Stealth in space

[Shortie]

Question for sciency types:

Okay, so whatever power your ship generates has to go somewhere, yes? And if you're not using it for your drive, it's basically all gonna end up as thermal rediation, right?

Given that, is a ship likely to be highly visible in IR, making skulking along very difficult, even at silent running? Assuming this is so, is it practical to focus that thermal energy in one direction, making you look pretty similar to background radiation from most angles?

[Admiral Valdemar]

Depends on a lot of factors, that IR signature may be too small to detect in such a wide area of space, but in a battle, it would be very noticeable.

You could always insulate the ship better, it really depends on the situation.

[Pu-239]

Well yeah install cooling coils all over the ship, and dump the heat out with the exhaust... I think

[Sea Skimmer]

Ideally you'd have a directional system that you could turn away from your enemies. You also just don't want to have that much heat, which is why large battleships and carriers are a shitty idea until you really start getting into sci tech shields and inertial compensators.

[Wicked Pilot]

Well, in orbit you will need a clear line of sight first. Then, if you approach your target from a lower altitude, the radiation of the planet/moon/whatever may mask whatever you're putting out. Just make sure to do your burns while beyond the horizon.

[Pu-239]

Or use cooling coils to dump all the heat in an insulated container of something with a high specific heat, and chuck it out. At high speeds, so to provide a little thrust. Then again, that would be kinda obvious visually, so that makes it useless.

[RedImperator]

It depends a lot on the sensitivity of enemy sensors. At any kind of meaningful distance in space, even an object the size of a Star Destroyer is going to be very hard to see. In silent running mode, you might be dim enough that you can't be spotted from a distance.

With the engines running, though, forget it. You'll be spewing hot gas at high speed out of your thrusters, and that will be visible to anyone who cares to look. It's one reason why the Star Trek cloaking device is stupid: even if the ship is cloaked, the reaction mass being spewed by the impulse drives should be a dead giveaway, unless the ship is running on intertia only.

[Pu-239]

Oh yeah forgot. Stupid sci-fi- you can't visually see a ship in deep space. However you can still use radar as a last resort.

[GrandMasterTerwynn]

Question for sciency types:

Okay, so whatever power your ship generates has to go somewhere, yes? And if you're not using it for your drive, it's basically all gonna end up as thermal rediation, right?

Given that, is a ship likely to be highly visible in IR, making skulking along very difficult, even at silent running? Assuming this is so, is it practical to focus that thermal energy in one direction, making you look pretty similar to background radiation from most angles?

Yes. The best idea would be to have a primary hull, a dead space, and an inner hull. Vacuum is a perfect insulator. You only lose energy through radiation. Sure the thermal energy radiating from the inner hull would eventually warm up the outer hull, but the overall rate of emission should be lower, except at the points where the inner hull connects to the outer hull.

Of course, this would have to be combined with a cooling system that will cool the hottest sources or heat and use them to possibly warm the ship's reaction mass. Then this warmed reaction mass would be thrown out the back of the ship with the rest of the engine exhaust. Granted the system would work best when the ship was actively maneuvering. If the ship had to lie quietly, then I'd nudge it a little closer to the system's primary and start it slowly rotating. Then I'd dump the waste heat collected by the cooling system on the 'dark' side of the ship, so it might fool a passive IR scanner into thinking we're just another asteroid. Maybe a warmer one than is absolutely normal, but no threat.

<edit>
Of course, this is for dealing with enemies that are closer in range. The intensity of the ship's waste heat falls off according to the inverse square law. A sensor twice the distance from the ship (as a baseline sensor at X km away) would recieve 1/4th of the energy. A sensor 8x further away would pick up only 1/64th of the energy, and so on.
</edit>

[Shortie]

Ideally you'd have a directional system that you could turn away from your enemies. You also just don't want to have that much heat, which is why large battleships and carriers are a shitty idea until you really start getting into sci tech shields and inertial compensators.

That's the kind of thing I was thinking of. Are you saying too much thermal energy without high tech is bad because you'd overheat , or because you wouldn't survive the incoming fire you'd make yourself a target for?

With the engines running, though, forget it. You'll be spewing hot gas at high speed out of your thrusters, and that will be visible to anyone who cares to look. It's one reason why the Star Trek cloaking device is stupid: even if the ship is cloaked, the reaction mass being spewed by the impulse drives should be a dead giveaway, unless the ship is running on intertia only.

Yeah, I was thinking inertia for silent running, just drift through their sensor zone, and power up when behind some convenient moon. (OTOH, is giong at a reasonable speed to do that for a few light-hours obvious in itself?)
But does your exhaust have to be so hot as to be blindingly obvious?

If the ship had to lie quietly, then I'd nudge it a little closer to the system's primary and start it slowly rotating. Then I'd dump the waste heat collected by the cooling system on the 'dark' side of the ship, so it might fool a passive IR scanner into thinking we're just another asteroid. Maybe a warmer one than is absolutely normal, but no threat.

This I like, and presumably it would work on any object that's radiating. Does kind of rely on the watchers being in one small area (or rather angle relative to you)

Of course, this is for dealing with enemies that are closer in range. The intensity of the ship's waste heat falls off according to the inverse square law. A sensor twice the distance from the ship (as a baseline sensor at X km away) would recieve 1/4th of the energy. A sensor 8x further away would pick up only 1/64th of the energy, and so on.

Sure, but given we're looking at stars many lightyears away today, isn't any ship with substantial power generation going on (even just life-support etc for a hundred-odd peaople could be quite a lot) gonna be fairly visible at ranges where their passive sensors could take a good look at the enemy? Or is it gonna be too small a target to easily catch unless you've got a rough location already?

[Patrick Degan]

Thermally, the ship is going to stick out like a sore thumb, no matter what insulation technique you attempt. And heat won't be confined to a narrow beam, either.

Radioactive or ionic exhaust from the drive would also be a dead giveaway. If mass-detection technology is available, the ship will give itself away because there simply is no way to stealth-cover mass.

About the only conceivable option I could see for any sort of stealth cover, and I don't think any method would cover a ship out in open space for very long if ever, would be akin to the smokescreen principle. You literally lay down a cloud in your ship's wake filled with metallic, gaseous, and charged particles (a futuristic analogue to "chaff") and pre-heated to produce a very large blot on IR receivers, to cover a formation of ships and confuse sensors on the enemy vessels for a short time period. The cloud won't persist very long so any purpose for which you'd resort to this tactic would have to be executed quickly.

Jamming and spoofing devices, radar-reflective paint or materials on the hull, might help to deter weaponry which relies on active tracking. But I don't belive any stealth method will defeat passive sensing in space.