Space Elevators Going Up

MikShapi writes "CBC is running a new piece on the Space Elevator. Nothing dramatically new, as we're all still waiting for one of the many Carbon Nanotube research centers to announce they reached the famous 100GPa red line from page 10 of the NIAC Phase 2 Report, thus obtaining 'unobtainium' [pun intended], the material necessary to build the Elevator. The report predicts this will happen during the course of the next two years or so. It's then that the fun really starts - A REAL all-out space race, open to everyone with will and a national budget, winner probably getting to own space [read last paragraph]. In the meanwhile, we can all spread the word, discuss, debate and brainstorm every nook and cranny of the program here on Slashdot, and give Edwards a shoulder by giving the program every bit of mass-exposure we can."

Comments

Doubtfull

[Smitedogg]

A REAL all-out space race, open to everyone with will and a national budget, winner probably getting to own space

I predict that there will not be a space race, because the cost-benefit isn't acceptable yet. If this technology is only 2 years away (doubtful again), then there would be massive funding to accelerate the program if there was enough interest. Lack of interest now means that there is probably not going to be much interest when the nanotubes arrive.

Dogg

Re:Doubtfull

[houstonbofh]

There will be funding just as soon as it looks like someone else could make it. No one will want to be the president who "Lost space to the Chinese." Embarrassment is a powerful motivator.

Re:Doubtfull

[AndroidCat]

And it would be nice to do a few trials first. Make a bridge out of it, put a few miles of it up in space. See how the stuff lasts over a couple years under various loads and conditions. A space elevator is a very messy thing to have an "oops" with.

Re:Doubtfull

[Jerf]

If exponential growth predictions hold true, and the "first entity" locked out others from use, then the "first entity" would be a "winner" simply due to taking off too rapidly for others to feasibly catch up. That doesn't make the other entities "losers", except in relative terms; they may always be four years behind but that four years may represent a factor of, oh, as long as we're being fanciful let's say 50.

However, I think there's a majorly false claim in there, which is that the first owner will lock out everyone else. Obviously, the first order of business when you have a space elevator is to put up more of them, and for a while they may indeed have a monopoly. But given the resources still available on Earth, someone will eventually tender an offer for a fully-completed cable that the first entity can't refuse; no matter how valuable the cable, it is possible to pay the owner off today with $X dollars, which the first entity will (correctly) perceive is more valuable to have it in liquid form, available to then invest back into other things. That price may be sky-high, pun semi-intended, but there are people on Earth who will be able to afford it.

By buying a completed cable, they can jump-start themselves up, and as more and more entities do this, it'll start looking more even. While the first mover will have a true advantage that may last a very long time, I don't see a situation where they maintain a 20x advantage over everybody in perpetuity; the value proposition of liquidating one of the cables is just too appealing.

This assumes a capitalistic owner of the first tether, and if the US gets there, the world can for once be glad that we see everything in terms of dollars, sooner or later, because that means that we will indeed have our price (though in the truest capitalistic tradition, it will be all the traffic can bear!). If it's not the US, well, it depends on who gets there first, but even so, it would take a very strong government to turn down the offers it would get... some of which are quite likely to be of the "offer you can't refuse" variety. ("Dear China: We still have nukes. Sincerely, All Nuclear-Capable Countries.") I still can't imagine a plausible long-term scenario where somebody maintains a massive, multiplicitave lead indefinately, though again, serious short- and medium-term advantage do accrue to them. (If nothing else, they'll need to draw on international capital to invest in space itself.)

Re:Doubtfull

[jafiwam]

If you mean "pretty much in the same place" as in "on the equator" then sure.

Though the orbit is geosynch, it isn't because of the distance of the center of mass of the thing. It's the distance of the center of mass of the thing while tied to the ground.

Let it go, and it gets an elipitcal orbit that is NOT geosynch, and the thing comes back from it's elipical orbit somewhere else on the same latitude.

Next, you are also assuming the thing does not have any "springyness" and bunch up on itself.

Not a trivial problem.

I bet you a taco dinner that if the cable gets cut on the ground it never comes back in a way that can be used.

What does human advancement require?

