For the purposes of this scenario, a rogue trader with a cruiser class vessel encounters a world roughly equivalent to modern Earth. The cruiser has 5,000 well drilled and trained troops on board and they're equipped like an upper end IG unit with extensive support. The rogue trader also has a small cadre of Ministorium preachers and missionaries as well as a small Adeptus Mechanicus exploratory force consisting of a magos and his retinue. The trader has trade contacts with a number of worlds back in the Imperium.

How does the rogue trader profit from this situation?

simple, he starts WW3 and then sells advanced weapons to all sides involved. instant profit.

One way would be to monitor the planet from a distance for a bit - see what and how it operates, maybe insert a few covert inflitrators and decide if there is anything unique and or valuable on the planet. If there is a limited amount of this - resources, technology or similar - either make a grand "smash and grab" raid taking what he or she wants fast and hard or use iflitrators to buy or steal it covertley.

I would think a Rogue Trader is happy to work in the long term given his likely access to anti aging drugs/equipment.

If I were the Rogue Trader, what I would do is this...

Drop into orbit, announce my arrival and call upon the world to rejoice that it has re-joined the great Imperium of Man... Behold, we bring you the light of the Truth Faith of the God-Emperor and renewed trade and contact with the rest of humanity. Next we wait for someone to reply favorably and then land with the missionaries and a sizable honor-guard. While the missionaries start their work converting the population to the true faith, I set up trade talks with our host nation (and their neighbors, friends, allies and - if possible- enemies). Do my best to trade my shiny beads for their gold and jewels, then leave the missionaries behind while I run back to the Imperium for more beads. Repeat that run a few times, bringing back more missionaries and hiring additional troops with the profits.

With luck, after a few profitable runs I can announce a new world returned to the Light of the Emperor. If something goes wrong, the extra troops are there to form a beach-head while I call back to the Imperium for an invasion force. With luck, I can at least have enough local allies to hold out on the ground for the generation or two it will take the Administratum to dispatch a pacification force.

Somehow I doubt that the citizens of a farely advanced human civilization will get down on their hands and knees when greeted by such a self-proclaimed conqueror as a Rogue Trader. Most likely they'll greet him with extreme suspicion and demand his intentions. Remember that to have surivived and even prospered in the lawless regions of space without any outside help, the humans of this planet will likely have a shoot first and ask questions later attitude. They'll probably forbide him from any landings for years while long and ardous discussions on the saftey of trade with the for all reasons alien visitor happen between the many nations of the planet.

Now I know what your all thinking, that this Rogue Trader is one of the most powerful human beings in the galaxy and if he wants on the planet, he'll likely get it. Wrong. First even with todays technology we could detect a large power source like a space craft entering our solar system. Add to this that the world has most likely lived under the constant threat of instellar invaders, and the moment such a vessel enters they're space, they will begin mobilizing military forces. They'll also likely have treaties to drop all conflicts once a threat like that appears. If the Rogue Trader moves into orbit, they will attempt to destroy his vessel. While today we have very few weapons, other than experimental stallelite surface to air missiles, capable of harming objects circling our planet, it is certainly within our technological capability. If this Earth like planet has indeed survived long enough to be discovered by the Rogue Trader, the likelyhood that they have created our modified their own weapons to meet threats from space is high. Not even a battleship can stand up to thousands upon thousands of multimegtan nuclear warheads. Neither can the ship fire out of the range of the warheads because its own weapons cannot affect the planet in any signifigant way.

The Rogue Trader could try the ancient and unreliable technology of teleportation if he's willing to risk losing some of his own men though he'd still be detectable by the indiginies. From then on he would suffer more casualties as his men are homed in on and assualted by massive amounts of force, all while either trying to achieve a objective or retreat through teleportation beacon.

Also the idea that these Rogue Trader goons will be immune to damage is absurd. Even if the planets occupants threw nothing but stones at them, the sheer kinetic force would be enough to pulverize a man in his otherwise undamaged armor. You could also take that fact that the world has survived this long without being exterminated by a hostile galaxy and allow them to have made total modifications to the standard armament of a typical soldier. If they have faced Orks or really any opponent that is superior to mankind in strength before then they will have switched to heavier caliber small arms powerful enough to harm them. It is certainly within modern armies potential to do so only there is no need do to the fragileness of the average human being. However because they live not within reality but in the dark future of 40k, nearly every civilization, including any fledgling human independents, will be looking for the best heavy hitter they can get for their soldiers in order to give them a chance at surviving.

