From: nuny@bid.nes   
      
   On Saturday, July 23, 2016 at 12:33:13 PM UTC-7, Mikkel Haaheim wrote:   
   > Le vendredi 22 juillet 2016 20:19:09 UTC+2, Sea Wasp (Ryk E. Spoor) a   
   écrit :   
   >    
   > > 	Space doesn't have anything to HIDE you. Earth does.    
   >    
   > Air doesn't have anything to hide you (if you are using IR, anyway).    
      
     I've been lurking this thread, and have noticed lots of unstated assumptions   
   by all participants.   
      
     It might help to state exactly what we're trying to stealth, what we're   
   trying to stealth it *from*, and then we can start talking about the   
   characteristics of the environment that might help or hinder our stealthing   
   efforts *for that particular case*.   
      
     Emphases because hiding a battleship from a mosquito is not the same task as   
   hiding a mosquito from a battleship, or hiding one mosquito from another or   
   one battleship from another.   
      
     Both have different profiles *in the sensorium of the other* which is the   
   critical point. Yes, the mosquito is limited to the sensorium it evolved with   
   and the battleship can retrofit whatever humans can think up, but not   
   generally while trying to hide    
   *or* seek.   
      
     Environmental variable obviously affect chance of detection too but you have   
   to start somewhere.   
      
   > >You can't see through clouds like Superman's X-Ray vision    
   >    
   > You can with IR.   
      
     Yes, if it's available, and if there isn't a chemical fog in the way that   
   absorbs or diffuses IR beyond reliability or emits masking IR of its own.   
   Producing such "smokescreens" in space is far more difficult than in   
   atmosphere but certainly not    
   necessarily impossible or infeasible on the inherently massive economic scale   
   of interplanetary or interstellar warfare.   
      
   > >  and scan the bottom of the sea .    
   >    
   > You have a point there. OTOH, stealth only works underwater because nations   
   > still WANT it to work underwater. Sonar is extremely effective in water...   
   > but it gives your position away.   
      
     Active sonar does, yes. Passive sonar doesn't which is a better analog of   
   the typical systems suggested for space warfare detection.   
      
   > This is not a problem, however, if the sound generators are deployed   
   > throughout the oceans en mass... but EVERYONE will be able to hear the   
   > reflections. Nothing in the oceans would ever by stealthy again.   
      
     Until the easily-located "illuminators" are destroyed, which will be a   
   priority for all sides.   
      
     Passive sonar imaging on small scales (arrays a few meters square, range a   
   few dozen meters, resolution a few centimeters) has been demonstrated in the   
   public domain. The "illumination" is ambient ocean noise.   
      
     I have absolutely no doubt that all major military maritime players have   
   already deployed large networked passive arrays that can track pretty much any   
   object that might be a threat anywhere in Earth's oceans, if all were linked   
   together (eliminating    
   hiding behind seamounts, thermal layers, etc.). The hoary old SF cliche of   
   aliens having submarine bases is just flat-out impossible now, barring   
   collusion from the humans in charge of the part monitoring the alien base's   
   location.   
      
     Using that information is a different matter in submarine warfare- the   
   collated, analyzed data has to be securely accessible by the subs. You can't   
   use comms lasers as you can with spacecraft.   
      
     Notice that if we used submarines for shipping rather than surface ships,   
   the commercial carriers would have had to develop this capacity if only for   
   traffic control.   
      
     In space it's actually easier unless warships don't have to limit themselves   
   to things like Hohmann trajectories, but that's way beyond the "current tech"   
   goalpost that keeps being referred to.   
      
     If they do, the volume of space that must be kept under constant *detailed*   
   surveillance for planetary defense becomes much smaller. The same applies to   
   intership engagements within the Hill spheres of astronomical bodies.   
      
   > >  You can't track every plane all the time --    
   >    
   > Sure you can, if you deploy the kind of tracking network we are talking about   
   > for space use. We don't... but this is not because of tech limits, but other   
   > constraints that will also affect space-based sensor platforms. Also, keep in   
   > mind, the future where we will be placing military vessels in space to   
   > protect space assets will also be the future where space traffic is common   
   > place... as common as air traffic.   
      
     Our current air-tracking network coverage is driven mostly by commercial   
   limits; we install only the minimum required to keep the risks of losing track   
   of a plane to an insurance-acceptable minimum. Military expenditures for   
   similar tasks tend to be    
   more lavish because more is at stake.   
      
   > > we have devices that sorta give us tracking but we don't and can't track   
   > > them along their entire paths accurately (or we'd never lose a plane).   
   >    
   > There is no tech limit preventing us from doing so. The reasons preventing us   
   > from tracking every plane are EXACTLY the reasons that cause the "there ain't   
   > no stealth in space" argument to fail. That is, it's expensive and we don't   
   > consider it a worthwhile investment.   
      
     Losing an airliner or two per year is a few-dozen-millions-of-dollars risk   
   airline insurers accept.   
      
     Losing a *planet* even once is not an equally-acceptable risk, so space   
   warfare sensor capabilities will necessarily be much more elaborate than   
   anything so far discussed.   
      
   > > 	This is actually one of the key points I make in the Arenaverse novels.    
   > > Fighting in Arenaspace is NOTHING like fighting in our home space,    
   > > because the Arenaverse is filled with atmosphere (and other stuff) that    
   > > makes it quite possible for you to pull off "stealth" tricks and end up    
   > > with engagement ranges back in the "humanly comprehensible" distance range.   
   >    
   > Atmosphere does not permit stealth. Actually, atmosphere makes stealth much   
   > harder, because now you have to deal with sound and airborne chemical   
   > diffusion.   
      
     Do not assume perfect seeing at all times, even in IR. It can even work   
   against you if you do have it; attacking out of the Sun is an old WWI trick   
   still used by today's fighter/bombers.   
      
   > > 	Space is, for the most part, empty. It's got some number of dust    
   > > particles and molecules per cubic meter but it is effectively completely    
   > > empty for most purposes. It won't attenuate your signals or absorb them    
   > > or allow you to refract them.   
   >    
   > Which is exactly why you have so much trouble with background sources (CBR,   
      
   [continued in next message]   
      
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