[ObviousGuy]

Whenever a space story is brought up, some person always brings up the argument that perhaps we should spend money on the poor instead of a useless space elevator (or whatever the space story du jour is). I don't think they are arguing correctly. Space is just as important to human advancement as feeding the hungry, curing chronic diseases, and providing a livable environment is. I don't think you can order these in importance, they are all important.

But they go hand in hand with each other. Unless we truly believe Matthew 5:5, that the weak will inherit the Earth, it will take a worldwide view of humanity to move us to the next stage of human advancement which is the eventual separation of humans from the Earth and into the galaxy. We can go this alone, leaving the world's poor to their own devices, while the space superpowers leave them behind. However, when the day comes that certain small groups of humanity take to the heavens leaving this world and venturing off into the depths of space, how will history treat those of us living now who failed to hold the hands of those unable to stand with us as we raised humanity to new heights?

The space elevator is a great achievement. Hopefully we will begin to have a true space-based space program that is not dependent upon sending rockets to the space station. This would be the largest step in the path to Earth separation since the first manned space programs.

However, taking steps only with our strongest leg means we are still limping. We must strengthen all our limbs as members of the human family, IMO.

Re:What does human advancement require?

[1u3hr]

Whenever a space story is brought up, some person always brings up the argument that perhaps we should spend money on the poor instead of a useless space elevator

I'm sure that more is spent on any one of: cosmetics, fizzy drinks, cigarettes, SUVs, cocaine. If you're just talking about govt expenditure; at least 100 times as much is spent on the military.

If access to space is much cheaper, the benefits to the world will be immense; though it'll take a few decades. Even back in the 70s when O'Neill advocated space colonies in the L5 orbits it was possible to make a case. With a much cheaper launch method it becomes compelling.

Re:What does human advancement require?

[Goldsmith]

Every stage of major social advancement throughout history has come as a result of increasing opportunity.

Were it not for exploration and technological advancement, we would almost certainly still be living as serfs to some fuedal lord.

When the US was founded as a large republic, many people thought it would never make it. The success of representative government has improved the lot of many people, and arguably, the poor of the entire world.

Now, we are all at a standstill. There is no place for people to go who seek to try something new. There are no experimental governments anymore, and there are no nation-wide experimental social systems. Individuals or small groups fight to improve the world, but there's nothing to be done against the inertia of the status quo. Things will improve, but slowly.

Space offers that opportunity we need. Naive people see space as a playground for the rich. If we're going to have a playground, we're going to need to build it. The first people who will go permanantly up in a space elevator will be construction workers and engineers.

When you take into account the resources available, and what it means for an end to mining and power production on earth, you have a pretty powerfull vision.

It's remarkably short sighted to argue against taking ALL of humanity a step foward because we're not all on equal footing. We NEED to take this step foward, DESPERATELY, in order to help solve poverty, exploitation and many other ills in the world.

Re:What does human advancement require?

[NoData]

We NEED to take this step foward, DESPERATELY, in order to help solve poverty, exploitation and many other ills in the world.

With all due respect, I call bullshit. Your arguments and the parent post's arguments are simply so much sentimental claptrap.

There's so much clamor for 'intellectual honesty' in the current political climate, let's start here.

Let's call a spade a spade. Space exploration is worthwhile because we, as a society, have decided that the enrichment of human knowledge is a virtue per se. Knowledge for the sake of knowledge. Human endeavor. It needs no other rationalization.

To say that space exploration is worthwhile because of unrealized, indeterminate side effects that are not the goal or intention of the pursuit, but held up, nevertheless, as some sort of social promisory note is just sophistic rhetoric. Tomorrow, I'll go tell the homeless guy down the street the good news: "Worry not, dear poor person, for we are building a space elevator that will elevate the dignity of all humankind, and so too shall your station rise!" Yes, and then I'll go tell the patients in the oncology ward that we shall cure cancer by building flying cars, for surely some modicum of the technology needed to build a flying car will make cancer fly from the body as well.

