Why don't we have an orbital ring?

[Zeropoint]

According to Wikipedia, an orbital ring would have the following very relevant characteristics:

* We could build one with the technology we have now. (in contrast to a space elevator, which would require material with a tensile strength greater than any material we can currently make)
* The cost of the project could be a mere 15 billion dollars, if we do it via "bootstrapping" with orbital facilities. (although the source of that figure looks a bit iffy)
* It would give us dirt-cheap access to space. (as in, cheap enough that ordinary working men and women could afford to send their car to space just to say they were driving a space car)

Now, there may be a bit of pie-in-the-sky in those figures, but we live in an era where multiple private individuals have that much money, let alone governments. Even if you assume the costs are much higher, the US spent about 1.7 Trillion, with a T, dollars on the Iraq war, to no practical benefit that I can see.

So . . . why the heck haven't we started on this already?

[NoXion]

Probably the same kind of reasons we don't have any supersonic passenger aircraft any more. The political will doesn't exist (looks like the ring would involve multiple countries thinking on the same page), and the blind idiot god of the market doesn't demand it badly enough.

It's not just technical limitations that can kill a project before it even starts.

[Sea Skimmer]

15 billion dollars is assuming that we already have orbital facilities to build it! And even then that figure is utterly suspect with no useful source, let alone any credible engineering calculations to back it up I see. The 31 trillion is no doubt wrong, but a lot more like the reality of what a system like this would cost to design, engineer and build. The US NASA budget is under 20 billion. Total global civilian space spending is perhaps double that figure. That's your answer. Nothing in space is cheap or easy.

Stupidly outlandish claims about how we can get cheap access to space are a dime a dozen.

[Adam Reynolds]

The most realistic way to get into space cheaply is the big dumb booster. A major reason that the rockets we use to get into space are so expensive is that we use so few of them. If we were to start producing a suite of rockets that get us to various points in the solar system, it would be the most effective way to cut prices.

Remember than in economics, average cost has quantity in the denominator. The more you build something, the cheaper it will be proportionally(in general). It's the same reason that it is often repeated that the B-2 bomber cost 2 billion. It's because only 20 were build. Had the USAF instead built the 200 they had originally intended, they would instead have a cost much closer to the 750 million that it took to make another.

[Zeropoint]

I stand corrected . . . if NASA's budget is 20 billion, then it's obvious that 15 billion for an orbital ring is not even remotely realistic.

I suppose if you amortize the cost of constructing an orbital ring over all the launches in a, say, twenty-year period, then the cost per launch might not compare favorably to that of a large-scale "big dumb booster" program. However, the marginal cost per kilogram to orbit would be much smaller, since you'd be getting things up there via elevator, not rocket. You could also cover the thing in solar panels and generate a large amount of electricity--without the environmental impact of current solar cell manufacturing, since you could do it in space with space resources.

I'd like to see us using the upcoming SLS program to build a manufacturing facility in space.

[FTeik]

IIRC, the current cost of sendind ONE kilogram into orbit are ~ € 20,000. Even if technological progress would allow a drop of costs by 90% with a budget of $ 15,000,000,000 (assuming parity between Euro and Dollar) you would only get 7,500,000 kilo or 7,500 tons into orbit. That is around 41 times the mass of the International Space Station, which is currently the largest object mankind has in orbit.

And even if we had orbital facilities to build such a ring, you would still have to transport the construction material up there.

[Jub]

And even if we had orbital facilities to build such a ring, you would still have to transport the construction material up there.

If we had orbital factories, we'd probably be better off mining the moon, capturing near earth objects, or hauling in materials from the asteroid belt.

[Zeropoint]

And even if we had orbital facilities to build such a ring, you would still have to transport the construction material up there.

Nah, you build the ring from materials that are ALREADY "up there".

[Lord Revan]

And even if we had orbital facilities to build such a ring, you would still have to transport the construction material up there.

Nah, you build the ring from materials that are ALREADY "up there".

as much junk as there is out there I'm not sure there's in fact enough useble material to build anything as big as an orbital ring

[Darth Tanner]

Nah, you build the ring from materials that are ALREADY "up there".

So you have all the cost of sending up automated mining, processing and construction robots then have to ferry half the asteroid belt into earth orbit.

And you wonder why we have not done this?

To summary...
A) we don't have the tech... in fact we don't have any of the tech we would need to do this. We can't build things in space, we can't ship vast amounts of materials in space, we can't mine materials in space
B) your cost estimate is laughably low to the extent you might as well said it would cost $15
C) moving that amount of material into earth orbit would take centuries with current and near future tech, and would expend vast amounts of material and fuel. Not to mention the risk of you missing and ramming a huge chunk of iron ore into the Earth!
D) Why exactly would we want to dedicate so much of Earths industry to a space vanity project?

Also from the wiki we would only get cheap access to space if the design included space elevators anyway!

[Elheru Aran]

And even if we had orbital facilities to build such a ring, you would still have to transport the construction material up there.

Nah, you build the ring from materials that are ALREADY "up there".

as much junk as there is out there I'm not sure there's in fact enough useble material to build anything as big as an orbital ring

Yeah, the majority of it is small bits and pieces of material that have been lost from the various launch vehicles, IIRC, and then most of it is just dead satellites... which are generally made to be light, hence they either aren't very large or don't use much material. I vaguely think one estimate I've heard was that if you collected all the orbital debris *and* functional satellites, it'd only cover a few square blocks, but that's all IIRC.

[Starglider]

A launch ramp (branded StarTram etc) is a much more practical and more cost effective idea, and we still haven't build one of those despite having the technology for 30 years or so.