Now lets say the Rogue Trader has some elite form of soldier like the Secutors or Space Marines. Even they will be vulnerable to harm. Last time I checked these guys are still vulnerable to heavy weapons such as hand held missile launchers and two person team autocannon. If so then I doubt they will do very much harm against the human military they are facing. Add to this the fact that even a powerfull Rogue Trader will find it almost impossible to keep more than a single squad of such forces on hand permenantly, and they may contribute very little to the conflict other than perhaps guarding keep personal.

I really don't think the Adeptus Mechanicus will give the Rogue Trader any signifigant advantage over the Terran Military Forces. You really can't treat the tech-priests like cyber punks if know anything about 40k. They litterally spends hundreds of years deciphering the use of unfamiliar technology, so it would be very unlikely if they were able to iinstantly influence a cultures hardware that has developed independently from the Imperiums for thousands of years.

I think we all need to step back and realize just how rare an independent Earth-like human civilization is out amongst the bloody stars. These people have not only survived but overcome the alien horrors of their world and are starting to prosper. They will likely be of similar siege mindset to the worlds of the Imperium only tougher because they have no one else to rely on. They may have our technology level, but they will use this advantage to the utmost extreme. Every technology that could possibly give a soldier an advantage today, no matter how unnecessary, will be utilized, perfected, and mass produced. The world may have already encountered many hostile xenos and even other human raiders. They will resist subversion by any outside force, because to them even a fellow human being like the Rogue Trader has the potential to be an enemy. To give an example of how paranoid they may be lets say Old Joe the homeless man disappeared for a day only to return the next. Sally the barmaid who usually brings him scraps out of some semblence of kindness notices this. While many people on Earth today would ignore or forget this in the hustle and bustle of their day, Sally reports this immediately to the police. They respond swiftly, in full gear, and brutally beat Old Joe into the pavement. Next he is hauled out the PD station and interrogated for hours. Whether he has an alien parasite in him or was just lost for a day doesn't matter, only the possibility the worst happening is considered.

You have many good points LordMunchkin, but I disagree with a major part of your argument. The planet you describe is not really like our own, you seem to imagine a resilient planet which has battled off the horrors of the galaxy with current day tech.

In the gigantic proportion of the galaxy it is entirely within the realm of possibility for a planet at current day earth’s tech, culture, and principles could exist out side the imperial light. This cut off human world could have entirely forgotten humanities origins (they might have theories, they might even believe humans are native), and never had contacts with xenos. This isolation could be caused by the sheer size of the galaxy, or if you really want to be sure, it could have been in a warp pocket for Emperor knows how long. A good point for my argument is the number of feral worlds you find in the galaxy, these worlds managed to eek out an existence despite horrid tech levels.

You can work with the model of earth you wish, but in my model the planet would be entirely ignorant of other species and other humans (or at most of vague legends no one is sure of). In this situation the Rogue Trader has a massive advantage. You can imagine the havoc that would occur on our world if a several km long ship appeared in orbit and said “Hi! I’m from a massive empire that spans the galaxy… how are you doing?”. Crazy cults would spring up in a heart beat, governments would rush to establish relations with the galactic empire, and we would find our perception of the universe changed over night.

No government would be ready for the scenario (barring the most insanely paranoid) of humans visiting us from afar on massive inter stellar ships. The Rogue Trader would have ample opportunity to exploit the chaos.

darkstar952 said:

How do you start World War 3? Which weapons will you try and sell them? Why would they buy them? If the pseudo Russia and pseudo US go at it full scale, their societies won't be around to by weapons and the survivors of the nuclear exchange will be busy trying to survive.

Lord Munchkin makes valid points in general, but some of them don't apply to this world. They only aliens they're familiar with are on movies and TV and are either friendly or defeated by the plucky heroes by the final frame. They're in the boondocks, they've lost their history in some catastrophe or planet spannign war and have managed to climb back up to roughly early 21st C levels with roughly equivalent nation states. They have a few, but only a few psykers (most of them are frauds) and don't understand the warp at all.. The galaxy has roughly a 100 billion stars. More than enough for one to fall through the cracks.

Modern earth telescopes are sensative enough to detect the space shuttle firing its engines . . . in the orbit of Pluto. As this is a Rogue Trader cruiser not a Dark Eldar raider or Inquisition null ship, it isn't stealthy enough not to be noticed when if anyone's looking in it's direction when it exits the warp or fires up that huge plasma shooting reaction drive. Nor are the rogue trader's soldiers invulnerable.

