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 Maniac_nmt wrote:

That is the trick though, it requires the planet to have undergone specific formative processes to get those rare materials. The 'just mine for it' does not necessarily hold water.
...

No it doesn't. Rare earth metals are not that rare at all. Most of them are quite common, and are likely available from asteroid mining. They are only called rare due to the fact that they are difficult to find in any great quantity on earth. Due to various processes they do not form deposits in the same way as, say, iron or gold.

 Maniac_nmt wrote:

It requires the materials to be present in the area and created during the formation of the star system of some sort. Ergo, the formation of the planet. Higher order elements tend to be less stable, not all of them, but many. This is also chemistry 101. Chemical and situational reactions create certain isotopes, as an example.

No it dosn't. Most of the elements on earth come from stars. Most isotopes are naturally occurring, created by the decay of other elements. Some are created naturally through things like cosmic ray collision, for example carbon 14:

1n + 14N → 14C + 1p

Others we create through collisions in partial accelerators.

Non of these things require any circumstances that are unique, or even unusual, to earth. (Apart from, arguably, the existence of a life form advanced enough to create a particle accelerator, but that is a different matter)

 Maniac_nmt wrote:

Secondly, yes, formation of the planet does cause certain characteristics. Sans a large ocean, as an example, with healthy marine life you do not form coal, bitumen, petroleum, or similar products. Such products are vital for any long chain polymer based materials. So rayon, gortex, polyester, nylon, some metals, all sorts of super plastics, etc do not exist without 'oil' and it is only certain parts of oil that actually contain this material. Such materials are very difficult to synthesize (if not impossible) and are not available through stellar formative processes.

No they are not. Petrochemicals are easy to synthesis.

Sabatier reaction
CO2 + 4 H2 → CH4 + 2 H2O

Gives you CH4, Methane. In fact it is useful in space as you use up a waste product (CO2) and make water to drink, or crack it to make breathable oxygen and more hydrogen for further reaction.

From there you can create C2H6, and so on. All you need is CO2 (Which is a waste product you would have lots of) Hydrogen, which is fething everywhere in space (Just scoop it up as you go) and energy, which if you can build a fusion reactor in space is not a problem at all.

Creating hydrocarbons is not impossible, or even difficult. The reason we don't do it on a mass scale at the moment is that it dose use allot of energy which, for us on earth at the moment, mostly means burning other hydrocarbons, making it both self defeating and prohibitively expensive.

Materials for building a space craft in space are not a problem at all. If you can overcome the issues of processing and fabrication in space then getting hold of the raw materials is trivial.

It should also be pointed out that the Imperial battle-fleets use real-world naval tactics as their basis, rather than the dog-fighting tactics we see in things like Star Wars, where even capital ships can turn on a relative dime.

The ships of the Imperial Navy are huge, ponderous and slow and, yes, it might take then 150,000 kilometers of space to come about 5 degrees from their course. This is why they arrange their battle-lines the way that they do, with the smaller, more agile ships acting as escorts for the "big guns" on the battle-cruisers and other fleet capitals.

I've always wondered how planets aren't completely obliterated whenever there is a battle with spaceships of this size in relative proximity. If an asteroid with a diameter of 1km would obliterate earth, what happens when a ship is blown to pieces and they come raining down on a nearby planet? This has always been a question in science fiction to me. Happened like mad in Mass Effect. Star Wars, the same thing...how was the forest moon of Endor not covered in giant burning materials after the Death Star was blown up?

Is there a scientific reason for this not happening or is it just overlooked?

Mass is not really an issue in space...
So space could be as large as you want them to be.
Resources to build them are also not an issue with the massive size of the Imperium.
And it is not that such an spaceship would ever need to land on a planet. Most spaceship crew in 40k spend their entire live on their ship. They are born on their ship, they marry another crewmember, get kids and die on their ship. Spaceships in 40k are like entire worlds floating in space.

The larger the ship, the harder it is to preform complicated maneuvers and the less feasible it becomes to leave the void of space. That's pretty much it.

