[Kosh]

But sending the rockets there and back, even unmanned and with an empty hold, is still the most expensive part of the mission. Not only would you need enough fuel to get there, but you'd need to carry enough excess fuel to get back with a lot more weight added onto the ship. I really don't think that any of this is going to happen until current materials are near-expended and it happens to be cheaper for companies to go to the asteroids to mine than search the Earth for whatever scraps of precious materials are left. And at that point I'd bet that the world's economy would already be so crippled from thrashing that simply no one will be able to afford those missions aside from the richest nations and corperations.

It would not be one craft doing this. Going from Earth's surface to orbit is handled by a specialized craft, like the Skylon or some other launch system, then everything is handed off to another ship that is permenantly in space, where the extra weight of the fuel isn't such a big issue. This kind of thing isn't like anything we've ever attempted, largely because of really short sighted planning.

Fuel costs are surprisingly inexpensive. To give some sense of scale, the space shuttle used ~100 metric tons of liquid hydrogen and ~610 metric tons of liquid oxygen per launch. I've found a number of prices for liquid hydrogen, but I'll go with the upper one of $5.50 per kilo, so the total LH2 cost is $550,000 per launch. LOX prices are $1 per kilo, giving us a $610,000. Adding that up your fuel costs per launch of the shuttle (excluding the two solid boosters since I can't find pricing) comes out to $1.6 million, in other words a tiny fraction of the $450 million in total that NASA shells out for a flight. Where does the rest of it go? Can anyone say pork?

[Luis Dias]

Fuel is a minority of the price of any launch, but I think that this should be very easy to explain. To downplay the costs of a flight by comparing them to the fuel they spend is somewhat misleading, at best.

Having said that, and while appreciating the back and forth between you guys, I can't see much economic reasons for this space mineral industry to come about. First you need to create the need for these things en masse. I urge you to ponder more on what these reasons might be, i.e., why would a private company invest anything to be in space, considering the major costs and the fact that humankind is fine and dandy enough in this gravity well we call home.

[Polpolion]

It would not be one craft doing this. Going from Earth's surface to orbit is handled by a specialized craft, like the Skylon or some other launch system, then everything is handed off to another ship that is permenantly in space, where the extra weight of the fuel isn't such a big issue. This kind of thing isn't like anything we've ever attempted, largely because of really short sighted planning.

Fuel costs are surprisingly inexpensive. To give some sense of scale, the space shuttle used ~100 metric tons of liquid hydrogen and ~610 metric tons of liquid oxygen per launch. I've found a number of prices for liquid hydrogen, but I'll go with the upper one of $5.50 per kilo, so the total LH2 cost is $550,000 per launch. LOX prices are $1 per kilo, giving us a $610,000. Adding that up your fuel costs per launch of the shuttle (excluding the two solid boosters since I can't find pricing) comes out to $1.6 million, in other words a tiny fraction of the $450 million in total that NASA shells out for a flight. Where does the rest of it go? Can anyone say pork?

The Shuttle orbiter using a combination of LOX/LH2 in its external tank. How on Earth does that lead to pork, or do you honestly think that the people that were working on the shuttle program added both just for kicks? IIRC they used a combination because just LOX wasn't the safest thing to use, but I'm not totally sure about that. I do know, however, that the SABRE enginges on the Skylon haven't even been prototyped in space yet whereas the engines on the shuttle have been in service for over 30 years, and given that they're phasing out the shuttles calling their use pork is fairly absurd. Pork doesn't work that way.

edit: my poosts are borky partially because I can't read and partially because elinks makes things complicated. maybe I should use a real web browser.

edit2: christ, who am I even quoting? all I remember is pork and fuel and I don't want to scroll up to check, so feel free to ignore everything in this post. So: pork barrel spending is just money being spent by congress that's generally "overlooked" when it's snuck onto a bill here or there, that no one really opposes just because of how mundane it is, but isn't really important beyond the fact that it garners support for the congressman in his/her constituency. High expense in shuttle launches isn't pork, it's just high expense.

edit3: damn elinks, can't modify posts without quitting once for some reason and scrolling in text boxes is a PITA. I'll stop editing after this one, promise. Using multiple spacecraft for a single mission like this adds lots of overhead for such a simple task. In the future this might be feasable when there is a larger selection of multipurpose craft available for use, but come to think of it midedit I realized that what you could probably do is assume you can get an asteroid in a near geosync orbit or so you could have one launch with a craft to get equipment there, mine stuff, then put it in a large gun and shoot it back to earth. You'd be shooting into the Earth's gravity well from a relatively small asteroid and you wouldn't need to bother with people or spaceships, just put it in a heat shielded box with a parachute and it'll be fine.

[newman]

And yet NASA was perfectly willing to shell out a billion to launch the Ares 1 while SpaceX was able to launch a rocket with the same amount of payload capacity for $50 million. NASA routinely goes over budget on nearly everything precisely because they are fundementally inefficient, with a bloated bureaucracy and highly protected jobs. One of the biggest reasons the shuttle lasted as long as it did was because it was viewed more as a pork barrel earmark rather than an asset, each shuttle took several thousand people for each orbiter just to keep it airworthy (for comparison the Skylon is intended to have a support crew of just 200).