The theoretical Rogue Trader could try what the British used to do in India during the Raj era: set up a local potentate with power and wealth, make him a puppet regional power, then incite conflict amongst his enemies so that they wear themselves out fighting each other and steam in in the aftermath seizing power. Not sure how it would work on a planetary scale...but the model is similar in many ways.

A Rogue Trader of the 40k universe with the forces described arriving in modern earth would not have much in the way of conventional military power compared to even a tiny nation, but he would have certain advantages. A ship, for one thing, that would really be immune to anything earth could throw at it. OK, we've got nukes, but how do we get them into high orbit? Yes, the US and Russians are capable of shooting down low-orbit satellites, but I'm not aware that we could do much more, short of arming the space shuttle and sending it out to certain destruction against a 5km ship with enough firepower to destroy whole cities.

It's a very interesting question, because each side has advantages and disadvantages. The Rogue Trader can rain death from the skies presumably for months, but won't have enough military might to do much else, whereas Earth would be at the ship's mercy, but able to prevent landings and kill any invaders.

No doubt this is actually a classic scenario for the Imperium, and Rogue Traders in general. It's actually reminiscent of the "Death of Captain Cook" situation. Technologically advanced ship arrives with small crew for purposes of trade/military invasion. More technologically primitive indigenous culture lacks the high-powered weapons, but still kills the captain when he gets cocky/careless and assumes that he can just roll in and do what he wants.

I'd just like to prove why a civilization of Earth's Tech Tier would have some experience dealing with interstellar hostiles. First the world has prospered enough to emerge from the state of chaos brought on from the Age of Strife. If they are anything like Earth, they have also spread around the globe, becoming the dominate species on a initially foreign world. Next is the unavoidable fact that this world exists in the galaxy of Warhammer 40k. This very fact means they live in a galaxy home to numerous alien civilizations and lifeforms, many not discussed in the fluff but hinted at because they are but microscopic empires compared to the Imperium. However it is almost impossible that this world has not been exposed to some Xeno influence, no matter how benign.It could be some alien ruins on their southern pole or strange transmissions picked up on edge of their solar system, the point being that they'll know they're not alone. If you want to have this discussion be in a non-40k galaxy then sure the human civilization is likely none the wiser of all the aliens living just next door. This being 40k however means that the galaxy has a distinctly "lived in" quality that permeates through all aspects of it.

This whole discussion leaves out the possibility that they did not arise from theri former state of primitacy through slow deliberations of knowledge like on Earth. Rather they could have uncovered former ruins of their own initial colony and are slowely deciphering ruined data matrices uncovered. This is scenario is much more likely than them just relearning the technology for the end result would appear nothing like modern day Earth. Between just trying to survive and raising the foundations of a civilization, the many influences on this new culture would create distinctly alien culture. Only by having a reference point to build off of, a key if you will to forge this knew world, will you get something similiar to Earth. Add this all to the distinct possibility of Xeno contamination, and you get a world far less ignorant than Earth.

I'd also enjoy addressing the question of affordibility in all the militant options of deaing with interstellar visitors. When entering a conflict with such a large threat as that, you have to realize that it will not be one single nation bearing the burden of financing it, but the entire planet's resources. It won't be a question of cost but rather of what they can build. It is certainely feasible today to build nuclear impulse missles to strike objects at the edge of our solar system, only beyond one goverments ability to pay for. If you modified those rockets to lets say be hidden in a heavily shielded silo on the Moon, it would be be a fairly simler matter to catch the foreign vessel by suprise and destroy it in the resulting ordinance.

I highely doubt a Rogue Trader could get through to the people by placing a puppet state on planet to exert his will. Time and time again has shown that in history of our own Earth, the indiginies of a land do not tolerate puppet states, no matter how well supplied, the only end result being armed rebellion. In the end I believe an experienced Rogue Trader wouldn't risk open war with an entire planet, unless it was completely unarmed.

LordMunchkin said:

Hmmm...not sure I agree. The cynical tactics adopted by the British in India enabled them to subjugate a vast population for nearly two centuries. In the timescale of 40k, that would allow the Rogue Trader plenty of time to bring up the big guns of the Imperium to support his attempts to acquire the entire planet.