[Zeropoint]

Sorry, I wasn't quite clear. By "up there" I meant resources on the moon, and asteroids.

As for why we'd want to do this, I should think that the cheap, easy, ubiquitous access to space would be a great boon for the global economy, and also for space exploration. It would also provide a place to mount very large areas of solar panels with minimal environmental impact.

As far as claims that we don't have the tech to do this, I would just references NASA's Asteroid Redirect Mission.

[Lord Revan]

about that NASA mission from the Wiki article you linked "potential future space mission" and "Still in the early stages of planning and development", it's planned to launch in 2020 and even that's a test mission to see if the concept will work at all and even that mission was estimated to cost 2.6 billion $.

the level of logistics an orbital ring you need is immense, so thinking we could use a method that's not even planned to be test until 5 years from now it's kind of silly.

[Sea Skimmer]

Also they want to use a 18.5 ton spacecraft to recover a 94 ton rock. That is not an inspiring mass ratio considering that the rock is useless unless you already have an orbital metal foundry for some large mass of material, and develop all the technology to make that work in zero gee which we most certainly don't right now. Refineries and foundries of all types heavily rely on a little thing called gravity to function. You would need to do smelting in a centrifuge to get the slag off in space.

The NASA proposal is far short of extracting resources from space. Addressing issues like this would cost immense amounts of money. It will have to be done some day but the up front cost is so high it is a tad unlikely anyone will even try until after low cost access to space is secured. That can be done a number of ways, hypersonic air launch for example will probably work within 15 years, but the only way to brute force it that will actually work is mass production of simple big dumb boosters. But that also requires the most money up front.

[SMJB]

If built by launching the necessary materials from Earth, the estimated cost for the system in 1980s money was around $31 trillion if launched using Shuttle-derived hardware,[4] whereas it could fall to $15 billion with bootstrapping, assuming a large orbital manufacturing facility is available to provide the initial 18,000 tonnes of steel, aluminium, and slag at a low cost,[5] and even lower with orbital rings around the moon.

Let's say these numbers are accurate. Where did this manufacturing facility come from? Why did we build it? If it was built specifically so that we could build the ring (yeah, good luck getting anyone with a free market economy to agree to that), it's price should be factored into the price tag for the ring itself.

If not, that implies that someone thought it made good economic sense to build a factory in orbit, presumably fed by mines on the moon and in the asteroid belt. This, in turn, implies that either launches are dirt cheap or that there is a market in space, presumably for something more than just a metric fuckton of satellites, which in turn implies that launches are dirt cheap. That being the case...why do we need the ring, again?

[Zeropoint]

That being the case...why do we need the ring, again?

Style.

You all have collectively made some good points, and I have to consider the possibility that maybe such a structure fits better at a later stage of technological development.

[Sky Captain]

Problem with many of non rocket space launch ideas is they require massive structures to be built in space. Especially orbital ring, it requires substantial structure to be built around whole Earth That is a lot of material. Space based manufacturing facility to extract and process that much material from asteorids or moon in reasonable time would be massive infrastructure project requiring dozens or more of heavy lift launches. Add to that R&D cost to develop large scale zero g mining and manufacturing tech.

Essentially you already need fairly cheap space launch capability to build such facility. Once mining and manufacturing infrastructure is built there would be much less need to lift heavy stuff into orbit so the requirement for cheap space launch would actually decrease since only people and high end tech components would go up.

If large scale space manufacturing were available i would say let's use that capability to fabricate orbital solar power stations - stuff that would make big difference here on Earth for billions of people.

[Zeropoint]

I could get behind a big fleet of giant solar powered space masers, too . . . even if they are only used for peaceful purposes.

[Sea Skimmer]

That's pointing towards another problem with these kind of structures, they'd require very comprehensive international agreements on permanent use of space, and space based weapons. The later being functionally needed to protect them from debris and space rocks. Discussion on this is severely hampered by the fact that the world made it a point to simply ignore the topic for so long. That had its own fair reasons, but they mostly just amounted to a mutual desire to save money.

[LaCroix]

Also, I'd believe such a ring would need to be anchored close to the equator to minimize problems of earth rotation, right?

This would mean a lot of states would be having that think literally hanging above their heads, should it ever have a failure, as well as the fact that it will cause trouble for conventional rocket space launches.

A launch loop would be much more feasible, as it could be built within a country.

[LaCroix]

ghetto edit:
Such a launch loop would also be the most realistic way to lift enough material for a ring, and then factories, and finally wharfs, fuel and material into orbit. Those will build asteroid capture vessels and start the interstellar mining business.

Starting from Lunar/asteroid mining to create a ring is a couple of orders of magnitude harder than this approach.

[K. A. Pital]

That is like asking why don't we have a permanent Moon base, except the Moon base was studied in much greater detail and much more feasible.

[jwl]

In terms of putting a factory in space, one way of making it commercially viable is to use it to build specialist materials that can only be made in zero-g. For example, high-transparency aerogels. Of course as the link says, you could solve the problem by making the processing time low enough to use parabolic flights, but that may not be the case with all materials, and for some functions you might need a facility larger than you could conceivably fit in a plane.

Then, in the future, perhaps the factories might be re-purposed to make more conventional materials from asteroids and such.

[Purple]

Will asteroid mining ever become really viable though? I have my doubts. The initial investment required is just way to huge even if you have the infrastructure in place. And the period you have to wait before payoff is too long. What happens if the mining company goes bankrupt before the mining ship arrives from its many years long trip? Or if it arrives back only to discover that the targeted asteroid is worth a fraction of our estimates? I don't foresee many companies or governments being willing to take that kind of risk.