I'm watching a nice little documentary right now about the moon landings, as part of a BBC4 series of programmes about the 40th anniversary of the moon landings. It's really good, and its got me thinking about how Rogue Traders actually go about doing what they do.

So here's some random questions to throw out there and see what people think:-

1. What's the ratio of un-useable worlds to habitable worlds at large in the galaxy? If there are 50-75 odd inhabited worlds in a sector, how many UNINHABITED rocks are there? 1:1 habitable to uninhabitable? 1:75 habitable to uninhabitable? 1:75,000? Presumably there are lots of uninhabited systems...or are there? Does every system have a lonely Imperial outpost space station in?

2. How does a Rogue Trader decide where to start looking for, say, habitable worlds in this inky blackness?

3. How do Navigators actually Navigate? Yes, I know they have a warp eye, and can see the warp... but what are the mechanics of this process? Do they dive into the warp, open their eye and steer accordingly? Or can they see the warp without being in it? Wouldn't that drive you mad? If they steer using the astronomicon, how does this appear to them? Like the beam of light from a lighthouse? Wouldn't the beam need to be a particular shape and beamed across the whole galaxy to allow 3 dimensional navigation? Or is it even more complicated than that?

4. How do Navigators tell other navigators where to go when they find a world? Or to put it another way, how do they map their journeys? I love the maps in the DH book, but the fact they are all quite different suggests that either they are not designed for Navigators, or that the process of Navigation is somehow highly subjective. How does this work?

5. What are Imperial ships fuelled by? Yes, I know, warp engines and plasma drives. But what do these things run on? Warp matter? Promethium? Coal? Are they like super nuclear submarines that only need to be refuelled every few centuries? Or do they need to be refuelled every journey? Or are they only limited by the amount of food they can carry?

Any thoughts?

1. Has the same answer as "How many angels can dance on the head of a pin?" -- As many as wanted or as needed. It's a big galaxy, and it's not hard sci-fi so there's not going to be any given ratio.

2. Second star to the right, and straight on till morning.

3. Hmm.. this I don't know. Considering some of the "ahem" pictures I've seen on the internet depicting how technology is repaired by tech priests, I don't think I really want to know.

4. Not a clue.

5. Do you really think that the reason the ships are so big and have massive crews into the thousands is because people get lonely in 40k universe? No. You need some extra fuel, throw an acolyte on the fire. The same can also be done for field rations.

In all seriousness though, I would expect many of these questions will be answered when the book actually comes out.

1: Short answer - as many as you need. The galaxy is a very big place and warp-capable ships can travel a long way. Also remember this is not Star Trek where every useful world needs to be an earth-like class M planet. Hell, just looking through most 40k background you'd think they deliberatly choose the really harsh places to settle.

2: Think 17th century sea travel - i.e. rumours, rough maps and bold undertakings to plunder far off lands - 'there be gold in that thar star system'.

3: I imagine the whole process is like the Navigator is the guy sitting on the bough of the ship looking for lights and land on the horizon while keeping an eye on the sky and sea for dangerous currents and bad weather. Then when he sees something he shouts out to the captain and helmsman and they react accordingly.

4:I think finding a new world is more about charting a safe passage to it through the warp rather than getting exact astrological co-ordinants. And since the warp is so changable this could be quite a round about route to avoid storms, rips and tides - it could also take into account time-dilation (I believe most 40k charts are in 4 dimensions). After all there is no use knowing how many hundred light years away a star is if you don't know how to get there through the warp.

5: I'm guessing anything the size of an Imperial starship would have its own self sustaining reactor - whatever that is and whatever it runs on. Being 40k, and with thousands of years of history, I would guess each ship is slightly different. Of course that is not to say that like all ships they would not need resources to keep them running - such as fuel for auxillary systems, food and ammunintion, constant internal and external structural repairs. I also imagine alot of ships would have a pretty high crew turn over...

1. Scientifically speaking, and using the Sol system as an example, 10% of planets orbiting a yellow star. Beyond that, we do not have enough information to guess.

2. As stated above, yellow stars would be the first place they would look. After that, they would check the red dwarfs. According to our sciences, the yellow stars, and red dwarfs would be the only ones stable enough to develop habitual planets. Within a star system, the Trader would head straight for the "Golddy Locks" zone, where in would not be too hot, or too cold for liquid water, the main element of life, (as we know it.) But why would the Trader limit himself to habitable worlds? There are mainly worlds that are not habitable, but are rich in minerals. One example of this is; the Squats, (before they went extinct,) had huge zeppelins that would mine useable gasses from the atmospheres of Jovian class planets.