I agree that a sensible Rogue Trader wouldn't risk war with an entire planet - bear in mind the British were never at war with the whole of India. Rather, they simply picked certain rulers to deal with, gave them technologically advanced weapons and set the ruler's other enemies against each other, leaving the puppet ruler as a dominant regional power who could step into the vacuum.

How would you do it with Earth, say? Perhaps pick a powerful nation, and pretend that the Imperium has a similar governmental structure, and that the Imperium particulalry sympathises with that nation. So maybe go to the US and lie, saying "The Imperium is a democracy. We are shocked at how undemocratic the Earth is. We will support you in order to ensure a truly representative world government that the Imperium can deal with."

Or perhaps go to China and lie through your teeth. "The Imperium is Communist. We are startled at the way communism has stalled on planet Earth, and are here to give you the resources and technology to ensure the spread of Marxist theory across the globe."

Then stir up dissension and hatred amongst other nations using hidden agents - if the Rogue Trader is backing China, perhaps inflame US/Russian rivalry until the bombs start flying. The two great powers would wear each other out, and China would sweep in after the event, with all the technological might of the Imperium behind it.

Incredibly simplistic, I know, but these sort of tactics - highly adapted to regional religious/political scenarios - genuinely work for imperialistic powers.

Divide and conquer. That's how I'd roll as a Rogue Trader!

1) Yes, a planet rediscovering part of its past through ruins and artefacts is a more likely scenario. It isn't this scenario however.

2) A planet can easily be undisturbed by all the races in the galaxy.

The Imperium is by far the largest politcal entity in the Milky Way. It covers more than a million star systems.

There are over one hundred billion stars in the galaxy.

That means the Imperium occupies one out of every hundred thousand star systems and it the dominant power with the greatest number of holdings and reach.

Galaxies are big, so big that it's hard to grasp just how huge they are even if you can grasp the math.

And this is before we factor in the difficulties of travelling through the warp and how difficult it can be to reach certain areas.

This is also why Rogue Trading is a fairly secure vocation. There's a lot out there waiting to be found.

As it seems a controversial point I'll define what I believe to be "Earth-like" and move on from there:

For the purposes of this I'm going to assume that we're dealing with a planet which was cut off from the rest of humanity during the age of strife and for the last 10,000 years has remained isolated and by accident or design untouched by external forces such as xenos or chaos. Terrible war has devestated the entire globe and any knowledge of technology or the external universe has been forgotten and now re-invented or discovered.

Modern science and archeology point with increasing certainty to extra-terrestrial settlement of the planet and some space probes have photographed indistinct objects in the outer planets which may be ruins of a previous "pre-cursor" civilisation which survived the terrible events of pre-historic times on the world, these discoveries have largely taken place in the last 30 years and no full international effort or will exists into investigating them, although it's hoped to send that the first mission to another planet will involve an archeologist, this is 10 years off at least.

About 100 years ago basic radio technology was created and the technology level is pretty analogous to modern day Earth: If we have it, they have it, if we haven't gotten around to inventing it yet, neither have they. There are some hottly contested radio signals which indicate that there may be intellient life out there, but they are faint and some scientists believe they are merely some form of stellar process astrophysics does not have good model for yet, possibly pulsar reflections.

Politically the world is not unified, it is split into over 200 seperate and frequently warring nations, there exists a superpower and a number of major economic and military powers which normally co-operate on good terms maintaining some illusion of world peace despite a number of long-running conflicts occuring throughout the globe. Nuclear weapons exist and a number of powers possess them, however they are maintained as a deterrent rather than a weapon of regular warfare. The world has never in living or historical memory had contact with intelligent life from another planet and the only co-herrent plan or treaty about this was drafted 50 years ago by a number of bored beauraucrats at Unified Nations and forms an agreement that no nation shall attempt to speak on behalf of another nation to visitors from another planet. It is not known if anyone have ever or will ever take this agreement seriously.

While psychic phenomenon have existed on the planet for time immemorial they are very very rare, perhaps due to the same reasons the world has been isolated for so long. However in the last two generations the level of psychic activity has risen dramatically and there is some serious scientific research ongoing into this new and poorly understood phenomenon. In some nations anti-discrimination laws exist to protect the psychicly gifted, in others psychers are worshiped or burned at the stake, sometimes both. Due to this psychic retardation on the world Demons are monsters from legend and not believed to exist, this may well change.

