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Technical Design Rant

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Prinz Eugn

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Another Monday, Another Refrain from a Tired Monday Joke


I feel overly narrative-istic (narrastic?)right now. I think the fact that I spend a good three hours a day at work listening to NPR's "This American Life" at work has warped my perspective on writing for an audience. It's just a shame I'm not an inner city single mother befallen by tragedy with a handy tape recorder, or an NPR correspondent who happens to have some marginally interesting relative with a handy tape recorder forcibly duct-taped to their chest. Just know I can't get stop hearing Ira Glass's voice whenever I try to explain something.

I'm also working on getting GDNET+ back again, but something messed up with paypal, so my sick avatar that I haven't made yet will have to wait.

Anway...I'm going to take this entry to kind of lay out my artistic interest and how that relates to the cool spaceship thing.

[hr]
I think of myself as a technical artist. People as a subject have never really interested me, which I think sort of sets me apart from most artists I've known. Definitely part of it is the fact that I have a pretty strong Asperger-sy fondness for machines. Or maybe that's all of it. Anyway, I really like mechanical things, particularly weapons for some reason. It started with semi trucks and airplanes (living near a US Air Force base can take the blame for that), but soon extended to tanks, ships, and spacecraft after being exposed to movies. The Super Star Destroyer was probably my favorite Star Wars character. For whatever reason, I think drawing machines, and that's what I've gotten good at over the years.

How does that relate to the last entry?

[hr]

Fact: Battleships Are Cool


Battleships strike me as some of the coolest machines ever designed. They're some of the best examples of war machines that look like they really mean it, and they're epically proportioned to boot. Unlike modern warships, they bristle with very obvious firepower. Hell, battleship turrets alone are some of the sweetest technical designs themselves IMHO:
Battleship_Turret_by_PrinzEugn.png

Their basic concept also carries over to sci-fi as well as anything, since the a pretty common assumption in fiction is that if you're going really far, you're going to need a big thing to do it. Plus it's a handy setting that lets you fly across the universe but film in the same two rooms every week.

[hr]

Tangent on Battlecruisers


[color=#ff0000][Easily Skippable][/color]


It's kind of interesting how the coolness of the word "battlecruiser" has somewhat overwhelmed "battleship" for a lot of things, Starcraft in particular, when the actual operational history of the battlecruiser is actually pretty terrible. Battlecruisers on paper sound like a really cool idea. The basic concept is that there are three main attributes of any fighting machine: firepower, armor, and mobility. Battleship designs historically balanced the first two, then did what they could within technology and time constraints for the third. They sacrificed speed for armor in a bad way. Theoretically their speed would keep them out of trouble if they ever faced an actual battleship, which Admiral "Jackie" Fisher, essentially the inventor of the concept, subtly explained by saying "Speed is Armor." Turns out, nope. It's really not.

The basic problem is that the speed advantage gained, say from 21 knots to 25 in the case of the original Dreadnought and battlecruiser equivalent Invincible, wasn't worth sacrificing basically half the armor protection. In a two-dimensional fight the small gain in speed didn't give the battlecruisers enough mobility at all to compensate for having functionally paper-thing armor. In the Battle of Jutland, the biggest actual Battleship-vs-Battleship engagement of the war, the British battlecruisers had the alarming tendency to explode almost immediately after being hit in the turret. This happened because the armor was thin enough to guarantee a large-caliber shell would penetrate, and because at the time a ton of extra ammo was being stored in the turret and the path to the main magazines left unobstructed. A hit on a turret was therefore almost guaranteed to set off the magazine. Turns out mecha and anime villains aren't the only things that die in enormous explosions.
[hr]

Large Spacecraft Design: The East-West Dichotomy


Western Tradition


I've always thought there were interesting differences between some Japanese and western spaceship designs in my by no means comprehensive experience. Western ships (and by ships I mean big spacecraft- stuff bigger than the Millennium Falcon) of the past few decades seem to revolve around the precedents of Star Wars and Star Trek. Ships are almost of interminate size and plastered with details but always pretty linear, with little organic influence. They seem to rely on not betraying any real sense of scale to seem awe-inspiring- they tend to have the bridge or cockpit not terribly obvious if at all from the outside. Traditionally they always look very utilitarian, packed with unfathomable levels of detail but for some reason they never seem to display any obvious weaponry, which always disappointed me. A Star Destroyer or the Enterprise A-E don't show any teeth, which I think is a shame. Notice how a large proportion of the Super Star Destroyer is essentially crammed with empty detail that I like to call "squiggly bullshit.":