3. There was a book called "The Eye Of Chaos," (haven't read it? count your blessings,) That described the navigator’s perception of the warp as some form of terrain. Some saw the warp as a city, some as a jungle, each saw it differently. The closer they got to the Eye Of Chaos, the more confused the terrain would be. Outside the EYE, the vessel would travel where the Navigator willed it to go, inside the Eye, it was where the navigator desired it to go. The astronomicon appears as a light in the distance. Considering the quality of the book, all this might be rewritten.

4. I have never read anything on this subject.

5. In the original form of Battle fleet Gothic, there was a type of tanker that was several orders of magnitude bigger than the largest warship. I could produce fuel by flying near a star, wile being supported by every power plant on the adjacent planet. This leads me to believe that the fuel is some form of antimatter. Helium three could also be a possibility, but it would be easier just to mine it off the surface of airless moons.

Lightbringer said:

1. Depends on your definition of "habitable" and whatever you feel is appropriate. It also depends on the type of star and the relative distance from the star to the planet.

2. Afix a local starmap over a dart board and start playing with those throwing knives he has sewn into his gloves. What? It's as good of a method as any.

3. No idea.

4. No idea.

5. Most likely the same things our sun is fueled by, a combination of hydrogen and helium brought together in nuclear fusion...

1) Depends. I suspect that every system acknowledged to be part of the Imperium will have at least one 'habitable' planetoid, even if that merely means a research/mining outpost on a dead moon, but that there will be a number of star systems, even within a sector which hold nothing of value (when the cost of exploiting the system and hauling away the loot is taken into account), and as such are not acknowledged. I don't know about you, but I'd put 'worlds inhabitable by terrestrial life' pretty **** high on the list of valuable resources.

2) Ancient data from before the Age of Strife? The Imperial Tarot? Spectrographic analysis of the star from 'nearby' imperial worlds? Those are probably the best methods, shortly followed by hunches, then rumours. The astrographic map over a dartboard has a few problems- not least of which is the fact that even an incredibly fine dart, when thrown at a map of a useful scale, will leave a hole covering several dozen square light-years, quite aside from the fact that such a map is only going to be in two dimensions...

3) Apparently, if the third eye is open and uncovered, they can see the warp. Doesn't matter if they're in real space or the immaterium. Yes, that carries a risk of insanity, which is one reason they tend to wear the bandanna/blindfold bits. The exact manner in which they perceive the warp is apparently highly subjective, which raises questions I'll come to later. While in the warp (and, y'know, actually navigating ) they take position in the Eyrie, remove the blindfold/bandanna, look around and either steer accordingly or pass instructions to steer accordingly. The Astronomican and similar psychic beacons may be used as useful 'fixed' points of reference, appearing as something bright and/or pure and good, depending upon the oeuvre appropriate to their own perception of the warp. The metaphor of a lighthouse is probably a good one, although probably imperfect and flawed- we are effectively blind men trying to describe yellow.

4) As I noted, given that every Navigator perceives the warp in a different manner, making charts and logs that are usable by more than a small fraction of Navigators (if not solely by their creator) would pose something of a problem. I suspect the various Houses have got around that by making trips with more than one navigator and agreeing on a shared terminology to describe the storms, flows and currents they 'see'. Since the early training jumps of a navigator are undertaken with a senior navigator as an instructor, the knowledge and terminology can be passed along (at the very least for the phenomena close to whichever system the training is nominally occurring). While I suspect that each House will have its' own codes, charts, logs and rutters (their own Navis Prima, effectively), there must also be a common code used by all Navigators, as there have been mentions of charts in the hands of the Imperial Navy (that could be read by the officers, not merely the Navigators), and there is no guarantee that a ship will have Navigators assigned to it from only one House for its' entire working life (to say nothing of the need to transmit courses between ships when proceeding in squadron),
The maps in the DH core book are, in my opinion, nothing more than fanciful pieces of artwork that have been produced from actual maps and charts in order to make certain Imperial officials and/or nobles seem far more cosmopolitan than they actually are, although it is possible that their differences can be explained by the maps' origin- different Houses, different mapping conventions.

5) Plasma drives, apparently, require regular refuelling- partly, I suspect, because they are not massively efficient and horribly fuel-intensive, and partly because they are always active, powering the ship in general. As to the nature of that fuel, my guess (and I regret, it must be only a guess, albeit one based on a wide reading of 'hard' sci-fi) is a slurry of deuterium, and/or possibly He-3 (the latter, I suspect, is more efficacious, the former easier to get). Logically, the ship must be able to carry sufficient to make at least one voyage, one way (which, given the nature of warp travel can probably be assumed to mean an absolute minimum of one month's tankage, with a six months to a year being preferable as minimums), plus sufficient life-support for the same (food, water and air, for the entire crew- a not inconsiderable amount of mass, altogether). I can see the urge to top up on reaction mass and life-support being a reflex action whenever a ship makes planetfall (or docks at a station or whatever).
Warp drives, on the other hand, require replenishment far more rarely, which is lucky, since the process of refuelling is said to be the most hazardous a ship can undergo, combat included. The fuel is, presumably, highly radioactive, as it is only handled by servitors wearing heavy lead suits (and are still burnt away by the energies coming from the fuel canister). However, since said fuel canisters are covered in thick layers of hoar frost, it seems likely that there is something even more esoteric than just plain radiation- some kind of psychic fuel as well, perhaps?