 Reckoner wrote:
I've always wondered how planets aren't completely obliterated whenever there is a battle with spaceships of this size in relative proximity. If an asteroid with a diameter of 1km would obliterate earth, what happens when a ship is blown to pieces and they come raining down on a nearby planet? This has always been a question in science fiction to me. Happened like mad in Mass Effect. Star Wars, the same thing...how was the forest moon of Endor not covered in giant burning materials after the Death Star was blown up?

Is there a scientific reason for this not happening or is it just overlooked?

depends on how fast it is going. If it was just in orbit and fel, it wouldnt be going as fast on impact as it would if it had solar escape velocity and fell.


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 Iron_Captain wrote:
Mass is not really an issue in space...
So space could be as large as you want them to be.
Resources to build them are also not an issue with the massive size of the Imperium.
And it is not that such an spaceship would ever need to land on a planet. Most spaceship crew in 40k spend their entire live on their ship. They are born on their ship, they marry another crewmember, get kids and die on their ship. Spaceships in 40k are like entire worlds floating in space.

mass is an issue to make it go fast. The heavier it is the more power you need. but unless they are so massive that they start to generate a ton of gravity it is not a problem for them to exist.

 Reckoner wrote:
I've always wondered how planets aren't completely obliterated whenever there is a battle with spaceships of this size in relative proximity. If an asteroid with a diameter of 1km would obliterate earth, what happens when a ship is blown to pieces and they come raining down on a nearby planet? This has always been a question in science fiction to me. Happened like mad in Mass Effect. Star Wars, the same thing...how was the forest moon of Endor not covered in giant burning materials after the Death Star was blown up?

Is there a scientific reason for this not happening or is it just overlooked?

It was.

http://www.theforce.net/swtc/holocaust.html
http://starwars.wikia.com/wiki/Endor_Holocaust
http://www.youtube.com/watch?v=lyftNww4kqA&noredirect=1

.... and there are many planets in the Imperium that are damaged by capital ships falling into their atmospheres. Remember, though, that most of these ships are not moving particularly quickly (relative to the speed of the planet), and are not fighting in the upper atmosphere, so what you end up getting is a ring of a debris cloud around the planet in a decaying orbit, which slowly over centuries or millennia, falls back through the atmosphere of the planet and burns up.

Rare planets have, like, a massive battle-ship plowed nose-first into the ground like a fething dart.

 Steve steveson wrote:

 Maniac_nmt wrote:

That is the trick though, it requires the planet to have undergone specific formative processes to get those rare materials. The 'just mine for it' does not necessarily hold water.
...

No it doesn't. Rare earth metals are not that rare at all. Most of them are quite common, and are likely available from asteroid mining. They are only called rare due to the fact that they are difficult to find in any great quantity on earth. Due to various processes they do not form deposits in the same way as, say, iron or gold.

 Maniac_nmt wrote:

It requires the materials to be present in the area and created during the formation of the star system of some sort. Ergo, the formation of the planet. Higher order elements tend to be less stable, not all of them, but many. This is also chemistry 101. Chemical and situational reactions create certain isotopes, as an example.

No it dosn't. Most of the elements on earth come from stars. Most isotopes are naturally occurring, created by the decay of other elements. Some are created naturally through things like cosmic ray collision, for example carbon 14:

1n + 14N → 14C + 1p

Others we create through collisions in partial accelerators.

Non of these things require any circumstances that are unique, or even unusual, to earth. (Apart from, arguably, the existence of a life form advanced enough to create a particle accelerator, but that is a different matter)

 Maniac_nmt wrote:

Secondly, yes, formation of the planet does cause certain characteristics. Sans a large ocean, as an example, with healthy marine life you do not form coal, bitumen, petroleum, or similar products. Such products are vital for any long chain polymer based materials. So rayon, gortex, polyester, nylon, some metals, all sorts of super plastics, etc do not exist without 'oil' and it is only certain parts of oil that actually contain this material. Such materials are very difficult to synthesize (if not impossible) and are not available through stellar formative processes.

