Stealth and detection in space: Continued

[TrueGormagon]

This thread is meant to explain and discuss why stealth technology does not work in space on the whole, as it does underwater or in Earth like atmosphere via various methods. It will also debunk claims by scifi shows such as that 'powering down' will make you appear as drifting space junk in a debris field to avoid being caught by the fuzz. It will also discuss alternative methods to use, all flawed however.

I guess it depends on the specifics of the motion -- probes launched these days go months or years between engine burns.

Doesn't matter, the engine burn could be detected from AU's away and a trajectory potentially calculated. If you fire again to change course, you can be seen again. And again, the heat of the probes energy source will show up like 'the red dot ' on a white casmir sweater.

"Easily"? No. Again, if such other methods worked well, we would already have found every asteroid in our vicinity instead of being surprised when mountain-sized asteroids pass nearby. Not to mention our stealth bombers and fighters would be a waste of money.

We are detecting them over time. The asteroids would be the same temperature as space I would presume seeing as they have no power plant and have been floating there for billions of years, or perhaps those asteroids in between the sun and Earth atm are blocked out by its radiance. And I'm not talking about stealth in atmosphere, I'm talking about space. Of course stealth in atmosphere works, we see it works very well, but it itself is not undetectable. Space is very different.

The longer it takes you to reach your target, even as a drifting chunk of rock, the more chances you will be detected. If you plan to reach your target quickly, relatively at least, you need propulsion, which can be detected.

Like they've done against stealth in the atmosphere...?

Again, atmospheric stealth is not perfect. http://www.telegraph.co.uk/news/ukn...lephone-masts-can-detect-stealth-bombers.html

And a craft operating in space is very different.

I see a lot of problems with the article. One glaring example:

Our stealth aircraft have an ingenious method of making their radios undetectable: they turn them off.

Your picking at straws here, the article is meant to be taken in as a whole, other wise one can say you can achieve stealth via one means when the next paragraph down explains why you cannot use that method itself.
Radios are not the one and only problem, it is part of the article not the entire basis the article expounds on a variety of methods. However if you want to communicate you most likely going to use a radio unless some other method presents itself, and if you use it your sending out a signal, which can be detected. And I would also conclude that the power source for your electronics would show up your vessel quite nicely against the background of space, along with the propulsion.

Yes but they do not have payload on their own.

Yes, they are the payload. They are inert projectiles.

What would heat them?

I explained this already, firing them, whether chemically or electromagnetically, will cause potential detection. The projectiles will carry residual heat from the firing process. The chemical explosive will cause a heat bloom out of the barrel. A rail gun needs power, and therefore a power plant.

By space has no temperature I mean almost anything is hotter.

Slower relative to what?
There are no absolute speeds in space.

Relative to energy weapons in particular. And yes there is a limit to speed in space, C. In order to reach relativistic velocities with projectiles, you are going to need a massively long coil gun with many many segments and a lot of power.

A slow projectile relative to its source can be fast relative to its target.

Your missing the point, the question is not about the speed of anything in this matter. Its about detection.

Right, but we were discussing detection to defend against it.

Right, and detection does not necessarily = defense. It is a stage of defense, but not a pure defense. If you were tied and chained to a railway and felt the train coming that means you detected it, but can you do anything about it?

 

[Danger]

Why start a new thread about something that Russ and Mfb have already dealt with in fine fashion?

 

[nsaspook]

Your picking at straws here, the article is meant to be taken in as a whole, other wise one can say you can achieve stealth via one means when the next paragraph down explains why you cannot use that method itself.
Radios are not the one and only problem, it is part of the article not the entire basis the article expounds on a variety of methods. However if you want to communicate you most likely going to use a radio unless some other method presents itself, and if you use it your sending out a signal, which can be detected. And I would also conclude that the power source for your electronics would show up your vessel quite nicely against the background of space, along with the propulsion.

