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2023-11: Warosu is now out of extended maintenance.

/sci/ - Science & Math

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1896596 No.1896596 [Reply] [Original]

would this work?

>> No.1896607

good idea.
but diffraction of IR around edges of heatshield might be visible.

>> No.1896601

Yes. Interstellar background radiation is 3 Kelvin, so it would not be detectable thermally. If it was close to a star you could see light reflected off it, but further off, visible light will be too dim to be useful.

Its only stealthy on the side the cooled plate is on.

>> No.1896611

>>1896607
how would i do that?

>> No.1896617

>>1896601
what if there was a screen on there displaying whatever would be behind it? would that be perfect stealth in space?

>> No.1896625

>>1896611
stop that, i mean.

>> No.1896634

>>1896625
>>1896611
Make the heat shield bigger and reduce any gas leaks.

>> No.1896655

just make sure not to occlude any stars or planets

>> No.1896656
File: 12 KB, 426x304, stare.jpg [View same] [iqdb] [saucenao] [google]
1896656

>>1896596
>AC
>air conditioner
>implying there's air in space

>> No.1896666

>>1896656
AC = a common name for the heat pump

>> No.1896684

>>1896666
And where will the heat go in space?

>> No.1896687

is there any heat pump that can get something down to 3 kelvin?

>> No.1896704
File: 1.37 MB, 3032x2008, eps.jpg [View same] [iqdb] [saucenao] [google]
1896704

>>1896684
radiate as IR from the radiator.

pic related. it's a space radiator.

>> No.1896716

>>1896687
>http://web.mit.edu/newsoffice/2003/cooling.html
Yes. 500 picokelvin achieved.

>> No.1896722

>>1896687
the coolest we managed in lab is 100 picokelvins

>> No.1896731

>>1896687
>>1896716
Helium becomes solid at 1 Kelvin, so its not practical to go much below 3 Kelvin anyways.

>> No.1896769

how well do those radiators work?

with the amount of power needed to run the heat pump, living occupants, and some sort of life support system
how many radiators would you need?

>> No.1896775

guys
RADAR

>> No.1896786

>>1896769
it's high school physics. so why don't you try and do the math? this is /sci/, after all.

>> No.1896797

>>1896775
stealth coating on the heat shield
problem solved

>> No.1896821

>>1896786
i don't know the numbers for the radiators so i can't
every search for space radiator comes up with heaters

>> No.1896833
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1896833

What's going on in this thread?

>> No.1896855
File: 39 KB, 447x335, oh_you.jpg [View same] [iqdb] [saucenao] [google]
1896855

>>1896607
>Diffraction in the vacuum of space
>>1896731
>Helium freezing

>> No.1896874

>>1896775
Angle the "heat shield" somewhat away from the direction you're trying to hide from. Radio waves will bounce off it at an angle, and never make it back to their source. Problem solved.

>> No.1896889
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1896889

>>1896855
>implying diffraction does not work in space
WHAT?

>> No.1896903

>>1896786
>>1896821
>>1896769
∂Q/∂t = Re * (5.67x10e-8) * Ra * Rt4
where
∂Q/∂t = amount of waste heat to get rid of (watts)
5.67x10e-8 = Stefan's Constant
Re = emissivity of radiator (theoretical maximum is 1.0)
Ra = area of radiator (m2)
Rt = temperature of radiator (degrees K)

From project rho (which believes neither in stealth nor has heard of relativistic phase space, but that's another matter.)

>grachaut reflective
WTF Capatacha, you're almost relevant.

>> No.1896904

>>1896821
Depends on the temperature and exposed area of the radiators (to simplify you can simply model them as black-body radiators), and of course the heat flux being pumped out of the shield (which could be quite minimal if the shield is well insulated from the rest of the spacecraft, presuming there isn't another external heat source (i.e. a nearby star).

>> No.1896920

>>1896903
>>1896904
thank you

>> No.1896921

>>1896903
>∂Q/∂t = Re * (5.67x10e-8) * Ra * Rt^4
The last term should be to the fourth power as corrected above. If its a two-sided radiator the effective area is doubled.

>> No.1896950

This entire thread is like watching 6 year olds argue about rocketships...i am FLABBERGHASTED at the retarded.

>> No.1896985

>>1896950
did someone say 6 year olds argue about rocketships?
>>>/k/7435326

btw the op of this thread is from there

>> No.1897046

/sci/ should make more trollscience threads where the troll is actually doing something that is physically possible.