830px-Executor_SWE.jpg

Cool, right? Too bad you need this helpful diagram, which I'm pretty sure had to be retconned as hell, to find anything except the bridge:

830px-Executor_schem.jpg

The only time anything vaguely organic or at least not made of right angles showed up, it's alien, but even then they tend to stay consistent to the rule that ships over a certain size have tons of random detail, but very little of it meaningful. Alien ships tend to have looser rules, but they mostly look insectoid or like very angry plants.The most painfully stereotypical example of this is in the Halo series, where brave human hexagonsfight purple dolphins.

Eastern Tradition


I've always preferred the more Gundam-esque ships, which seem to hew closer to real ships, which I prefer. You can actually see the guns! That's awesome! They also tend to be more colorful, which I think creates more visual interest than the overplayed GIANT GRAY THING, though less realistic.

Take these selected examples:

magellan.jpg
The Magellan Space Battleship from the original Gundam series, which looks like a battleship, but in space. Pretty straightforward and relatively cool. Take that a couple steps into the future:

Final_Musai.jpg

Musai-Kai from one of the spinoff series (0080), which does an excellent job of being sleek and futuristic, while obviously being artificial and not a sinister grasshopper derivative. Also:Guns! You can see them!

The first 20 seconds of the following clip illustrates the scale thing pretty well (I wish I could show you a better one but they managed to block only that episode out of the 12):

[media]
[/media]

You see the mobile suit (giant robot for the uninitiated) on the right of the bridge, then you see it launch from the bridge- it gives you a better sense of scale so that even though something like a Star Destroyer is much bigger, the impact of actually having some idea of how big the ship is makes for better design. Gundam series are particularly good about being able to see parts of the ship from the bridge, and having exterior shots of the bridge to illustrate the sizes involved. You don't just shrug it off with a subconscious "it's really big," you get at least a vague notion of what that really big actually is.
[hr]

In the end, it's almost sad how incredibly intriguing this website is (mind blow alert): http://www.merzo.net/ particular for the ships of different series, which just goes to show you how incredibly vague they leave the dimensions within the main fictions. Also see if what I'm saying makes any sense while you're there since they have ships from both sides of the pacific.

I'm pretty much out of time to write, so I'll try to go into my personal ideas and biases that went into the actual design of my ship next entry. I've actually made a fair amount of progress since last time...

Note: Hopefully all the images work, I'm not quite used to the new jourrnal system. When I was growing up, we had to hardcode HTML both ways uphhill in the snow.
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I'm an engineer, so I approach these things from a somewhat different angle. There is always the "rule of cool" type stuff, but I also consider how much sense a given characteristic makes. Simply put "organic" shapes really don't make a huge amount of sense. Any time you see a tightly rounded surface or acute angle, you're seeing what is probably some wasted space. This is why most human structures don't have a lot in the way of roundness except for artistic or structural reasons (ie: Arches are used because they are both pretty and very strong).

Realistically speaking, it makes far more sense to bury the bridge/CIC/command center as deep in the ship as practicable, as putting it on the edge just makes it easy to damage. Seeing the guns is cool and all, so long as the mechanisms supporting those weapons are sensible (There are a few different perspectives, but a lot of people - including myself - think that engagement ranges in space would probably be on the order of hundreds or even thousands of miles, not the couple dozen you typically see. Thus, projectile weapons make very little sense... Unless you can propel your giant space bullet to relativistic speeds, you probably won't manage to actually hit anything. Missiles aren't much better. Excepting the invention of some kind of super compact reactor thing and some kind of high thrust engine that uses next to no fuel, Missiles would never be able to move or maneuver fast enough to actually hit anything. Though its strange to think about, directed energy weapons make far more sense (since their energy or highly energetic particle output moves at approximately the speed of light, and requires power more than fuel so doesn't require a big giant magazine or other balance disturbing concentration of mass).

I'm personally a huge fan of the RDM Battlestar designs -- they give you lots of meaningful hull detail (armor plates and structural ribs and such) while also letting you see things like guns and missile tubes and such, and also place critical spaces relatively deep in the ship where practical... Apparantly, they took a lot of the design concepts from real-world submarines and combined it with, clearly, some aircraft carrier stuff.