Captain Ido and his vessel the Prosperous Endevour follow a new and apparently stable warp route to a previously uncharted portion of space. His navigators warily tell his a number of ancient warp storms have cleared in the last century and with some pretty clever navigating they've worked out a way through to this Earthlike world. His auspect officer informs him that there are some faint and tenuous signals which suggest intelligent settlement on this world. Ido does not know what to expect and so packs accoridngly: troops, trade goods and missionaries. He also makes sure the Navigators are making a map.

Both sides see the other coming: the Prosperous Endevour 's auspex's pick up radio traffic from the third planet and the auspex arrays are able to conduct a long-range scan of world well in advance; meanwhile the planet's telescopes and radio dishes quickly spot and identify this new intruder to the solar system. Signals are relayed and a simple communication system is set-up by the time the Properous Endevour arrives in high orbit.

If Ido is smart (or at least if I'm playing Ido) then what he does is this: The first visit is brief, no more than a few months. Cultural information is exchanged, sticking to the more palatable versions of imperial history and culture if possible. A number of visits are made to a number of different nations, in each copies of imperial texts and propaganda are left, preferably in the local language, however if not then in high and low gothic, local translations will exist by the time they return. No major trade deals are offered and little technology is exchanged, a few token deals are done, either with the blessing of the mechanicum or covertly and unofficially. The idea that there is an imperium, that it does not seek to conquor but to trade, in all dealings the trader should act passively and avoid appearing agressive or militaristic. A high orbit should be maintained and point defences constantly readied in case any nation gets the idea that a few swift nukes will keep their planet a secret for another 10,000 years. At all opportunities knowledge about the world should be gathered whilst controlling the information the planet recieves about the imperium to the positive aspects. For this reason the number of crew allowed to the surface or in contact with the natives should be minimised.

Eventually the ship is readied, trade goods stowed and a number of volunteers from the planet should be taken aboard to act as ambassadors for their world to the imperium.

Ido departs for Imperial space and en-route has his adepts compile a full account of the world, its location, its cultures, its tech-levels and its politics. He sells this, along with the ambassadors and trade goods he picked up to the highest bidder on his return to the imperium. He then contracts out his vessel to this bidder to provide passage for a larger "first contact" voyage, with either more missionaries, trade goods or soldiers depending on his client's whims.

I might be a little mercenary in my approach, but the opportunity to be rogue trading, blockade running, entrepid explorer with a side-line in being forced to do the right(ous) thing in the Grim Dark Future of humanity is something I'm really looking forward to.

Here is how I think a Rogue Trader would go about establishing domination over the earth, or a nation just like it in terms of technology and culture. First the Rogue Trader makes contact, if the world is anything like earth, likely they will be in awe of people coming from space and for the most part likely willing to be friendly and fearful of the space people's power. Likely the existence of extraterrestrial humans will have a lot of philosophical, scientific, and religious implications for these people - it certainly would for earth. Cults may string up, religious debates may occur, scholars may try to fit this into their models of the past. Anyway, the first several months go by with a cultural exchange, with each any language barriers being addressed and with the Rogue Trader trying to learn as much about the planet as possible. Perhaps Imperial Priests could make tentative attempts to reach out to the major religions of the planet - saying that God is really the Emperor, that Jesus was a manifestation of the Emperor and Jesus' sacrifice was a representation of the Emperor's sacrifice for humanity - or some equivalent story based on the religions of this pseudo-earth.

So, then trade begins. The Rogue Trader will of course try to get as much as he can for at little as possible. The Rogue Trader will buy products from the earth that are relatively expensive to the Imperium with goods or even technologies which are cheap for the Imperium. If this extremely profitable trade continues and the earth people seem fairly receptive to Imperial ideas and willing to be exploited economically, then there likely wont be any need for an outright conquest at least not for a while. Of course, at some point the Rogue Trader is going to want the people of this planet to do something that they aren't going to want to do - like give up religions that are incompatible with worship of the God Emperor, to give up technologies that are heretical, or to reframe from making comments that are against the interests of the Imperium. Lets assume that trouble of some kind arises and the Rogue Trader needs to exert military might.