Sources: Eye of Terror , Execution Hour , Legacy , Star of Damocles and a short story whose name escapes me. Also- this

As far as "fuel" goes, as someone has mentioned, "Space Fleet" described one process of obtaining fuel. Basically a large factory vessel sucked stellar matter from the surface of a star using powerfields, which it then used to power the process of converting harvested ore into "super energised plasma fuel", which was then described as " a thousand times more energetic than nuclear fuel ".

In other words, the stuff that fuels Imperial starships has an extremely high energy density compared to nuclear fuels, without doing some maths, which my pizza deadened mind is incapable of at the moment, its ludicrously powerful stuff, and its moving from fusion and fission into annihilation energies.

Its also likely superdense, which it'd need to be for Imperial starships to get away with their massive reaction engines, which means they might use it for reaction mass (the stuff they shoot out of the ships backside to make it move forward) as well as fuelling their power plants.

Lightbringer said:

It's probably impossible to explain. Sort of like trying to tell a blind person who has been blind since birth what the colour blue looks like.

Real world astronomy gives an answer to the question of how many inhabited systems there are compared to empy ones that fits fairly well with the established game canon.

There are an estimated 200 billion stars in the Milky Way galaxy (some estimates actually double that). The Imperium of Man, the most widespread and populous empire in the galaxy, rules a million inhabite star systems. If we assume that the Imperium accounts for half of the inhabited worlds of the galaxy, with the rest being cut off by warp storms, beyond the reach of the Astronomicon on the Eastern Fringe or just undiscovered in some fogotten pocket of the galaxy, then there are 100,000 lifeless worlds for every inhabited system.

This isn't actually an unrealistic ratio, given some projections of how common life-bearing worlds are likely to be.

On the face of it, this means that it's going to be an impossible task to find new systems with anything of value in them. Another astronomical fact comes to the rescue here- stars tend to be group in clusters of similar age. Therefore, if you find one star with the right conditions for a planet habitable to humans present in the system, it's very likely there will be several others nearby.

This fits the Sector model of the Imperium, where clusters of maybe a hundred worlds are found close together and vast gulfs of empty space lie between them. It also fits the descriptions we've had from several sources of whole sectors of dead worlds orbiting stars at the end of their cycles, covered by the ruins of eons-dead Xenos civilisations.

This is how the Imperium is able to dominate the galaxy, while at the same time being surrounded by the unknown and occasionally stumbling over lost worlds and pocket empires. It's hard to find the inhabited systems, but when it does, the Imperium will always have some sector near enough to act as a staging area for invasion.

A navigator's warp eye SEES the warp. It's almost like having a daemonic eye. However their brain renders it in an image they can understand, unique to each navigator. The one in the Farseer novel iirc saw it as a never ending green forest.

The beacon of the astronomicon is simply there as a lighthouse, an immobile point in space that navigators can take their bearings from. Like the stars or the sun to primitive mariners. A navigator says 'if the beacon is there and I am here, Gundi Prime should be THAT way.'

Of course, that raises the question, what were the navigators using BEFORE the beacon was created during the great crusade?

Hellebore

Hellebore said:

Knowledge of how the Immaterium was flowing in their local mixed in with educated guess-work?

Hellebore said:

I've read background - from quite some time ago (and of somewhat uncertain legitimacy - it's an old Citadel Journal article, written by a GW writer, other elements of which, such as the pseudopsychic powers wielded by Navigators, have since been adopted and reused as canon in other sources) - that suggests that the Emperor created the Navigators in one of his previous guises. This would go a long way to explaining their loyalty to him, and might well solve this apparent issue.

For all intents and purposes (with regards to Imperial warp travel), the Astronomicon is only visible to the Navigators - nobody else can look into the Warp in that way to see it, so all the non-Navigators only know it exists because the Navigators and the Imperium tell them it does. The beacon is directed by the Emperor himself, at least in theory, as nobody else could do it, but while it may have been powered by other psykers since at least part-way through the Crusades, that does not appear to have always been the case; afterall, the Emperor travelled with the early Crusade Fleets for quite some time, before his return to Terra, during which time he couldn't have directed the Astronomicon as he does in the post-Heresy Imperium.