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I agree that realistic ships will be a lot different. I approach it from the perspective that the ideal for artwork isn't absolute realism, but a compromise between realism and aesthetics that allows for a suspension of disbelief while being instantly "cool" without extensive explanation.

I'm actually watching Battlestar right now, actually...

The command center problem is pretty classic, and I think BSG did a pretty good job of that and the stuff you mentioned. Interestingly, some later Gundam ships compromised by having the normal outside bridge that looks cool and a "battle bridge" sunken in the ship, connected by elevators (not exactly practical though).

I wonder about range, though, because I think it could go either way. You'd have to close the range to hit anything, even though detection range will be much greater. I remember Mote in God's Eye had the cool scenario with ships being so far away that even with lasers, they had to guess where the enemy ship would be since they were at such huge distances that light speed was a factor in targeting.

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A certain degree of artistic license is, of course, acceptable... particularly because these things don't exist yet (though we can reasonably take hints from naval ships and airplanes and such so long a we account for the real things being shaped by hydrodynamic and aerodynamic concerns).

Do yourself a favor and stop watching after the first couple eps of season 3, just goes downhill from there.

I remember one ship in Gundam SEED Destiny which had a conventional bridge... but the whole darn thing would sink into the ship before a battle. That's an interesting (though convoluted) solution.

A general rule of thumb is that detection range will probably be far greater than practical firing range, regardless of the weapon. However, the practical firing range for a projectile weapon will undoubtably be far shorter. Sure, a railgun will make the projectile travel much faster (thereby extending range). Lets say by the time we'd have space battleships railgun technology is capable of 4x the max they're shooting for today... that's still only 10km/s -- or about 0.003 [b]percent[/b] of lightspeed. Obviously this is just a wild guess. Anyway to hit anything with a projectile of that speed would require relatively close range or the expectation of minimal maneuvering at range. A directed energy weapon, however, relies on a more or less coherent beam of energy... its practical range would be limited mostly by your ability to aim it (since the energy travels at or near light speed your practical range is not infinite but it is certainly on the order of thousands of kilometers rather than dozens... for context it is only a few SECONDS distance from earth to the moon at lightspeed. Travel time of your typical naval shell is greater than that), and your sensors' detection range. Heck, my guess is that we'd actually design these things to be imperfect intentionally (perhaps focusable?) so that we don't risk damaging things if we miss (though we probably wouldn't hit anything due to the relative emptiness of space).

As for sensors: Yeah, idk. My best guess is that we'd initially start with a bunch of RADAR-type devices (from which we filter cosmic an environmental background radiation). We'd need them to cover the most practical types of em -- so RADAR is a given. I'm not sure if it would be practical to build an infrared equivalent of RADAR, but I'm guessing it would be useful (unless we can't easily discern the signature of a distant star from a relatively near by ship). We'd also want telescopes (probably not useful for detection) both for navigation (even the apollo CSM had a telescope used for star fixes) and to try to see your target once you've actually detected it. One RADAR in the nose or whatever absolutely wouldn't do... any armored hull would probably block most of the signal, so you'd need to place these devices - probably on or near the outer hull - in multiple all around the ship to cover all arcs, and to account for potential battle damage and such. (so complicated shapes would actually represent a near distance sensor nightmare, since you'd either need way too many sensor devices to cover all arcs at close range, or just accept lots of big/little coverage holes.

Sorry for going on so long. This is interesting stuff!

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Personally, I'm skeptical of lasers, but I'm probably biased by my familiarity with modern technology. Lasers, at least current and near-future ones, just don't do anywhere approaching the damage of kinetic projectiles. Weapons are things that move energy to a target, and its harder to put lots of energy into photons than chunks of metal. It'd be interesting to see if focusing lasers at extreme ranges is a problem... of course, no atmosphere, so I dunno.

Projectiles I think would still be useful, since they would do a lot of damage if they could make it to a target, and you can get a free boost in energy from gravity wells. In a running space battle at thousands of kilometers they wouldn't work to well, but against an enemy in orbit, they could be deadly, or at least force them to waste propellant dodging them.

Bodes badly for anybody thinking they're safe of the surface of anything though.