>> No.1897155

bump

>> No.1897303

>>1897046
is this actually possible?
i would think that a crew + life support + some sort of engine + a heat pump would be far too much heat for a radiator assembly to remove
you could make a giant chain of radiators trail behind the ship i suppose, but they would need to be directly behind the ship at all times or they would be spotted
not to mention, they would need to be strong enough to not break off when the ship accelerates

also this is made assuming you know where your target is and that there is only one target or they are in one spot
if they were spread out far enough, wouldn't one of them see the radiators?

>> No.1897314

>>1897303
those are all essentially engineering problems. the actual concept is fairly sound

>> No.1897316

>>1897303
it will work in principle.
all you mentioned are just engineering problems.

>> No.1897321

>>1897316
>>1897314

>engineering mind

>> No.1897329

>>1897314
>>1897316
so assuming we had the technology to create this ship, it would work?

what about the multiple targets thing? would extending the heat shield prevent that?

>> No.1897474

>>1897329
depends on the specific situation. for example, if you approach a planet, chances are that enemies will be hanging out in orbit, and in lagrangean points. knowing that, the size of your heatshield, and your approach vector, you can calculate the point at which you might be detected, and plan your strategy accordingly.

>> No.1897508

active detection (radar, laser detection, etc) would detect it unless it was shaped extremely odd...ANYTHING that big would reflect some portion of signal, no matter how faint.

>> No.1897554

>>1897508
could shape the front plate like some sort of meteor. make it just look like space junk.

>> No.1897558

>>1897508
This.

>>1896855
>Implying no diffraction in space.

>> No.1897568

>>1897554
Or your can just hurl meteors at relativistic speeds from multiple directions. Just sayin'

>> No.1897627

How useful is one-direction stealth?

>> No.1897662

>>1897627
very. f-22 fighter is mostly one-direction (front-bottom) stealth too.

>> No.1897674

>>1897508
make the front a flat plane. unless you're perfectly perpendicular to it, you don't detect anything.

>> No.1897713

If you have a net of satellites orbiting in a solar system [say, at the same distance as jupiter] the best you could do is hide yourself until you pass within this net.

>> No.1897734

>>1897713
If. Also, they're looking outwards, and would concentrate resources there. Once you stop maneuvering you'd have to be looked for even on non-stealthy sides. This allows one to get close, relatively speaking.

>> No.1897750

>>1897734
That's speculative. There's nothing to suggest that future militaries will not have at least a few satellites in the outer reaches of the solar system looking inwards to detect anything that slipped past their sensors looking outwards

>> No.1897756

>>1897750
Do you realize the problems in spotting something against the bright noise of in-system stuff?

Quick, spot Voyager between Earth and Jupiter!

>> No.1897774

>>1897756
You're assuming its difficult to spot things in system. It isn't. Maybe if it was between you and the sun. but not otherwise.

>> No.1898238

>>1897774
It's hard to see distant things that aren't accelerating (engine plume). It's really, really hard.

>> No.1898462

>>1898238
If that were actually true, and not pulled straight out of your ass, we'd have enormous trouble spotting asteroids.

As it is, we're doing easily a hundred thousand new asteroids a year right now, and it's not like these are glowing like lightbulbs in the dark.

>> No.1899129

>>1898462
>we'd have enormous trouble spotting asteroids.
And we do have trouble spotting asteroids, and we detect them with reflected light, not infrared.


>http://www.universetoday.com/62082/newly-discovered-asteroid-will-pass-by-earth-april-8/

>> No.1899139
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1899139

>>1898238
Use cold gas, cooled mass driver, or photon drive for maneuvering and NO DETECTABLE ENGINE PLUME!

>> No.1899174
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1899174

What about a network of ultrasensitive gravitometers? Are the distances too great?

>> No.1899182

>>1899174
Probably impossible unless the hidden ship is extremely massive.

>> No.1901026

>>1899129
>implying your metal spaceship with its large radiators won't reflect a fuckton of light
>reactionface.jpg

>> No.1901094

>>1901026
You need to work on your reading comprehension.

>> No.1901117

>>1901026
don't be retarded. it won't reflect anything from the front aspect, because there's only a perfectly flat plane, big enough to hide all the radiators and other non-stealthy features.

