
And when you've got multiple independent difficult problems, you might as well work on all of them at once. Which they are doing.
Go and read the talks on building the climber at the last space elevator conference before you call it "trivial".
You don't need a counterweight. Counterweights are pretty much counterproductive - it's cheaper just to make the cable longer.
Oddly enough, we don't know how to get to near light speed. We do have significant engineering information on how to build a space elevator. Go out and read it. If you think it's as difficult as reaching near light speed, or moving an asteroid, you're crazy.
But who knows, maybe they do mean 62,000 miles? I thought the elevator's main purpose was to get things in and out of just the atmosphere, as to avoid all the problems with expensive and dangerous rocket launches and dangerous re-entries.
We don't use rocket to get above the atmosphere. Planes can pretty much do that. Balloons can (and regularly do) do that. That's the easy part.
We use rockets to get velocity, because you need a ridiculous velocity in order to actually orbit the Earth at a low height.
You do not, however, need a ridiculous velocity in order to orbit at a very, very high height. At geosynchronous orbit, you need no velocity, because you've already got the speed from the Earth's rotation.
So yes, they do mean 62,000 miles (100,000 km). And the benefits you get from a cable like that are insane. Costs/pound to launch things into space become negligible. Transit to the Moon becomes cheap and fast, because the end of the cable is actually moving faster than orbital velocity.
In fact, if you climbed all the way to the end of the cable, and let go with good timing, you'd end up past Jupiter (and on a direct trajectory, too, no mucking about in Lagrange points).
Yes, it's moderately insane. Yes, it's ridiculously difficult. But it would also end up being one of the biggest changes in human industry that has ever occurred. Space solar power plants beaming down power becomes feasible. Large-scale structures built in space become easy.
Plus, once we get the technology, we can build them on other planets as well. The Moon. Mars. It basically eliminates almost all of the serious difficulties of space flight.
Yah. That's the point. The cable goes to geosynchronous orbit.
Yes. That's long. But it's not as insane as you might think. The biggest concern is the tensile strength of the cable itself. Once (if, and it's a tough "if") that gets solved, it's just a matter of a really really big spool of cable.
Don't get me wrong. It's still moderately insane. It'll be #1 on the Discovery Channel's modern engineering marvels if it's completed - by a large margin. But it's not completely ridiculous insane.
Far from it. All of the components of a space elevator will be revolutionary, not just the ribbon. The climber's mechanical parts have to work flawlessly for about 100,000 km. The actual problem of gripping a cable isn't trivial, either. And it needs to be very low weight. Oh, and very low power. And just to make things even more fun, it'll need to work in vacuum as well.
If you read some of the papers on concerns for the climber at the space elevator conference, you realize that there's nothing easy about this. It's unsurprising that the climber is seeing the most progress first, but that first concern (perfect reliability over 100,000 km) will take a long time, so better to start now.
I mean, reading the article, it's obvious it's a parody.
I think they know.
lampoon (lm-pn') pronunciation
n.
1. A written attack ridiculing a person, group, or institution. See synonyms at caricature.
2. A light, good-humored satire.
However, the original article from ABC is, in fact, serious. It's also so ridiculously inaccurate, it's scary. Quoth I: "Predators are using Nintendo DS anywhere in the world. And it's going to be really hard to track down those individuals because of course, they're on a wireless network from a hotspot such as a coffee shop." which is totally false - as PictoChat only works DS-to-DS, which means the person they're talking to is a few feet away.
I dunno about you, but I think I can track a DS user who's a few feet away. I'm probably going to look for the guy holding a Nintendo DS who's not me.
But then again, this is why I don't watch local news. To paraphrase the Daily Show, "Is the media too sensationalist? Find out tonight, in our no-holds-barred expose that just might save your family's life."