Sensors I know somewhat more about... 360 coverage wouldn't be too hard, but you would have to leave them on the outside of the armor (or better yet, on another ship with a high-bandwidth data link). Phased Array Radars now have very large coverage areas without mechanical parts, http://en.wikipedia.org/wiki/AN/SPY-1.

Radar is an active sensor (you're shooting stuff out there, and waiting for some of it to come back), which unfortunately means that the enemy will always be able to pick up your signal farther away than you pick up the reflection (unless you hide it well). Infrared is generally a passive sensor (just picking up whatever's out there already), so is probably a better choice. Probably the biggest challenge will be hiding whatever radiation your drive is putting out.

Man, at astronomical distances, detecting other ships is going to be a tremendous bitch, so it's plausible they can get deep within a solar system before detection, especially if they can use planets and asteroids for cover.

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Hey guys! Some great thoughts in here.

Got a few ideas about weapons and sensors. Energy weapons are not likely to be the best choice because of the energy requirement to actually damage something. Consider that you could have some very significant armour density and thickness along with heat disipation just boring a hole would be very difficult. On top of that though, even lasers disipate energy over very long distances. Plus the shot might just miss. A better beam like weapon would be high energy particles. Unlike light, particles dont disipate and will hold a focused stream for a much longer distance. Check out some of [url="http://en.wikipedia.org/wiki/Particle_beam_weapon#Tesla"]Tesla's ideas[/url] on the subject.

I wouldn't discount rail guns though. Keep in mind that even seeing those projectiles before they hit you would be a huge feat of sensor tech. Especially if they are electromagneticly propelled in a near frictionless enviroment. They would carry no residual heat. They could be shaped to avoid RADAR since there are no aerodynamic concerns. They would overall be very very dificult to spot. They might not hit a damn thing, but you probably won't see it coming.
Speaking of frictionless projectiles, one speed limit on them on Earth is airfriction and other Aerodynamic effects. Those troubles will be gone in space.

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Re lasers/DEWs: Actually, its a lot easier than most people think. The biggest limitation we have right now is generating enough power to run these things -- and theoretically by the time we'd have space warships we'd have at least space rated fission generators if not fusion... which should provide more than enough power for a limited number of DEWs. Additionally, most of the range problems we think lasers have is due to the atmosphere absorbing a lot of the energy -- thereby causing massive attentuation over distance. In space there is no atmosphere to absorb the energy... a laser will just keep on going until something gets in the way. Assuming we can't build a *perfect* laser, yes the beam would spread very very slowly over distance (causing the energy to be spread out and do less damage), but the range it would take for a beam to spread enough to be harmless would be tremendous anyway.

Heat dissipation in space is not simple... not at all simple. The only way to dissipate heat in space is via radiation, which to date has required large, fragile radiatiors (which could themselves be easily damaged). Heavy armor would help to resist something like a laser, but I imagine with enough power / the right type of beam it could be defeated given enough time. Heavy armor would also make a ship more expensive/more difficult to build and require bigger engines/RCS thrusters/etc to provide the same maneuverability (Size has no bearing on speed, but rather on acceleration). If I might reference http://en.wikipedia.org/wiki/Boeing_YAL-1: While the program was cancelled, it actually represents a proof of concept that a directed energy weapon could be built and used to effect. The problem is the current expense and particularly the limited range of the current system. Transplant that to space and you wouldn't have the range problem (The atmosphere is really quite problematic), so even at the same emitter power level you'd be able to focus more energy on target (and emitter power to recieved power would scale far better than in the atmosphere).