>> No.1901140

>>1901117
>>1901094

Who said anything about front aspect? >>1897750

>> No.1901151

>>1901140
OP.

of course, this type of stealth is unusable in many scenarios. but if you do have it, and enemy does not, you still have an advantage.

>> No.1901158

>>1901151
Indeed OP did. However I was addressing the issue here where front aspect was NOT the problem: >>1897750

>> No.1901160

>>1901140
Make the heat shield bowl or cone shaped then. Radiators have less sky to shine over, but the craft gets even stealthier.

You can go 100% stealthy, for a little while if you put a lid over the radiators themselves. Just don't wait too long and cook yourself.

>> No.1901174

>>1901160
FYI the F-22 Raptor dumps excess heat into is fuel tanks to make itself more stealthy.

>http://www.globalsecurity.org/military/systems/aircraft/f-22-fcas.htm
Scroll down to "Liquid Cooling System"

>> No.1901175

>>1901160
Fair enough. keep in mind since its going to be matte black, it will absorb radiation more readily which means you will have to dedicate more machinery ie more heat into keeping it cooler. and somehwat uniformly cool at that.

>> No.1901235
File: 76 KB, 781x505, AIR_B-2_Close_View_IR_lg.gif [View same] [iqdb] [saucenao] [google]
1901235

>>1901174
>FYI the F-22 Raptor dumps excess heat into is fuel tanks to make itself more stealthy.
looks like someone at Lockheed-Martin didn't get the memo, that IR stealth is completely useless.

pic related, it's "invisible" B2, as imaged by IRST sensor of british air defense system.

>> No.1901254

>>1901235
IR stealth is just supposed to prevent your engines from being glowing beacons for heat-seeking missiles. There's nothing about conventional stealth that is supposed to prevent them from direct IR observation.

>> No.1901283

You don't need a fucking heat shield to be stealthy in space. The distances in space provide stealth enough. It's impossible with any currently practical telescope to detect any kind of practically sized space ship at just the distance of the moon.

>> No.1901293
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1901293

>>1901254
>IR stealth is just supposed to prevent your engines from being glowing beacons for heat-seeking missiles.
sorry, but that's even more unrealistic than front-aspect IR stealth.

>> No.1901306

>>1901283
Sorry bro, but long IR is absorbed the least by the interstellar medium. That's how we are able to see fucktons of h-alpha emissions from all the way across the butt fucking galaxy, save for thick dust and molecular clouds that absorb it.

>> No.1901310

>>1901235
Sercians also downed an F-117 using israeli heat-seeking missiles.

>> No.1901315

>>1901293
wat are you talking about? I was agreeing with you, fucknut.
Stealth doesn't prevent the plane from direct observation through an infrared camera. Just lessens the GLOWING IR BEACON that are the engines for heat seeking missiles.

>> No.1901316

>>1901306
>the intersteller medium
HAHAHAHA. Oh wait, you're serious. Let me laugh harder. HAHAHAHAHA.

>> No.1901331

>>1901316
laugh? You know there is dust and diffuse gas in space right? ie the interstellar medium. http://en.wikipedia.org/wiki/Interstellar_medium
gg laughing at yourself, numbnuts.

>> No.1901334

>>1901315
>Just lessens the GLOWING IR BEACON
not on any meaningful scale. just marketing hype.

>> No.1901345

>>1901315
what he says is that THERE IS NO FUCKING WAY TO COOL DOWN A FLAMING GASES EXAUST AT ANY TEMPERATURE NEAR TO THE SURROUNDING ENVIRONMENT'S unless you dispense a shitload of flares

>> No.1901342

>>1901334
I didn't say it did. I was just regurgitating what I've read. You cannot prevent direct IR observation unless the plane is cooler than ambient if you are trying to be invisible to an observer on the ground looking up.

>> No.1901356

>>1901345
Forget about it, faggot. I was the one going against the space ir stealth bullshit and i was just trying to clarify for you faggots. instead you just turn around and go herp.

>> No.1901364

>>1901310
no. serbians downed F-117 by an ancient soviet radar-guided SA-2 misssile.
it's fire control radar was modded to use lower freqency than usual.
they used it to find out the general area where the plane might be, and sent some missiles there in ballistic mode. one of them got close enough, it's active radar seeker got a return, and BAM.

>> No.1901373

>>1901306
Ever heard of radio/micro waves? IR is readily absorbed by dust grains because of the comparable wavelength and size. Far IR (what is long IR?) is less readily absorbed, yes, but is still prey to low temperature, large molecular dust.