Well, it is likely that the Rogue Trader already has contact with the world's major powers and with its major corporations as well. It may well be the case that many of these powerful groups on the world are profiting from their relationship with the Rogue Trader, especially if they have exclusive access to certain forms of advanced technology or goods. These powerful nations and corporations may well be in the minority in their benefits - perhaps most of the world is suffering because of the Rogue Trader - but the power of the world will likely rest in the hands of the wealthiest nations and organizations just like on earth. The Rogue Trader could reduce every major nation on the planet to the stone age in a matter of days with lance strikes if they so desire, of course, this wouldn't be profitable nor would it allow real occupation. The Rogue Trader doesn't have anywhere close to the number of soldiers to occupy the planet. This is what the wealthy nations of the world are for.

A small show of power is likely all that would be required to bring the major nations of the world to heel - like destroying a mountain with a single lance strike along with the warning that this mountain could have been a city of millions. The wealthy industrialized nations will capitulate, they will have to. Those that do not will see their cities, power plants, farms, military bases, etc. destroyed one by one until they are annihilated or capitulate. Of course, poorer nations will be harder to bring in line, along with numerous civilians especially those with strong ideological or religious reasons for opposing Imperial rule. But the Rogue Trader doesn't need to put any troops on the ground, the militarily powerful nations will keep the poor ones in line. The equivalent of the US, European Union, China, Russia, etc. will all be obedient to the Rogue Trader - if one of those nations refuses then they are made an example of. A few well protected advisers will be left to keep an eye on presidents and prime ministers of the servant nations and make sure that they rule in according to Imperial interests - but for the most part nobody from the Imperium needs to actually be on earth - so comparing dragon skin with carapace armor is moot. As the nations of the world become more resigned to the idea that they are under control the Rogue Trader can make more oppressive demands of the people. Sure, there may be a lot of brave people willing to resist, but that isn't the problem of the Rogue Trader, its the problem of the puppet rulers to fight the guerillas. If the guerillas start getting too successful, for instance if they manage to mass an army or take over a city, then that army or city is turned to ash from orbit.

Edith The Hutt said:

Cynical Cat said:

Perfectly true, but it's a big sky. The argument that 'our' astronomy technology is good enough to spot a power source that far out presupposes that it's pointed in the right direction. I realise you did mention this in the quoted section above, but it is a very important point.

If I were the rogue trader in question, out to find new and profitable worlds for the Imperium, I'd remember that there are some very smart, very unfriendly people/xenos out there, who probably wouldn't take it too kindly if I were to drop in with a pocket warship and a flag to claim the place for the Emperor.
As a result, I'd be very tempted to shape my SOP when entering an uncharted system around the following assumptions: the place is inhabited by paranoid, trigger-happy entities or artifacts; with at least the resources and sensor coverage of a Sector Fleet base. As a result, I'd have dropped out of warp just inside the local Oort Cloud (well, the inner Oort Cloud, anyway- I'm not punting in from almost a light-year away using STL drives), and made a low-powered insertion towards the biosphere, keeping my emissions as low as possible. If possible I may even try and come in from way out of the ecliptic, even if the best models I've seen for both hyperspatial travel and good, old-fashioned real space rocket science suggest that that would be far more energy-intensive, and probably dangerous (in terms of increased risk of component failure as I leave warp).
Now, because I'm making a long, slow, coasting orbit in towards the planets, I have plenty of time for my passive instrumentation to gather a load of data, including intelligence from the emissions shell of our hypothetical 'Earth' (probably ranging from the dominant language groups, religions, militaries and cultures through to Big Brother and Neighbours), and the locales, vectors and probable compositions of any significant planetoids (for orbital strip-mining). That time can also be spent preparing local language primers, analysing the local political situation, and having the Missionaria Galaxia contingent work up which local legends can be twisted to fit the Imperial Creed.

As a result, by the time my ship is spotted, I will hopefully have made sufficient preparations to ensure I can turn a profit no matter what (ideally, peacefully bringing it into the Imperium, but worst case scenario being the destruction of every major urban and military centre on the planet with orbital bombardment). If I'm unlucky, and spotted while I'm still far out (say, round about jovian orbital distance), I still have the option of powering up and opening fire, as planets can't dodge. However, I'm more likely to go for a zero/50Mm intercept with the planet, and announcing my intention to trade on every major communications band I detected on the way in, in every major language. At the same time, I destroy or disable every weaponised satellite that comes into range as a 'safety precaution', announcing that I'm doing so as well. That means that anything launching to attack me is coming up from the bottom of the gravity well, and so is an easy target.