Which pretty much means we agree on this point. Private sector hates negative profit more than governments and will be more efficient by definition.

Ah but mines crank out continual streams of said expensive ores. Once the machinary is up there it stays there, forever. Once the rock you're currently mining is depleted, you move it to another one. The machinery is a one time investment and people get rotated and resupplied on each trip. But you're also forgetting something important, what happens to the other metals? They stay in space where they will be used to build the infrastructure in space needed for future expansion. That greatly reduces the cost of space construction allowing for great expansion beyond the initial infrastructure you claim wont happen for centuries.

Machines a one time investment? Mining machines? You're kidding, right? I actually work for a company that, among other things, produces machines used in deep mining. The strains put on these rigs are enormous and even with the best quality control you have a constant need for maintenance. When you drill something, zero g or not, you will produce three things in excess; friction, heat, and fine dust. None of these play nice with your machines. Your drills will slowly dull no matter what super material they're from. Fine dust will catch onto your machine's parts no matter how well you protect them. Heat will do it's thing making sure the degradation is faster. You will have to isolate your constantly drained batteries well and replace them every now and then. And I haven't even gone in the technical challenges of near zero-g gravity environment mining, unknown (so far) tectonic stability of these rocks (you know, a part of a rock breaking off and floating away with your drill attached to it isn't nice) or the fact you have no Earth's magnetosphere protecting your equipment's electronics from solar winds and enormous amounts of radiation our Sun churns out. Mining machines mean a constant amount of maintenance even on Earth. In space, the needs and costs of that maintenance would rise exponentially. And we had real technical challenges just fixing the Hubble for the last time which is right here above us, not in some asteroid field over 2 AU away that took our latest probe over 5 years to reach. Even if that wasn't the case the costs of doing this would be astronomical if run from Earth. With the constant need for maintenance we're talking about sending manned missions for doing this, sending new machines to replace old ones each time they break, or having some sort of automated repair droids that would cost another infinite amount of money, r&d of tech we really don't have yet, and introduce even more parts to maintain in an already convoluted equation.
Or you can go mine your aluminum on Earth and have it shipped over on trucks/ships at a fraction of the cost.

What you're proposing would only make sense if we already had an extensive presence at least in the inner solar system. Otherwise, I don't think you realize just what sort of technical difficulties and engineering challenges you'd run into.

The process would need to work like this;

- cost effective, large scale way of getting to the orbit and beyond developed (don't have it);
- Mankind starts setting up in space. Research outposts crop up on the moon and Mars, following by larger and larger settlements appearing around them.
- We build orbital shipyards to facilitate interplanetary - only travel as we go further and further.
- To support these, we build mines on asteroids and low gravity planetoids as a cheaper way of getting resources that essentially stay in space while mined.

And not like this:

- I want us to be in space so orbital mines, now. We had some rejected space propulsion concepts in the 70's and 80's so surely that means we're technically able to it. In fact let's just use nuclear pulse propulsion or nuclear rockets and launch right from LEO. Getting a bunch of hydrogen bombs detonated over people's heads every time we need to go mine some rock will get approved like a snap.
- Let's find a way to use these mines now! It has to be cost effective, right? It's space, it's cool, I want it now.

Don't get me wrong I want it now too. Fact of the matter is if it was actually cost effective we'd be out there now. And sadly neither one of us will be skiing on Mars for vacations. I don't like it any better than you do but you can't blame the politicians for that. You can blame them for not investing enough in science, new propulsion technologies and space exploration. You can blame them for cutting NASA's budget yet again. You can blame them for canning the shuttle while having no replacement in sight. You can blame them from essentially giving up on putting boots on Martian ground, meaning rather low chances of seeing man on Mars during our lifetimes.
You can't blame them for not having colonized the inner solar system and not setting mines on asteroids. A lot of things need to happen before we get there. Problem is, we're not doing them. As for the private sector, when they smell money in a more serious space presence, with the technical means to make it profitable, don't worry it'll happen. The fact it hasn't so far speaks for itself.

[Thaeris]

It would be great to have another age of philanthropy (for the sciences specifically). Now you just need to get Bill gates to set aside a quarter of his net worth, find a dedicated, composite research and development group, and you'll be able to do some wonderful things for space. I for one would do that if I had 40 billion lying around...

[newman]

I for one would do that if I had 40 billion lying around...

Same here, in a heartbeat. Though I'm not sure how many people would be comfortable traversing interplanetary distances in a ship Bill Gates had a hand in

[Luis Dias]

paul allen, a co-founder of MS, is actually a very big sponsor of space related crazyness.