It may well be that, before the static beacon was set up, the Emperor actively aided the Navigators rather than providing a passive landmark for them - a state of affairs that could have been going on in secret for thousands of years before the Reunification of Terra...

Interesting stuff, No-1. Navigators are a fascinating feature of 40k, and I've always been intrigued with them since the original RT back in '88. The first character I rolled up was a Navigator, using the old random weapons tables.

The other interesting thing about the Navigators is the Paternovae, the "changed" patriarch of the entire subspecies, who rules from a palace on Terra. There was some great background on him, the heirs apparant of each Navis Nobilite great house and their battles for succession in an old WD, I think number 132, the Spacefleet issue. It was actually one of those rare gems, a White Dwarf that contains new ideas and new background

Navigators are definately very very weird, a psychically and genetically engineered race ostensibly created by humans but run totally by themselves...

The emperor's involvement in their creation makes sense. The two key technologies that the Imperium is founded upon are:-

1. Psychic/warp engineering (the astronomicon, warp engine,)

2. Genetic engineering (the space marines)

Navigators are a combination of both of these technologies.

The Emperor was the source of both sets of technology. Human psychic engineering is pretty weak compared to the stuff the Eldar get up to, but the Emperor himself seemed to have a phenomenal grasp of the subject, far in excess of what any other human was capable of. If anyone is going to tinker with human genetic code in such a way that it enables warp navigation, it's him.

Navigators navigate by relaying what they see while at Warp to the Bridge in the form of course changes. Thier own interpretations on the patterns of the Warp differ massively. Star charts help a Navigator keep an eye on where the ship is in Realspace terms, using the light of the Astronomicon as an indicator in which direction Terra lies. How this is mapped has never been covered, but I would imagine that this involves noting down a point in Realspace in relation to Terra first and foremost

Plasma reactors run on hydrogen. The hydrogen is broken down by the reactor to produce the masses of energy needed, apparently creating the processes that normally happen inside a star within the magnetic confines of the reactor

On the subject of fuel and power, I imagine imperial ships would operate according to the same praxis which is said to govern other Imperial engineering. Namely, inefficiency, lethality, enormous power, and adaptability. The Engine of a Leman Russ, for example, is said to be able to run on nearly any combustible material. While not terribly sophisticated in theory, it is still a bit of tech far more useful (especially in a war zone and amongst the vagaries of space travel) than a more specialized and advanced piece of engineering might be. The perfectly 'Universal Engine' will always be preferable to a perfectly effective engine.

Given this, I imagine that the "Nuclear Furnaces" of Imperial vessels are figuratively similar to the furnaces of old steam vessels. A steam engine can run on most combustable materials at varying degrees of efficiency, although wood or coal are ideal.

A starship engine, however, would operate at super-stellar temperatures. It would therefore be able to 'burn' (engender nuclear fusion) with nearly any light element in the galaxy. Deuterium and Tritium would work, but at high enough temperatures other elements/isotopes will burn at even greater energy levels. Even the Carbon isotopes in the body of an incompotent crewmen could fuse to provide power (should he be unfortunate enough to end up in the plasma reactor when it powers up.)

I like to imagine that these "nuclear furnaces" could, in extremis, burn nearly anything for nuclear power. That said, most fuels would be less than ideal and might land the ship in an overhaul if depended on too much. Using heavy elements, for example, might leave residues throughout the works, necesitating shutdowns and the attentions of hordes of disposable ratings armed with steel scrapers and leaky radiation-suits.

Mainly I like the 'Nuclear Furnace' style of reactor because it doesn't limit the starships' expeditionary abilities too much and because the image of massive ducts, pistons, turbines, lasers, etc all chugging away in the star-hot belly under tha labour of thousands of partially irradiated ratings, just appeals to my artistic interpretation of the setting. I like to imagine something like the pounding pistons and sweltering engine-room of the Titanic, but on a city-sized scale.

I like to imagine a ship, strapped for fuel, tossing the captains silverware and the ships furniture into the reactor in order to get a bit more power before being becalmed in space, with the Enginseer looking on in horror at the outrageous abuse of the Engine's machine-spirit.

Mostly, I would think standard light-fusion would be the order of the day. Uniformity is never a part of imperial tech, however, so there is room for nearly any type of reactor provided that the reaction is energetic enough. The main disposable limited resource on an Imperial Warship would be manpower.

In conclusion, here's a favorite concept for a new technology from General Fusion, a Canadian high-tech startup. I like to imagine Imperial engines would be similarly overly mechanical and deceptively clever. They might look like this as well. Here's the link. Hope you think this is as cool as I do. It's like a victorian-era nuclear-reactor. Moreover, I suspect that it actually might work. Keep up the good work General Fusion.

http://www.generalfusion.com/t5_general_fusion.php