[Kosh]

earn how orbital mechanics work.

Orbital mechanics were patented by Boeing.

[Nuke]

no they only patented a particular maneuver, and you're in the wrong thread.

as for nuke engines, their all cool and what not, but there are hundreds if not thousands of different engine and thruster systems out there on the drawing boards in labs world wide. the main issue has been the power supply. the best space worthy nuclear power plants we have today still dont produce enough power to run many of those thruster designs. nuclear engines do get around that because the energy source is heat rather than electricity. i see nuclear engines as just an interim solution, a stepping stone between chemical and some uber powerful super engine (not quite warp drive).

[S-99]

Very much true. Nuclear engines are an upgrade to current chemical rockets, but not a different engine type. They both function pretty similarly, it's just that nuclear puts out more thrust and consumes half the fuel compared to a chemical rocket (it'd be great for going to mars). Any other mission that happens around earth orbit and the moon, those craft could employ a fuel tank that's half the size or just stick with chemical rockets (chemical rockets are great for local space, not deep space, nuclear could let local earth missions have a fuel tank half the size and output more thrust and carry less weight). But, yeah, nuclear rockets is not really an upgrade over chemical rockets, nuclear rockets i consider to be chemical rocket system 2.0, because it still uses chemical fuel and it's a rocket. Just different fuel and heating process. Really it just seems like a chemical rocket with more power and gas mileage. Going nuclear thrust is going to be like buying a car today and selling you're old muscle car.

[Kosh]

I really think it is a shame that we didn't listen to von Braun's ideas about having a permenant presence in space way back when. We only went to the moon in the 60's because the Soviets were talking about going there and we just HAD to get there first. After we went there, popular support for that kind of thing fizzled pretty quickly. And now, we suddenly started talking about going back AFTER China announced its intention to go to the moon.

In any event, Russia is intent on building what amounts to an orbital shipyard so that way their spacecraft size and range wont be so limited. Frankly this is what we should have done years ago, but apparently couldn't be bothered. Good for them for having the vision we lack.

[Black Wolf]

Metal depletion has been going on for decades. We've had enough copper for twenty years for the last 40 or 50 years. We just keep moving onto lower and lower grade ore and finding more in previously underexplored regions. There're vast deposits under the sea, hell - there're enough metal ions in the seawater itself to keep us going for millenia if we could extract them cost effectively. While certain highly specific, highly useful minor elements might become scarce (I'm thinking stuff like tantalum, Some of the REEs and PGMs) we're not going to run out of copper, especially as extraction technology gets better and people start (eventually) mining landfills and the like).[/color]

[Flipside]

I'm thinking of putting two huge electrodes at either end of the Mediterranean and creating the worlds biggest electrolysis tank, that should help

[Kosh]

Metal depletion has been going on for decades. We've had enough copper for twenty years for the last 40 or 50 years. We just keep moving onto lower and lower grade ore and finding more in previously underexplored regions. There're vast deposits under the sea, hell - there're enough metal ions in the seawater itself to keep us going for millenia if we could extract them cost effectively. While certain highly specific, highly useful minor elements might become scarce (I'm thinking stuff like tantalum, Some of the REEs and PGMs) we're not going to run out of copper, especially as extraction technology gets better and people start (eventually) mining landfills and the like).[/color]

I have a question for you: How much in the way of world wide Uranium reserves do you think we have? I've heard things like if we built several thousand nucelar reactors that it would burn up all the Uranium in a decade or two. Any truth to that?

[Fearless Leader]

I have a question for you: How much in the way of world wide Uranium reserves do you think we have? I've heard things like if we built several thousand nucelar reactors that it would burn up all the Uranium in a decade or two. Any truth to that?

The real question is, who said that, and how do they know?

[Black Wolf]

Not really, thanks to breeders, and as I said before, sea water extraction. There's a really good article I read on it online somewhere but I can't find it anywhere at the moment. Here's a good one though that explains some of the economics behind it:

http://www.theoildrum.com/node/2472

As for Uranium in the current situation... well, based only on the Australian situation, which is all I have any personal knowledge of (and which, ultimately, is what matters the most since we have nearly 2/3rds of the worlds extractable uranium) I suspect we coiuld increase uranioum production a lot quicker than the world could produce the reactors to consume it. Uranium mining is extremely limited in Australia by the government's three mines policy, but Uranium exploration is a totally different thing. It's growing in tandem with the price increases as the former weapons stock gets used up. The result of this is that Australia has access to dozens of proven, mine ready uranium resources, some of which (like the calcrete deposits at Yeelirie) are exceptionally easy to access.

The net result is, as a nation, we're poised to pick up a fairly significant increase in global uranium demand. However, people're also acutely aware of the long term supply problems, and I think the whole peak oil thing at the moment will probably prevent governments from getting over reliant on a restricted energy source again, and thus the development and establishment of breeders is pretty much inevitable. While there's a pickup delay in getting fuel from breeders once they're turned on, I think the world could cover it. And yeah, there's always oceanic extraction if it can be made cost effective (which is inevitable if we start getting dependent on nuclear power - that link explains a lot of that).

[Topgun]

just where is the metal going? it is still on earth, right?

[Flipside]

Probably a fair percentage is in Land-fill sites etc, the computer you are using right now has a moderate amount of copper involved in its construction for example, but not enough to make it cost-efficient to recycle it.

[redsniper]

Yet.

[S-99]

Nuclear power. Good stuff

[Kosh]

and I think the whole peak oil thing at the moment

Funny you should mention that, CIBC put out an article the other day warning of $200+ per barrel oil by 2012.

Actually in the US a lot of people (in the general population and in government) are still in denial about peak oil.

[S-99]

Gas is annoying. E85 is really ****ty, bio-diesel is a good one, and people are still looking for a way to more easily procure hydrogen. It'll be nice once that hydrogen thing gets figured out.

[Black Wolf]

just where is the metal going? it is still on earth, right?

The vast majority of it, yeah. The problem is finding it in economic concentrations. Best way to think about it is in terms of examples. Ironis a good one. Humans have been smelting iron, for, what, a couple of thousand years? The first iron came from the easiest to access, higest grade ore deposits around, because there was plenty of it and nobody had used up those deposits. As technology got better, it became easier to extract iron from lower grade or unusually hosted sources. Eventually, the modern economic controls developed, and as demand increased, the price increased, and we moved on to lower grade iron deposits, which became economically viable to mine thanks to the relatively high price of iron.

The problem is twofold - number one is that, as Flip alluded to, we're not very careful with our resources, and a lot of metals get lost to landfill, or dumped in the oceans or simply rust away to nothing and disperse through the air. The second problem is that, sooner or later, we're going to run out of ore deposits that are economically viable to mine (either because ore deposits of a suitably high grade simply no longer exist, or because the price required to make them economic puts the commodity out of reach of the market. Disregarding the stuff we send into space, all of the original metal atoms are still on the earth, but they're all either (i.e. under the ocean or whatever) or not economically concentrated.

[Topgun]

so how long before the lost metals turn to ore again?

[Mars]

I don't know if they ever do.

IDK if it's possible to smelt rust, for example.

Or copper sulfate, or aluminum oxide, ect...

[castor]

Hmm... I wonder, how would one "deliver the goods" from a mined asteroid?
Can't think of anything else feasible but orbital bombardment myself

[Black Wolf]

so how long before the lost metals turn to ore again?

Millions, potentially billions of yearts. In most cases they have to be tectonically recycled and then redeposited, though a few special cases might re concentrate on a shorter scale (still in the tens to hundreds of thousands of years though)