No they are not. Petrochemicals are easy to synthesis.

Sabatier reaction
CO2 + 4 H2 → CH4 + 2 H2O

Gives you CH4, Methane. In fact it is useful in space as you use up a waste product (CO2) and make water to drink, or crack it to make breathable oxygen and more hydrogen for further reaction.

From there you can create C2H6, and so on. All you need is CO2 (Which is a waste product you would have lots of) Hydrogen, which is fething everywhere in space (Just scoop it up as you go) and energy, which if you can build a fusion reactor in space is not a problem at all.

Creating hydrocarbons is not impossible, or even difficult. The reason we don't do it on a mass scale at the moment is that it dose use allot of energy which, for us on earth at the moment, mostly means burning other hydrocarbons, making it both self defeating and prohibitively expensive.

Materials for building a space craft in space are not a problem at all. If you can overcome the issues of processing and fabrication in space then getting hold of the raw materials is trivial.

Right, rare earths are incredibly common, but finding them in useful concentrations can be difficult and refining them is expensive.

And our sun does not create very much in the way of heavy elements. All that is on earth was from other stars and is just as likely to be found in asteroids. In fact more likely. All the heavy stuff has sunk into the core of the planet. But on an asteriod there is only micro gravity and you can find plenty of heavy stuff like gold.

yeah Maniac, I don't get what you are driving at. First off, if we are talking about Chem 101 radioactive metals don't begin to decay until they freeze... so any planet with a liquid outer or inner core (where radioisotopes will be concentrated) will have basically the same daugher/parent ratio as it did at accreation. The only reason our radioisotpes are decayed is because they are products of the late heavy bombardment.... and therefore not in their 'right' place.

I don't see how you think you can get around mining. Everything that you have ever eaten, used, bought, whatever in your life that was a tangible thing was either extracted from the ground or harvested from a living thing. Those are the only two possible options. For anything that isn't harvested you HAVE to mine/extract. Even if in the future fusion is convenient, the scale is going to be far far far to small to match the efficency of mining. So... no, you're wrong. Mining holds plenty of water.

EDIT-- also, resource richness has very little to do with the ability to support life. Even in the case of volatile hydrocarbons. I mean, Titan would be practically Planet Exxon if we could extract it cheaply, but it probably couldn't support anything outside of the most hardcore extremophile germs. And DRAIIIIIIIIIIIIIIIIGOOOOOOOOO

 Reckoner wrote:
I've always wondered how planets aren't completely obliterated whenever there is a battle with spaceships of this size in relative proximity. If an asteroid with a diameter of 1km would obliterate earth, what happens when a ship is blown to pieces and they come raining down on a nearby planet? This has always been a question in science fiction to me. Happened like mad in Mass Effect. Star Wars, the same thing...how was the forest moon of Endor not covered in giant burning materials after the Death Star was blown up?

Is there a scientific reason for this not happening or is it just overlooked?

That asteroid is incredibly fast and dense. Ships falling into a planet are not. That's why a satellite falling to earth really is no big deal, but even meteors the size of a pea are so dangerous. Velocity matters much more than mass.

 Reckoner wrote:
I've always wondered how planets aren't completely obliterated whenever there is a battle with spaceships of this size in relative proximity. If an asteroid with a diameter of 1km would obliterate earth, what happens when a ship is blown to pieces and they come raining down on a nearby planet? This has always been a question in science fiction to me. Happened like mad in Mass Effect. Star Wars, the same thing...how was the forest moon of Endor not covered in giant burning materials after the Death Star was blown up?

Is there a scientific reason for this not happening or is it just overlooked?

Well, keep in mind when we say a 1km asteroid would obliterate Earth we mean it would destroy a large chunk of the ecosystem. Which in turn would mean mass death from lack of food. No way is anything as small as a 40k ship going to cause damage to the actual planet(planets are HUGE!)