>> No.1901378

>>1901373
long IR -> long wavelength IR

>> No.1901390

>>1901373
Also the point I was making was that its difficult to cool and keep uniformly cool, a plate at the same temp as the ISM. Also, if you happen to transit some bright object behind you, you risk getting detected. Epic route planning and shit

>> No.1901391

>>1901378
>>1901373
Long IR is any wavelength below Infrared. So even radio waves are Long IR.

>> No.1901402

>>1901390
>transit some bright object
Space is big, bro.

>> No.1901407

>>1901391
lol close enough http://en.wikipedia.org/wiki/Long-wave_infrared#CIE_division_scheme

>> No.1901419

>>1901402
so are the nebulae that span the sky, bro. Perhaps if you were coming in from above or below the galactic plane, then you'd be safe from anything bright behind you.

>> No.1901641
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1901641

>>1901419
I actually had to think about this for a while. The answer depends upon the resolving power of the observer.

If the observer doesn't have enough resolving power you will only exist in a fraction of one pixel and your transit will only be noise.

If the observer has enough resolving power that your craft would take up at least most of one pixel, preferably more than one, then potentially they might notice.

BUT this problem gets compounded when you consider that dim, cold objects emit very few photons to begin with and you start to get noise in the image just because photons arrive irregularly. So the effect of transiting another dim object might be less than normal noise from the object itself.

tl;dr: up close, in front of a bright object you are detectable, further away, in front of a dim (but still hot) object you are not detectable.

>Notice how the image is grainy. The image is in focus, but the exposure time was too short. The irregular arrival of photos causes the graininess.

>> No.1901670
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1901670

>>1901641
If you increase the exposure time, you reduce noise in the background and moving objects will be streaked across. There are potentially several problems, one is you have to point your telescope in the same patch of sky for longer, which can suck when you don't know which patch to look in. Also the streak you'd be looking for still might not be detectable, and the longer you expose the image, the longer and dimmer the streak is.

>> No.1901674

>>1901641
yeah, that's true bro.
I'm not familiar with professional grade astronomical imaging equipment, but I can say that they are much more advanced than our consumer cameras (your image looks like it was taken at ISO 1600 on an older camera, or 6400 on a newer one, non DSLRs). they have active cooling for their sensors that does help minimize noise. not enough resolving power i can get behind, but the noise bit... there are image processing techniques (talking out my ass here) that they use to help minimize noise on top of the active cooling for sensor. I am of course not stupid enough to imply that they can add information to an image that isn't already there. good poitn bro

>> No.1901706

>>1901674
I'm mostly talking about noise external to the camera itself. If you're only getting 20photons/second and it deviates between 8 and 32 photons per second regularly, you might not notice a temporary drop in brightness.

>> No.1901715

>>1901674
>there are image processing techniques to minimize noise
Just make sure the noise you're taking out doesn't include the ship you're trying to detect.

>> No.1901720

>>1901715
Indeed. I can't claim to know anything about image processing but I have confidence that any advanced algorithms that scientists run on their images have probably been checked and rechecked to make sure they don't actually add information to the image that isn't already there, hah.

>> No.1901724

>>1901720
I mean aside from accidentally removing useful information

>> No.1901733

>>1901706
Photon noise:
<span class="math">\frac{Signal}{Noise} = \frac{N}{\sqrt{N}} = \sqrt{N}[/spoiler]

Where N is the number of photons detected.

>> No.1901778

Oh god, a 100m diameter object (big enough for you?) at .1ly = 94605284000000m away has an angular size of 6.0563*10^-11 Degrees.

So 2.725 K peaks at 1.9 mm, so to resolve we need our sensors spaced out at 1.9mm / 6.0563*10^-11m =31 372 290 m. Which isn't actually that bad. So if you have multiple telescopes working in tandem you should be able to resolve it.

>> No.1901817

>>1901778
lol... sure if their distance to the object is calibrated to a wavelength of length.

>> No.1901825

>>1901778
FUCKED UP, DID NOT CONVERT TO RADIANS
1.9mm / (1.05702375 × 10^-12 radians) = 1 797 499.82 km

Still its a manageable distance.

>> No.1901831

>>1901817
Wavelength changes resolving power. You need bigger pixels to catch longer wavelengths.