From: chakatfirepaw@gmail.com   
      
   On Sat, 05 Nov 2016 11:09:20 -0700, Mikkel Haaheim wrote:   
      
   > Le mercredi 5 octobre 2016 19:51:29 UTC+2, Rick Pikul/Chakat Firepaw a   
   > écrit :   
   >   
   >   
   >> > It appears that not only have you grossly underestimated the value of   
   >> > H2O for a heat sink, but you have completely failed to take good old   
   >> > insulation into account. Habitation decks can be maintained at a nice   
   >> > 20°C. A central core can be allowed to exceed 100°C. The shell,   
   >> > however,   
   >> > will be maintained at 3°K, with the help of an active He cooling loop   
   >> > (to soak up solar radiation), probably chilled with a reserve of LH.   
   >>   
   >> So more energy generating yet more heat.   
   >   
   > Part of the budget. Yes.   
      
   As I said:  At best, cutting the area you can be spotted from in half   
   will more than double how easy you are to spot in that half.   
      
   >> > Small ones, no. Larger ones, yes. Don't forget about reflected   
   >> > sunlight and solar surface heating. This is what allows WISE to pick   
   >> > out its NEAs.   
   >>   
   >> You mean all the known signals that I can ignore?   
   >   
   > You can't really ignore them, no. Keep in mind that their relative   
   > positions are constantly changing... even the relatively stationary   
   > stars (because of the motion of the platform). In many cases, their   
   > actual orbits are frequently changing, due to the gravitational   
   > influence of large planetary bodies. There is also the fact that their   
   > emission levels are often highly variable, and that they have a nasty   
   > habit of overlapping one another in 2D projection. Also, it has been   
   > discovered that some asteroids can transition into comets, meaning their   
   > mass and orbits are going to begin to vary.   
   > You can't ignore the signals until a LOT of processing work has been   
   > done.   
      
   Processing work that is trivial to do now.  (And no, the difficulty in   
   teasing out the exact sources in a signal cluster hundreds, if not   
   thousands, of light years away are not relevant.)   
      
   You continue to ignore that the sensor platforms don't have to work from   
   a single model of what they should expect to see loaded in once and   
   expected to work for a few decades.  They get to work from having looked   
   at the solar system several times a day.   
      
   >> Insulation doesn't actually help, your heat generation and emission   
   >> will quickly match.  Your heat sinks are based on severe underestimates   
   >> of how much heat you need to deal with and overestimates of how much   
   >> you can absorb.   
   >   
   > The insulation retains the heat o the coolant has time to ansorb it.   
   > Support your claims with numbers.   
      
   That equilibrium has to be reached is basic physics.  As for the numbers,   
   asked and answered in posts you have both responded and reacted to.   
      
   >> >> You assume that the trivial efforts we currently engage in represent   
   >> >> what would be done when watching for hostile military operations.   
   >> >   
   >> > I am taking into account over 2000 years of military precedence.   
   >>   
   >> Except for the stuff I keep pointing out that you are ignoring.   
   >   
   > And what do you think THAT is? I do not recall you mentioning anything   
   > specific.   
      
   If you want someone to dig through posts from months ago, you are going   
   to have to do it yourself.  Eternal September's retention is only about   
   two months.   
      
   >> > The observation capabilities of WISE and Hubble are FAR more advanced   
   >> > than anything the military has to offer.   
   >>   
   >> Um, I take it you missed the news from a few years ago when the NRO   
   >> transferred two of its satellites to NASA.  NASA themselves has said   
   >> that the optics are better than Hubble's.   
   >   
   > You do realise that the NRO is only rather lossely affiliated with the   
   > military (it answers to the secretary of defense, and military personnel   
   > are sometimes assigned to projects)?   
      
   Careful with that line of argument, as the kind of work the NRO does   
   would include the exact kinds of stations we're talking about here.   
      
   > You realise also that it relies heavily on civilian contract?   
      
   As do most western militaries.   
      
   > part of its budget does come from military   
   > funds, but part also comes from intelligence agency funds.   
   > I would be interesting in reading the report. However, keep in mind that   
   > the Hubble was built for a very different mission than recon sats.   
      
   So you concede that the reason that the scientific gear is better at look   
   for space targets is because it was built for it.   
      
   (JSYK:  This is what is known as an 'own goal'.)   
      
   >> > Not exactly, although this remains an option. No. Although it is not   
   >> > possible to prevent some emission leakage, in all directions, it is   
   >> > possible to manage how much is leaking in which directions through   
   >> > careful architecture, orientation, and angling.   
   >>   
   >> If you don't actively cool, they will heat up and become emissions   
   >> sources, (well, more of an emissions source).   
   >   
   > I am not saying they don't become emission sources. I am saying you can   
   > control, somewhat, where the bulk of those emissions goes.   
      
   To get that control, you have to cool the surfaces pointing in other   
   directions.   
      
   >> > True. You need more radiator area. That means a risk of detection.   
   >> > However, ships have been engaging in stealth behaviour through   
   >> > managing the aspect area they present for hundreds, if not thousands,   
   >> > of years. That is what is required, here.   
   >>   
   >> They have been doing it in a different environment.  Remember, on Earth   
   >> you get to hide from most potential observers by putting a planet   
   >> between you and them.  That isn't so easy in space.   
   >   
   > Only in the past few hundred years.   
      
   Nope, always.  Just what you you think being "over the horizon" means?   
   Or, for that matter, being on the other side of a hill?   
      
   > Yes, space is a different environment. The scales of distance have   
   > increased vigourously over the past couple centuries. However, many of   
   > the techniques used are still valid, although they must continously be   
   > refined.   
      
   Most of those techniques rely on physical obstruction and nigh-limitless   
   cooling fluids.   
      
   >> > However, you are ignoring the factor of heat sinks and insulation.   
   >> > Yes, eventually, you are gong to have to dump the heat, but you can   
   >> > control when and how... and put it to a good advantage, such as   
   >> > additional manoeuvering thrust.   
   >>   
   >> Thrust = being detected.   
   >   
   > Not necessarily. Depends on the temperature and mass of the exhaust   
   > producing the thrust.   
      
   Low temperatures means low specific impulse.   
      
   Low Isp means either large mass expenditures or little thrust.  There is   
   a reason why cold gas thrusters are generally restricted to being used   
   for attitude control.   
      
      
   [continued in next message]   
      
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