But in the case of a hive planet with no real reliance on the natural ecosystem there would be little damage beyond whatever happened as a direct result of the impact. Plus the planet might have climate control mechanisms which could easily compensate for excess dust in the atmosphere.

And when a ship is destroyed in battle it rarely stays intact. It would most likely fracture into many smaller pieces which can't hurt the planet itself.

And these battles aren't happening super close to the planet all the time. They'll happen many hundreds of thousands of kilometers away much of the time.

Much of the debris will likely end up in a stable orbit and end up raining down in much smaller chunks.

 Silverthorne wrote:
radioactive metals don't begin to decay until they freeze.

Radioactive material stays radioactive no matter what state it is in. Molten metals stay radioactive, otherwise nuclear reactor meltdowns would be self limiting, stopping the reaction as the fissile material stops reacting.

 Silverthorne wrote:

I don't see how you think you can get around mining. Everything that you have ever eaten, used, bought, whatever in your life that was a tangible thing was either extracted from the ground or harvested from a living thing. Those are the only two possible options. For anything that isn't harvested you HAVE to mine/extract. Even if in the future fusion is convenient, the scale is going to be far far far to small to match the efficency of mining. So... no, you're wrong. Mining holds plenty of water.

I THINK you are replying to my comment, not Mainac with that one... If not I suggest the use of quotes.

Not sure what you mean by that. If you take a very broad meaning for harvesting, then yes, until we come up with a way of creating elements from the primordial soup of the fabric of the universe, we have to harvest everything. However, we get many many things from sources other than mining or "harvested from a living thing". We extract gases from the air, we extract minerals from sea water. We make radioactive elements isotopes in partial accelerators all of the time for nuclear medicine.The creation of hydrocarbons from CO2 and H2 is not just a theoretical concept but a very real prospect in the near future. Once we can get reliable clean energy it is likely to be a major source of both long chain hydrocarbons and for CO2 sequestering. Hydrogen and electric will hopefully be used for fuel, but for things like plastics then it will likely be much cheaper than extracting things like shale gas and off shore oil.

 Maniac_nmt wrote:
The 'just mine for it' does not necessarily hold water

No, I wasn't answering you, steve.

The only point you listed that is not either an extraction or a harvest is the case of nuclear medicine. Which is negligible. So the only rival to giga-scale mining (which we do currently) is a few hundred pounds of drugs given to cancer patients around the world? Between that and every nuclear warhead (assuming plutonium... I'm not privy to what the Iranian program or other active enrichers are aiming for) you are looking at what, a ton? Two tons? Of material. NASA is one of the largest plutonium enrichers in the United States and they produce.... wait for it.... 1.1-1.5 kilos a YEAR. You know how long it will take to make a space ship out of 1.5 kilos a year?

With all of your points, including the very intriguing catalytic isolation and concentraion of Carbonic Acid from sea water (a hugely energy negative reaction, by the way... good thing we have a N at the end of CV these days). It is still an extraction or a harvest. Doesn't matter if you are extracting out of sea-water (very rare) the atmosphere (very rare) or sedimentary beds (common) it's an extraction. The only one that is not an extraction is fissile products which no reasonable person can believe will be able to produce enough raw materials for any sort of large scale industry requiring their products as a base material.

It's not a reasonable or defensible argument to assume that fission/fusion products we make in limited small reactors, now or in the future, will be as convenient a source of material as harvesting the products of stars and supernovas, which produce material on a scale that boggles the imagination. Its like how cheap labor suppresses labor saving inventions.... if we can pick the unobtanium up off the moon/asteroid/planet surface, why build some huge expensive dangerous contraption to produce a fraction of the same amount every year?

As for decay-- I'm a geologist not a nuclear engineer. My understanding of radioactivity comes from rocks and radioactive dating-- where the decay only begins after the rock has cooled and crystallized. If rocks could decay while molten or even just plastic they would not be useful for radiocarbon dating but yet they are... My understanding from my Navy days of what goes on in the reactor (magic rocks make hot water) is that you have plenty of alpha particles bouncing around once a reactor scrams or goes supercritical and if the unstable U-238 nucleus is bombarded by one particle the reaction will continue-- however in regular unenriched uranium the bombardment is not heavy enough to trigger a fission event so it just sits there.... Again there are doubtless people more knowledgeable than me about that but that is my understanding.