Here's the thing: Multiple fronts. Society proceeds on multiple fronts. We don't stop space exploration because we have sick and poor people. We don't stop researching epilepsy because we have diabetes, stop researching diabetes because we have AIDS, stop researching AIDS because we have cancer, stop researching cancer because middle aged men have erectile dysfunction. What we DO do (giggle) is engage in a torturous debate in resource allocation. In terms of real life application, space exploration is an incredibly expensive, high risk investment with a possibly high payoff potential on a very far time horizon. But in the short term, we learn a lot about how the world works. This does improve the human condition in some abstract sense, but to say that it is a necessary step to curing some of our pressing social ills is disingenuous. The way to address our pressing social ills is to, you know, address our pressing social ills. We just have to figure out how to do that in a responsible way and still leave enough money over for the purer, less immediately tangible pursuits that we collectively value. Doing this factor analysis well is the hallmark of good government.

Re:Uh..

[cnkeller]

Isnt that um, impossible given our orbits in relation to each other?

Two different elevators guy. One on mars and another on earth. For lauching payloads from both planets. We are going to eventually have to travel home from mars....

Re:Bouyant cables!

[Anonymous Coward]

Bouyant cables, even in the best case, can't get you out of the atmosphere, so maybe 1000 km on the top side. The space cable has to reach geostationary orbit, some 35,785 km out. You lose :)

Hmm

[ShooterNeo]

One question : the basic plan involves transmitting power through microwaves or laser light, enough electric power to provide the kinetic energy difference to actually put a vehicle in orbit. Why not skip the development of unobtainium and skip trying to put a super long and heavy cable in orbit? Just build the power laser facility 10 times over, and build spacecraft that use a block of inert propellant, heated to millions of degrees celcius from pulses from the laser and pulsed such that the shockwave is a planer wave coming away from the spacecraft. So no nozzles, no rocket engines, no pumps, no chemicals, no fuel, no explosives...all the stuff that make spacecraft expensive and dangerous. Just a block of cheapo rock and a spacecraft built like a cheap copy of an Apollo capsule made by the Russians. Would be safer as well, since in-orbit is pretty safe (there are patches to plug small holes), launches no longer can blow up, and reentry is much simpler and less error prone that with a space shuttle. Finally, that kind of laser would make a rather fine weapon, and would help out military applications as well (so could get some of the funds from the U.S. military budget)

Do your elevator pitch

[btempleton]

At least if you found yourself caught with a VC in this elevator, you would finally have time to really pitch your business plan.

On a serious note, they predict it would be hit, if not moved, by a large space object around once a year. They think they can spot these objects and move it as needed. But what about smaller objects. How much damage will they do? How easily can they be detected? How often will they hit?

And worse, what about deliberately launched smaller objects, radar-invisible small objects fired by a nation that doesn't want another nation to own space.

Ridiculous, but plausible...

[Goonie]

the 100 GPa number sounds ridiculous.

For context: the most common type of structural steel currently used has a yield strength of 350 Mpa. 100 GPa is 285 times stronger.

Yes, it sounds outrageous, but it's theoretically possible to do this with nanotubes, apparently. As I understand it, nobody has actually demonstrated a macroscopic piece of nanotube composite with this kind of strength though.

To suggest that this can be achieved in a couple of years sounds silly to me, considering whatever material used would a lengthy term of testing and a proven track record before sinking billions of dollars into it.

True, but the things made possible with such a material would surely attract billions of dollars worth of R&D. Can you imagine what it could do for things like aircraft design?

Re:Ridiculous, but plausible...

[Alan Shield]

Can you imagine what it could do for things like aircraft design?

General Products Hull's here we come!

Re:Conservation of angular momentum is the fatal f

[The Master Control P]

Not speaking as a physics grad here, and possibly talking out my ass, but I was under the impression that the space end of the tether would be a little outside the balance point, such that (if not for the cable holding it down) it would continually try to fly off into space. Thus, when it's energy was sapped by the launch of a new spacecraft, it would in turn sap the rotational energy of earth to return to it's highest possible orbit.

There ain't no free ride into space: The elevator will simply replace violently exothermic chemicals with the slow sapping of earth's rotational energy.

Re:My prediction

[mcrbids]

It'll be at least a century before one of these things actually do anything useful.

What's sad is that it may well take that long.

However, the best thing we could do to promote the sky elevator is to develop and build nonotube-based structures here on Earth.

For example, if you were to rebuild the Golden-gate bridge in San Fransisco with nano-tube cables instead of steel cables, would they even be visible from the shore?