I have no idea where this thread came from but detection of radio signals is not as simple as some think with proper cloaking technology. It's very easy with todays processing to generate transmit signals that are almost undetectable by receivers unless you have the right code correlation detector sequence for the spread-spectrum encoded pseudo random noise signal that can hide in the RF thermal noise background of a normal surveillance receiver. It's not impossible to stop detect at all distances but if you know where the other sides equipment is then it's possible to adjust parameters until you are pretty close while still being in communication.
http://www.radioeng.cz/fulltexts/1995/95_02_06.pdf

 

[GTOM]

IMHO, that could have been opened in the astronomy section.

The asteroids would be the same temperature as space I would presume seeing as they have no power plant and have been floating there for billions of years

Sunlight warms them up, see the average temperature of celestials. So theoretically, according to that atomic rockets stuff, the Chelbansky meteor should have been spotted from at least at the distance of the Moon.

I don't think that a directed signal is so easy to detect. Yes stealth bombers can be detected, however theory and practice are not essentially the same.
And even if they are detected by flying between an emitter and a receiver, that is not necessary enough to guide a missile to them.

 

[vemvare]

Again, we are not using omnidirectional surveillance to guard cislunar space. We have telescopes,we have surveillance satellites and radar systems, but the former are optimized for looking at things that are very far away, and the latter are watching Earth or the airspace.

The airspace of Earth is almost a 2D-environment, a stealth bomber can keep itself under enemy radar range until it crosses the horizon. The atmosphere is also filled with gases, particles and droplets that absorbs many frequencies, and even those who are not absorbed tend to be reflected from natural formations like mountains, et cetera.

If you are pointing a (space based) telescope at a portion of the sky, there is likely nothing else there except what you are looking at. No thermal emissions, no visible light. "Stars" won't matter, apart from the sun they'll never have a cross section big enough to hide in front of.

A LIDAR-system would be strongly absorbed by the atmosphere, hence Radar is used, another bonus being that the most reflective objects in the radio wave portion of the spectrum tends to be metals, and big metallic objects are rare in nature. In space, these objections doesn't matter, and I'll simply send a massively intense burst of a wide range of frequencies, making it impossible to find any equivalent of a radar-absorbing paint.

Perhaps this thread should've been made in the Astronomy forum, titled "Detecting man-made objects in space", I sense a PM would be in order...

 

[GTOM]

Again, we are not using omnidirectional surveillance to guard cislunar space. We have telescopes,we have surveillance satellites and radar systems, but the former are optimized for looking at things that are very far away, and the latter are watching Earth or the airspace.

The airspace of Earth is almost a 2D-environment, a stealth bomber can keep itself under enemy radar range until it crosses the horizon. The atmosphere is also filled with gases, particles and droplets that absorbs many frequencies, and even those who are not absorbed tend to be reflected from natural formations like mountains, et cetera.

If you are pointing a (space based) telescope at a portion of the sky, there is likely nothing else there except what you are looking at. No thermal emissions, no visible light. "Stars" won't matter, apart from the sun they'll never have a cross section big enough to hide in front of.

A LIDAR-system would be strongly absorbed by the atmosphere, hence Radar is used, another bonus being that the most reflective objects in the radio wave portion of the spectrum tends to be metals, and big metallic objects are rare in nature. In space, these objections doesn't matter, and I'll simply send a massively intense burst of a wide range of frequencies, making it impossible to find any equivalent of a radar-absorbing paint.

Perhaps this thread should've been made in the Astronomy forum, titled "Detecting man-made objects in space", I sense a PM would be in order...

Carbon nanotubes are super absorbant in many wavelengths, NASA has a program to track dangerous asteroids, if distance is a thousand times bigger, signals will be a million times weaker, they can radiate heat outward the elliptic plane.
If they are coming from the direction of the Sun, it can even hide the flames of the thrusters.

 

[Khashishi]

What about a ship where the front is coated with a low emissivity material ($\epsilon \sim 0$) and the back is coated with a high emissivity material. The heat is vented through the back. How would you see the ship from the front?

 

[Drakkith]

Unfortunately this thread doesn't really stand on its own so I'm going to have to lock it. To the OP: If you'd like to discuss this topic please start a new thread that doesn't start off by quoting members from another thread. It's very confusing to those of us coming into this thread without seeing the other (like myself).