Regarding Railguns: Well, first of all if you want a more or less frictionless environment then you need a more or less frictionless weapon -- and for that purpose a coilgun would probably serve rather better (and coilguns have their own problems - like electromagnetic saturation and such). Lets say hypothetically that you can build it so as to have no residual heat. You are limited somewhat in shaping your projectile so the electromagnetic fields in the launcher could have the greatest effect, but ignoring that RADAR shaping is usually only effective from certain angles... so there's a problem right there. Additionally, in space I'm not aware of any particular reason why other EM bands couldn't be used in a manner like RADAR. Stealth shaping is only effective against certain bands of RADAR, so if you have a bunch of different EM DAR devices covering a bunch of the radio and a couple other bits of the spectrum (chosen based on what typical construction materials would reflect, and what is practical to build). I'm guessing the difficulty in detecting objects in space will be more about processing all the data your sensors would return and filtering out all the junk and background EM. Once you detect an incoming projectile, its fair to assume that maneuvering a bit to avoid it should be more or less trivial. So yeah, its all about seeing it coming (on the other hand DEWs are more about putting enough energy into the beam). While I'm at it: Just firing a railgun or coilgun would likely create a sizeable bloom of EMR... you can certainly try to shield it (and in fact you'd have to so you don't fry your ship's computers) but there may be some leakage (which may be detectable). Yes, the atmosphere represents a speed limitation (and a source of heat bloom) for projectile weapons, but there are a couple more: 1) It takes *a lot* of energy to propel a projectile at any significant speed... and "significant" is far higher in space, 2) There are actually limitations to the power you can put into your EM field before you start facing diminishing returns. Unfortunately, the numbers I'm seeing regarding the power requirements of even the experimental railguns around now are not in the same units as the ones for experimental laser weapons -- so I can't directly compare them -- but both are easily very very large.

Regarding sensors: That's a good point about active sensors, on the other hand modern RADARs are actually quite difficult to lock on to (since they're highly directional and they can actually operate on multiple bits of spectrum, etc)... Lets still say that we'll want to limit use of active sensors as much as practical (just like submarines usually avoid using active sonar when they can help it). Good point about hiding the emissions from your engines (maybe they can be baffled to at least limit the range of angles engine emissions are visible from... and even then the exhaust plumes would probably be detectable with the right methods). Also a good point about hiding behind asteroids and such, though I imagine engagement ranges won't be nearly *that* far, and just like land combat rarely occurs in the middle of mountain ranges we probably wouldn't want to fight much in asteroid fields (also, the asteroid field is *still* mostly empty space). Sensor returns between, say, earth and the asteroid field would be probably a couple hours old, and travel times to get out there would be big as well (unless someone invents FTL... come on physicists, give us something to work with :P)... so any info from that range would be tactically useless (and even a DEW beam would take far too long to travel that far)

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I agree, medevilenemy, about Laser weapons not actually having range issues in space. It slipped my mind that the reason for them were atmospheric effects. LASERS and particle beams then are equally viable options. Detection of these weapons is a non-issue because sensor feed back times are equal to beam transit times giving the target no lead time to maneuver. Concealing Light-speed weapons only helps avoid detection from people alive after you shoot and only helps if they wouldn't otherwise think it was you who shot them. Overall its a non-issue.

As to projectile weapons, I firmly believe that there is no reason for the projectile itself to have residual heat. No propulsion process requires friction or other causes of heat to work. The propulsion options we are talking about are EM based.

I agree there still may be restrictions on stealth shaping projectiles and that may not even be all that effective. So they will be cold, but reflective, unless made of something that absorbs radiation! oh, and slow moving. Likelihood is they will still be hard to spot, especially when moving so fast, but they will be too slow to hit reliably. Seems like a good weapon for sneak attacks.

I think sensors will have to be passive. Active sensors would be like flashing a big shoot me sign in every direction. They are likely to still be present, they would be useful for navigating asteroid fields and debris fields. They are also useful to track large numbers of enemies when your position is already obvious. As mentioned though, not a toll to use often.

I'd also like to mention something about an assumption I just noticed that drastically affects the sensors. We are use to [i]electron[/i]ics. What if we had photon based computation and signal transfer. Fiber optic lines doing computation and moving the sensor signal to hull interior can't get fried by EM. So physical damage is going to be required to break the sensors. Really though, FTL is needed to reduce the time delays here.

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@Burning Hand I more or less agree, just a couple little points: If I recall, electromagnetic propulsion can actually cause some heating via secondary effects (ie: inductive heating... variable electromagnetic fields tend to induce currents in conductive materials, thus heating them through the material's internal electical resistance)... so they may not actually be "cold" though they can certainly be cooler than current prototypes.

Optical circuitry would definately offer protection against direct EM effects, though EM would still interfere with sensor operation itself (since the basic principle isn't changing, only the hardware medium implementing it is)

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I wrote this at work and never got back to it, so it might be kind of scattered:

The ABL’s an interesting example, but that’s what I was thinking of when thinking about how relatively weak lasers are now. The basic premise of the ABL was that it was going to kill pretty much the softest targets imaginable- missiles loaded with gas, built to be as light as possible, and under a huge amount of structural stress.