An impressive, previously infeasible structure, such as a bridge spanning the entrance to the Mediteranean, or across the English Channel would do much to get everybody used to the idea that something like this could, in fact, be done.

Also, projects like this would give us opportunities to answer questions about its durability, relability and safety in a large number of circumstances.

Building a space elevator with nanotubes as the first project is fundamentally stupid. Build something more reasonable first!

Cost

[Moderation abuser]

I predict that a space elevator will make the cost of the lunar landings look like peanuts. I very much doubt it'll happen in our lifetimes.

NASA is the reason space is expensive. Companies like Starchaser and Scaled Composites are the ones who will make space cheaper and will "own space".

Cable propagation lessons from the launch loop

[klic]

I've fiddled with the math for these kinds of things for decades on an old idea called the "launch loop". The dynamics of long tapered cables are not impossible, but they are nasty. Very long cables are not like a stout rope to a fixed point nearby, they are more like reaction mass that vibrates. Think "Tacoma Narrows Bridge", which fell down because 1930's engineers did not take their differential equations up to 7th order.

As a climber goes up, the surface anchoring system must pay out more cable to fill in the less tensioned region under the climber, faster and faster as the climber accelerates up the cable, proportional to the speed of the vehicle, total acceleration (including gravity) and inversely proportional to the mass per meter and the square of the propagation velocity of the material.

This is continuously changing, so forces and velocities at the surface are changing also. The problem is, this is an underconstrained and essentially undamped end-terminated system - as the cable gets very long, you develop big standing wave complexes with only two points (surface and top anchor) to remove or store the energy. Keeping the standing waves from building up is difficult, but not impossible. However, it does add an additional constraint on launch rate; you have to spend a lot of time damping out the waves, even granting that these people are more clever than I am at modelling and removing this energy.

Tapering of the cables, necessary even with magic nanotube unobtainium, makes the math even more "exciting", with the additional constraint that the through-atmosphere sections, along with the sections that dip into the atmosphere during wave motion, have to be thoroughly protected against atmospheric degradation (hint: C + O2 -> CO2 ). The portions of the system below the Van Allen belt have to be armored against atomic oxygen damage. Atomic oxygen will burn off the leading edge of ISS at rates approaching a millimeter per decade; the space elevator will be stationary in the gas field, but there are still a lot of fast moving oxygen atoms up to, and through, the radiation belt.

All motor driven systems have limits to their power-to-weight ratio. To get to GEO, we have to add about 60MJ/kg. If we take 33 hours to do so, we need to move an average of 500 watts per kg (total climber weight) through the (photovoltaic or microwave) energy collectors, motors, rollers, etc. For comparison, a 1500 kg sports car with a 300 horsepower gasoline engine uses 150 watts per kg. However, that underestimates the problem. Most of the energy will be added at the beginning of the climb, during the first 10% of the travel distance, as the climber leaves the depths of the gravity well, so expect thousands of kilowatts per kilogram in the power train during this phase. If there are unexpected variations in the power, the change in climbing acceleration will add more ripples to the cable.

I tried to avoid these problems with the launch loop (see URL below) by keeping the altitude under 100 km and the motors on the surface. Even over those "short" distances, cable propagation issues are problematic. Funny/bad things like lightning, ice buildup, fractally gusty winds, and jittery payload forces require special attention, and all reduce the capacity of the anchoring and stability cables. Everything above the atmosphere is exposed to a steady rain of the garbage that your launch system has accumulated in orbit (it all comes down, eventually). Reentry systems for human payloads (in case of failure) add weight. Problems, problems.

At the end of the day, though, the killer issue is lack of demand. The launch loop, with about the price as a space elevator (+/- 3dB) and using materials and technologies we have had for two decades, can put 80 tonnes of payload into orbit *per hour*, for less than $10/kg. Unfortunately, nobody wants that much mass in orbit, even at that miniscule price. Perhaps "if you build it, they will come", or perhaps you end up with another white elephant lik

Only $5 billion? $500 billion maybe.

[Moderation abuser]

The channel tunnel cost $21 billion and that's just a couple of big holes in the ground. The cost is going to have to be amortized across generations of users. I do agree with your point though.

More people fly from the UK to the continent these days because it's much cheaper, faster and more flexible.