I see what your saying. On the mining point I think we are talking at cross purposes to some extent. I agree with you on the practicality. I thought you were talking about my remarks on hydrocarbon syntisizing. And as with anything practicality and possibility are two different things. Mining will continue as long as it is the more practical method. Be it nuclear material, hydrocarbons or whatever else.

On the point of nuclear decay, state makes no difference. Molten salt reactors use molten uranium.

Radioactive dating can be done because the uranium trapped in zircon crystals. Zircon, however, strongly rejects lead whilst molten. So therefor any lead in the zircon must have come from the decay of uranium in to lead after the rock formed.

I really want to see the magic JP5 maker reach IOC. It's just such a game-changer, not being tied to the Oiler. The small-boys will still need it around but UNREPS with DDGs and CGs is not the hours-long, Please Bomb Me exercise that it is with the CVs. Hopefully the new SMRs will replace the LM2500s in the near future and then only the air wing will need hydrocarbons. But instead of cool, tactically relevant systems we are dumping treasury notes on corporate welfare like the LCS and F-35. Gross.

I understand DARPA were/are working on a truck sized fusion reactor for just that reason. Making JP5 and running all sorts of cool electric and hydrogen fuel cell stuff. However, as with anything DARPA do it probably only has about a 50% grounding in reality.

Realistically in real life? Short answer? No. Long answer? Noooooooooooooo.

Of course much like Star Wars, Star Trek, Halo, and other numerous Sci Fi universes, W40K throws logic out the window. While it's feasible for them to have such massive ships, they probably wouldn't work in real life. But they're 'reasonable' in W40K.

Although with some Sci Fi like Star Wars and Star Trek, you have to remember they also have access to far more advanced assembling tech- even than W40K. Star Wars has molecular forges that allow them to assemble rare metals and materials for production of starships with more ease than scouting for extremely rare metals- although it still is resource intensive. IIRC, Star Trek uses their replicators on a macro scale for ship production as well.

Star Trek also mines entire nebulae for their materials, which are then fed into replicators to construct, well, anything.

 Psienesis wrote:
Star Trek also mines entire nebulae for their materials, which are then fed into replicators to construct, well, anything.

That as well. Stars and their associates are extremely useful for production of heavy metals, as nebulae are rich in hydrogen and other basic compounds and can be compacted into a miniature star to pump out heavy metals. W40K also does this as well IIRC, with plasma being a main source of power for their ships that can generate even more energy than a small star. Also, unlike Star Wars, W40K realizes than when your ship is powered by a small star in its core, it's gonna detonate with a big explosion. For example, Impstardeuces in Star Wars generate more energy than Sol yet don't really make much of a bang when detonated or their reactor goes critical and detonates. One large W40K power ship kitted out fully with plasma reactors filling up the ship entirely- detonated with such force it unleashed miniature supernova.

 Grey Templar wrote:


Well, keep in mind when we say a 1km asteroid would obliterate Earth we mean it would destroy a large chunk of the ecosystem. Which in turn would mean mass death from lack of food. No way is anything as small as a 40k ship going to cause damage to the actual planet(planets are HUGE!)


But in the case of a hive planet with no real reliance on the natural ecosystem there would be little damage beyond whatever happened as a direct result of the impact. Plus the planet might have climate control mechanisms which could easily compensate for excess dust in the atmosphere.

Actually, read "Betrayer" - fall of first Lorgar's flagship was not a piece of cake even in purely physical damage. But this was Gloriana-class - primarch-worthy colossus dwarfed only by Furious Abyss class.


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 Wyzilla wrote:

 Psienesis wrote:
Star Trek also mines entire nebulae for their materials, which are then fed into replicators to construct, well, anything.