However, solid state lasers backed by fusion power will be way beyond that, and I agree that they will be more or less the primary weapons. That said, how do you defend against them? Looking at some ABL stuff and missiles, there’s a few options I’ve found:
1) Reflective coatings. Don’t absorb the energy at all.
2) Ablative coatings. Absorb the energy, and then slough it off (also helping diffuse the beam)
3) Prevent lengthy contact by vigorously maneuvering or simply rotating. Spread the energy around.
Even with powerful future lasers, I think armor is going to be a problem anyway, which makes me think that there’s a possibility space combat might be sort of like 18th century ship combat, where sinking warships was extremely rare, so dismasting (essentially crippling the ability to fight, not destroying them) became the goal. Lase off all the sensors and damage the parts of the drive outside the armor would be the space equivalent.
I can’t remember where, but some fiction had either mines or projectiles cryogenically cooled so they wouldn’t emit in thermal IR.
For sensors, I think how easy active sensors are going to be to detect depends on how busy the EM spectrum is wherever you’re fighting. Out in an uninhabited system, it’s going to be trivial to know when you’re pinged, since there’s nothing to radiate. But if you’re above Trantor or Coruscant, good luck weeding out sensor pings from communications or civilian radar.

Actually, they do have Lidar, but once again, it’s an active sensor.

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Regarding the ABL: Take that thing and put it in space and it would be far more effective (which is not to say devastating)... Most of what makes lasers weak and troublesome in amosphere is the atmosphere itself -- The energy is absorbed by the molecules in the air (not to mention dust) itself, so only a relatively small amount of the initial energy makes it to the target.

1) Probably more trouble than they're worth... Wouldn't necessarily absorb all the energy, and there could potentially be energy types it couldn't reflect.
2) Not strictly absorb and diffuse the energy, but rather absorb the energy into the armor, which would itself take damage in order to protect structural components beneath. This could potentially have some use, though I am uncertain how effective it would be against a focused beam like a laser.
3) Depending on how much contact is necessary for damage, perhaps

I imagine the goal would probably be to penetrate the hull of the target, thus venting its atmosphere and killing its crew (in addition to any necessary stuff like damanging sensors / engines). Of course, internal compartments would without a doubt be designed to be isolated and with a certain degree of redundency in life support systems... really though, not too sure. Depends on how effective the weapons would actually be.

Cryogenic cooling is certainly an idea, though how effective that would be I don't know. That would also undoubtedly affect the magnetic characteristics of the material. Finally, a cryogenic material (say, liquid helium which is danged cold) would not instantaneously cool the projectile body which would likely be significantly heated in the process of being fired, and even as it cooled *some* of the heat energy would be radiated off as IR... So cryogenic cooling would probably help, but it wouldn't be perfect.

Sensors: I've been operating on the assumption that we won't have FTL for a long time, if ever, and generally sticking to technology not terribly far advanced from what we have now -- so less Coruscant, more earth and perhaps lunar/martian/other moon colonies and outposts. Even then it shouldn't be particularly hard to filter out a reasonably steady background level or otherwise distinguish it from a radar type signal. Also remember that modern (and certainly future) RADAR and RADAR like sensors are highly directional, relatively low power, and pulsed/modulated. These things make it much harder to detect the incoming energy, or make anything meaningful out of it... Though I have expect that a method to isolate sensor signals could be devised given time, equipment, and sufficient knowledge of the technology (which is probably part of why they keep changing/improving radar tech!). LIDAR and other DAR type sensors would probably be desired because they would certainly have different benefits over eachother under the right circumstances... IE: Enemy using RADAR absorbing hull coating? Try LIDAR, IR, or whatever you have... I'll bet they don't have the same coverage across all convenient parts of the EM spectrum. IR is of course the most obvious thing, as even the most efficient propulsion technologies around or in development today emit significantly heated exhaust which, from the right angles, would appear as a big IR bloom (not to mention a big colored trail if you can *see* well enough with visible light)

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Btw guys, FTL is not really that needed for intra-system travel. At 60% the speed of light you can cross from one side of Neptunes orbit to the other in a bit over 13 hours (traveler time). Also, time dilation at that speed is about 8 hours traveling to 10 stationary, which is pretty reasonable. Even at half that speed its a day to cross the system and time dilation is negligible. And for travel from Earth to mars, these speeds are plenty huge.