[jr2]

Hmm, about the space elevator... I have an idea that probably wouldn't work... Would it put less strain on the cable if you had a counterweight ever so often attached in-line to the cable?  Or does it make no difference?  I think probably no difference because the asteroid's mass must be tethered in orbit, so x amount of pressure must be applied to counter it, so somewhere on the cable there will be that strain on the cable.  However, it would reduce the strain on the anchor at ground level, perhaps to the point that there is no strain at all and it's more of a positional anchor (tying the line to a specific location on the globe) than a orbital anchor (keeping it from flying out of orbit).

[Unknown Target]

Thoughts?

By the way, to answer your question, no. The "Space Age" as it was coined ended long ago; the Space Shuttle happened to be what was left at the end. That age ended - IMO, if anything the retirement of the Shuttle signifies the real end of it. We are no longer living in that "age". We will probably still go to space, but I think it will be called something else.

[Polpolion]

Hmm, about the space elevator... I have an idea that probably wouldn't work... Would it put less strain on the cable if you had a counterweight ever so often attached in-line to the cable?  Or does it make no difference?  I think probably no difference because the asteroid's mass must be tethered in orbit, so x amount of pressure must be applied to counter it, so somewhere on the cable there will be that strain on the cable.  However, it would reduce the strain on the anchor at ground level, perhaps to the point that there is no strain at all and it's more of a positional anchor (tying the line to a specific location on the globe) than a orbital anchor (keeping it from flying out of orbit).

Hell, just using two cables instead of one should halve the tension required on each. But this seems too simple, I don't know why no one else would've thought about it.

[Unknown Target]

Isn't that the concept behind a woven rope? (Such as in a high strength rope made of steel?)

[Polpolion]

You'd think so. So you'd need about 150 strands of Carbon Steel 1090 to get ~130GPa. But looking here there are plenty of other materials that have greater tensile strengths.

[redsniper]

Yeah, guys, srsly. You're not going to use the "hardest grade of steel" to make a tether like this. Generally, the harder a steel is (or just about any material really), the more brittle it is, and you definitely don't want to make a brittle tether. Secondly, you're all squabbling about the tensile strength when you should be comparing yield strength. I mean do you really want your 36 kilokilometer long tether going into plastic deformation? Really?

But what do I know, I'm just a practicing mechanical engineer.

EDIT: Although you would use tensile strength in the case of brittle materials. So I guess if you found some brittle unobtainium that was far and away stronger than needed, you could safely use that for a tether.... maybe...

[The E]

Hmm, about the space elevator... I have an idea that probably wouldn't work... Would it put less strain on the cable if you had a counterweight ever so often attached in-line to the cable?  Or does it make no difference?  I think probably no difference because the asteroid's mass must be tethered in orbit, so x amount of pressure must be applied to counter it, so somewhere on the cable there will be that strain on the cable.  However, it would reduce the strain on the anchor at ground level, perhaps to the point that there is no strain at all and it's more of a positional anchor (tying the line to a specific location on the globe) than a orbital anchor (keeping it from flying out of orbit).

How big would the counterweight have to be? Also, a counterweight that's woven into the cable itself isn't so much a counterweight as a way of increasing the cable's mass.

Also, before continuing this discussion, I would advise you to read this primer on the subject.

[NGTM-1R]

I think everyone advocating private development has lost the plot. The reason the government has subsidized space-related ventures, the reason we have any at all, is because it's not cost-effective to go there and do stuff privately.

Well, it will be with new technology right?

Who's going to develop new technology for a field nobody's interested in currently? The reason we have, and still need, the government involved in space travel in a major way is so somebody's pushing the stuff forward. The proposed future of glorious private space exploitation isn't going to come unless somebody makes the building blocks first, and private industry isn't going to be the people who do it.

[Unknown Target]

Well, I mean also the original idea of government was that it was a public thing, it was for everyone. With private interests controlling space travel, they can restrict it as they see fit, and can't be held accountable to anyone for it, really.

[Scotty]

The above post reminds me strongly of a "ZOMG CORPORATIONS ARE TEH EVULS" post.  They exist to make money.  If space makes money, they'll go for it.  If it doesn't, they won't.  There's no such thing as them "restricting" anything, espectially not just for teh lulz.

[Polpolion]

The above post reminds me strongly of a "ZOMG CORPORATIONS ARE TEH EVULS" post.  They exist to make money.  If space makes money, they'll go for it.  If it doesn't, they won't.  There's no such thing as them "restricting" anything, espectially not just for teh lulz.

Tell that to Microsoft and Apple.

[Scotty]

Congratulations!  You found the two least applicable exceptions.  Software is an entirely different can of worms than something like space exploration.

Now find a decent reason for any corporation to restrict said space exploration and or usage.

[Unknown Target]

Congratulations!  You found the two least applicable exceptions.  Software is an entirely different can of worms than something like space exploration.

Armadillo Aerospace?

Now find a decent reason for any corporation to restrict said space exploration and or usage.

Hm...I really can't think of one, to be honest. I'd honestly prefer a mix of public/private for a lot of things, and for space travel I think it would help as well. They're both part of a single society; I think private assets should be thought of with a mind towards making things free and public should be thought of with a mind towards making them sustainable. The two are not mutually exclusive, of course.