That as well. Stars and their associates are extremely useful for production of heavy metals, as nebulae are rich in hydrogen and other basic compounds and can be compacted into a miniature star to pump out heavy metals. W40K also does this as well IIRC, with plasma being a main source of power for their ships that can generate even more energy than a small star. Also, unlike Star Wars, W40K realizes than when your ship is powered by a small star in its core, it's gonna detonate with a big explosion. For example, Impstardeuces in Star Wars generate more energy than Sol yet don't really make much of a bang when detonated or their reactor goes critical and detonates. One large W40K power ship kitted out fully with plasma reactors filling up the ship entirely- detonated with such force it unleashed miniature supernova.

Not necessary - unlike fission pile, fusion reactor essentially "burns" fuel - i.e. in any given moment there's very limited quantity of ignited fuel, while rest of it is inert matter. So if next portion of that fuel is cut off then all you deal with is residual heat from previous portion. While in SW it's still sh!tload of energy and authors don't understand that, in WH40K (and Battletech universe) you can realistically had containment breach or reactor damage WITHOUT catastrofic explosion - btw in BL books ship explosions are rarer than one can think, and often they are result of other system's failure - there's warpdrive, realspace drive, exotic weapons and self-destruct modes to choose from.

When you have the technology available to create artificial gravity, then yes its feasible.

one thing to consider regarding rare elements is that it might be possiable in the 40k universe to "make" them.
often these days when a new element is discovered it's because we bombard atoms of other elements with electronics until their atoms begin to pick them up. it's HUGELY expensive and the half life of all of these new elements is tiny, however it's certinly possiable that the admech has some old technology hidden away somewhere, perhaps from a STC, that allows them to turn one element into another.

the age old alchemical trick of turning lead into gold could, with the right tech, be possiable

It's possible now. Just irradiate the lead. Bang, you got gold.

Radioactive gold, to be sure, but still gold.

BrianDavion wrote:
one thing to consider regarding rare elements is that it might be possiable in the 40k universe to "make" them.
often these days when a new element is discovered it's because we bombard atoms of other elements with electronics until their atoms begin to pick them up. it's HUGELY expensive and the half life of all of these new elements is tiny, however it's certinly possiable that the admech has some old technology hidden away somewhere, perhaps from a STC, that allows them to turn one element into another.

the age old alchemical trick of turning lead into gold could, with the right tech, be possiable

The trouble is that we know the elements. The only way to create "new" elements would be to create elements even heavier (and therefore even less stable) than the heaviest elements theorised today; these elements, while new and possibly viable for other sciences, are not going to be "Indestructanium". That's why sci-fi often delves into fictional materials with hinted components; ceramite, for example, is most likely an extremely hard ceramic compound. As ceramic compounds are known to be viable for armour plating (and to vary in strength based on their constitution), it is entirely possible that extremely advanced technology will be capable of producing ceramic armour that is practically indestructible by modern-day standards. Other things like carbon nanotubes are common, but mostly this is why "energy shields" are so popular. Energy shields can be of any strength (depending entirely on technology level, in most sci-fi), so their ability to withstand damage is never called into question. It would be different if power armour was described as being made of steel, as steel is a material we know the properties of. Because things like "plasteel", "ceramite", "rockrete", "adamantium", "wraithbone" and so on, we accept that this fictional material's properties make it capable of doing the things it does in the fiction.

Back to the original point, though; there will never be an "adamantium" element, just an extremely strong/tough/hard material of some sort.

It is theorized that there is a stable band of heavier non-radioactive elements. So it is possible for there to be an undiscovered super heavy element that doesn't give you cancer just by looking at it.

The major issue with manouvering large space vessels would be g force stresses on the superstructure when turning in any direction. Also without front facing engines as well as rear facing, the only option to decelerate is to spin the entire vessel 180 degrees and fire off the engines again. If you want to read some relatively realistic space manouvering and fighting, try "The Risen Empire".

40k ships do have retro-thrusters for maneuvering. Its just the most powerful, and most obvious, engines are rear facing.