As for IR detection, the drives I've been looking at would be terribly obvious. The best hope we have of even achieving these speeds I mentioned are to drop nukes out the ship's ass every 3 seconds. Good luck hiding that! Even the electric/magnetic/plasma type drives are not going to be easy to hide as they leave energized trails as well, usually plasma. No matter how you shape the hull or try to cool this as it comes out, you are not going to have much success because you only have radiative cooling which as mentioned earlier, is very slow. Overall, I doubt a moving target can hide unless it is drifting.

That said, IF you were drifting into range on inertia you could be quite hard to find. There are insulating materials that could be meters thick within the hull that would allow the hull skin to drop to near 0° eliminating the worry of IR.

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Wasn't talking about intra-system travel, was talking about inter-system travel... and moving at any velocity at which time dilation is significant is, I think, undesirable. Also, we don't currently have a form of propulsion capable of even 0.1c let alone 0.6. Probably the most promising thing in development right now is VASIMR (which is still pretty cool). Sure, its possible that in, say, the next hundred years or so we could have propulsion capable of conveniently high speeds, but unfortunately I doubt it.

I don't know why people like the whole drop-nuke idea so much. Its a horrific idea. For one thing, The ship would need to be pretty massive to carry all the nukes, but ignoring that the back of the ship would still need to be very very robust so as to not simply get vaporized. Additionally, the ship would probably need a fairly robust internal structure to survive the force a nuclear explosion would impart. And lets not forget that most of the energy of that nuclear blast would not go to any particular useful purpose... it'll just spew tremendous amounts of radiation and tiny radioactive particles at high speed every which way. Sure, it could probably get us up to a nice high speed, but its a really crude brute-force approach to the problem.

As for cooling: yeah, even if you can manage to keep the IR emissions from the ship relatively low, the exhaust from any forseeable propulsion system would give of lots of IR, possibly a noticeable magnetic field as well depending on the amount of exhaust/degree of polarization/energeticness/etc. The best you can probably do while actively propelling yourself is have a ship shaped in such a way so as to limit visiblity of the exhaust (via the ship blocking it). Though to be fair in space once you're at a desired speed and on the desired course, no further propulsion is necessary except for course adjustments/deceleration/etc.

Lets say you are drifting... there is no insulating material in existance that would completely prevent all IR emissions... Best you could do is use liquid helium or something as a coolant, but it wouldn't last forever. Perhaps heat could be channeled to specific radiators in order to try to reduce IR emissions from other angles, depending on orientation/etc... but yeah, the best you could practically do is try to limit IR emissions... you'd still most definately be detectable, but perhaps not as easily. And of course having hypothetically 0 IR emissions wouldn't do the trick either, as then you'd be an IR hole in space where there would be at least some radiation expected from stars/other bodies/etc.

Clearly, stealth in space will be rather complicated if even possible. (oh yeah, also, no windows in our hypothetical space warship... light would escape. better to have an array of cameras on the outside feeding to screens)

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Totally agree with most of that. Though to be fair about time dilation, it really isn't that bad until its really high. Ships on a 8 year tour of service according to ship time but 10 passing on earth is significant, but hardly "everyone you know died thousands of years ago" as is the cliche. Also, ORION drives (nuke dropping) is quite crude I agree but it will get you to at least 0.1c. VASIMIR and the other ion drives are meant only for interstellar travel and accelerate very very slowly still requiring you to have a solution for high delta-V.

Stealth though, definitely going to be hard to do. (unless you hide the ship in some future-tech multi-band cloak)

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Sorry, forgot to check this for a couple weeks. VASIMR isn't really meant for interstellar travel, I think, but certainly interplanetary travel. You either need to have a solution to help get you up to a good initial speed, or have a lot of patience. I figure a bunch of small rocket thrusters (of the most efficient sort available) should be manageable to pick up some speed without breaking the bank in terms of fuel size/mass. VASIMR should also have much greater thrust than the existing ion engine designs (though still only a small fraction of rocket levels). Note that the maximum propellant speed, and thus the theoretical maximum ship speed under VASIMR or other electric/electro-magnetic thrusters is significantly higher than rocket power (assuming you have the patience to let it accelerate)

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Ground based launch methods could achieve high velocities even without rockets, then VASIMIR could be used once in space, though high delta-v maneuvers are still hard.

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