I offer to trade suspensor tech to the two richest/most advanced political bodies, and las weapons to everyone (nothing orbit-capable) (selling for gold, or refined metals, and also more fuel). I leave technical advisory staff with everyone who buys from me, and missionaries with them as their 'personal chaplains and confessors'. I then go, and spooge about the asteroid belt, looking for the most likely locations for profitable asteroids to mine, grab a hold full of samples, then head off back to the Imperium.

I return, at the head of a fleet including representatives from an Imperial mining conglomerate (operating under license from me, as I staked my claim to the profitable asteroids and leased them the rights to mine it, for a percentage), such as Allied Imperial Minerals, and troopships filled with 'Imperial Guard' (probably just a more disciplined than average mercenary company), lead by someone claiming to be the Imperial governor for this newly-discovered planet. In actual fact, they'd be another employee of mine, unseen by the locals until then. I apologise to the locals, say I there was nothing I could do, it's Imperial law, I could lose my Charter and Letter of Marque, and so on, then offer to try and negotiate terms so it doesn't come to a war of conquest. Essentially, I pretend to be on their side, 'negotiating' with the 'Imperium' for reasonable terms that don't include a war of compliancy. Since the 'Imperial Governor-designate' works for me, I'm effectively tricking the locals into swearing fealty to the Imperium on my terms.
Anyone who doesn't want to 'negotiate', or tries to resist the generous terms I'm able to 'force' the 'Governor' into 'offering' will find one of their cities hit by a demonstration orbital strike, followed by the 'Imperial Guard' moving in to restore order. Any countries engaged in hostilities will have a major military base hit by a demonstration orbital strike, with the 'Imperial Guard' deployed to act as a peacekeeping force.

By the time I leave again, I should have at least one hexathedral set up in orbit, along with several regiments of 'Imperial Guard' to act as the 'Governor' and his personal soldiers, every country should have signed up to Imperial rule, one of the conditions of which is the free an untrammelled movement and activities of missionaries (acting openly and in force, this time) on pain of orbital bombardment. Until the missionaries have fully converted this 'Earth' to the worship of the Emperor, I can just have ships arrive every so often to pick up the 'tithe', and once they're done, I announce their existence and compliance to the Administratum, and try and get a minor member of my line chosen to act as the Governor

Just as with the parent thread, the problem arises with the interface between reality and the fantastical world of WH40K. For the record, a space-craft of the size described would definitely have an EM signature large enough to be easily picked out, even with a careful approach you'd merely make yourself seem less threatening, perhaps. You're right that they'd need to be looking in the right place but down here on Planet Earth, we look everywhere with many instruments all of which are capable of spotting this theoretical approach, so it's pretty safe bet you'd be seen and tracked with interest whilst months away.

Returning to the WH40K universe, however, we are talking about a world with the supposed tech-level of 20th - 21st C Earth (by which I assume we mean the highest level of technology). What happens depends on the Rogue Trader but with the resources described, he's in no real danger unless he sets foot on the planet and if he's aggressive enough he can simply level the planet from orbit, let it cool while he looks around the rest of the star system, then send down troops to mop up any remaining resistance and assess the ruins. There really wouldn't be anything that such a planet could do about it besides trying to bargain with an unconditional surrender. From orbit you could 'drop' your rubbish out of the space vessel and watch it devastate large areas of planetary surface in 'kinetic kill' fashion, nevermind what your space-to-space weapons might do to atmosphere and planetary infrastructure.

My Rogue Trader is basically a pretty nice person, as Imperial nobility and Rogue Traders go, anyway, so she'd probably seek to trade for technology that the Imperium no longer has, negotiate for the Missionary to be able to set up a mission and address the planetary populace and for the Explorator to study the elements of technology that are interesting but fixed (hydro-electric plants, nuclear power stations, etc, etc) whilst having the Arch-Militant assess the military readiness and ability of every power on the planet so they can brief the Imperial Guards and, if necessary, Space Marine contingent that we carry on our vessel. Ideally the world is receptive enough to the missionaries that she can consider her religious duty discharged, they are happy to trade and exchange information, so she can make a profit and their military is not gearing up for any sort of strike against her and her expedition. Worst case scenario, she will fire on major population centres, from orbit, then demand a total surrender underlined by her willingness to keep firing on population centres until there are none left or a surrender is offered.

I can not believe that this topic still has such amount of spunk in it.

In the meanwhile I have read this great novel and can recommend it to anyone interested in such form of the close encounters:

http://en.wikipedia.org/wiki/A_Deepness_in_the_Sky