From: mikkelhaaheim@gmail.com   
      
   Le samedi 18 juin 2016 03:48:51 UTC+2, eripe a écrit :   
      
   >    
   > For 99% of the sky, thats fine. If you get a blib, you can dedicate more   
   sensor resourses to that area.    
      
   Two problems with this: First, you need qualitatively different sensor   
   packages for the task; second, the dedicated resources either mean less   
   coverage or greater costs.   
   There is a limit to how much resultion can be achieved. The formula for   
   telescopic resolution is R=wavelength/baseline. At 1AU, a capital ship of 362m   
   in length would cover 0.001 arcseconds. This is the resolution limit for   
   visible light, using a 200m    
   telescope. This means that the Arecibo Observatory (305 m) would detect the   
   visible light from this capital ship as a single dot (you might be able to see   
   two capital ships, if they are at least a a hundred meters apart from one   
   another). If you want to    
   acquire an IR signature of the same vessel, again as a single dot, you will   
   need an 800 KILOmeter telescope array. If you want 1m resolution, which is   
   still not good enough for the kind of analysis that AR was suggesting, you   
   will need a single telescope    
   array baseline AT LEAST 100 000 km long. This would, again, not be good enough   
   to analyse the exhaust plume. But, yes, this will at least give you a fairly   
   good position, for as long as you have a signal.   
   Next, you have to consider the cost of this array. You still need a second   
   array in order to get the 3D info... but again, this is not good enough for   
   the kind of analyses AR was suggesting.    
   In any case, your suggestion ignores the simple bulk of military traffic,   
   involving vessels of all sizes. You put an array to the task of tracking one   
   blip, you leave open quite a lot of space for all the others to pass through.   
      
      
   >    
   > > So, two problems here: low res, and very small likelihood that two   
   observation posts will actually be scanning the same patch of space at the   
   right time. This latter becomes even more difficult because in a future with   
   high volume space traffic,    
   scans from any single detector are going to identify potentially hundreds of   
   targets, which means you have to try to match the targets from the two   
   observation posts. This is even more difficult if you have dense traffic   
   patterns.   
   >    
   > But not impossible. All legal vessels will be carrying transponders allowing   
   you to match them up with the blibs. If you get a blib without a transponder   
   you can put a kee   
      
   In peace time, sure. In war time, all transponder traffic will go dark. For   
   that matter, you are making some assumptions about the laws that will be in   
   place, and about how many people will actually be following those laws. Then   
   you have to consider the    
   volume of legitimate military traffic that is not always going to want to   
   advertise its presence.   
      
      
   >    
   > > Another consideration is the amount of money you are talking about, and   
   the strategic/political environment. For the former, you might think that 100   
   time the cost of a small observation satellite is negligible... until you   
   consider that you have to    
   deploy that platform in space. In order to reduce the scan time by a factor of   
   100, you need to increase the volume (and mass) of equipment by a factor of   
   100. Interplanetary probe space flights cost tens of MILLIONS of dollars (or   
   much more... the    
   current count for the two voyager probes is reported at over $800 million, in   
   1970s currency). Multiply this by a hundred times,   
   >    
   > Each ship in your own fleet will cary such a sensor package.    
      
   Sure. All ships will be equipped with sensor packages. But the resolution of   
   those sensor packages will be quite limited. At best, they will carry sensors   
   with a 10m baseline (this is being generous: most of those sensors will be   
   hard pressed to put in a    
   1 m baseline). This will give you a resolution of 13 000 km^2 per pixel.   
   Of course, future tech will allow you to link all your vessels together so   
   that your fleet can provide you with a collective array baseline on the order   
   of perhaps 1 000 000 km. However, it will take a long time for the sensor data   
   from all these vessels    
   and craft to be processed... and you need to maintain active communication.   
   Also, the sensor arrays will take away from the other capabilities of the   
   vessel. Every g of sensor array is a g that has to be subtracted from   
   somewhere else. There is absolutely zero possibility that ANY ship will be   
   able to provide full field of view    
   coverage with any kind of resolution, let alone every ship.    
      
   I made a small miscalculation earlier. I assumed that small observation   
   platforms would be suffiient to provide the resolution if there were a   
   sufficient number of platforms. Sorry, no. I followed up with the research,   
   and that is when I found that there    
   is a physical limit (not a tech limit) on the relationship between resolution   
   and baseline. Even your 100 °^2 scanning array s going to be huge if you want   
   both the sensitivity and the resolution to even sort out one capital ship from   
   another.   
      
      
      
      
   >    
   >  then multiply that by a few thousand times to get reasonable 3D coverage,   
   >    
   > I think 3-4 would do.   
      
   Perhaps. This depends a bit. If you have arrays of large (sensative)   
   telescopes with a baseline of 1 000 000 km, and full field of view; then, yes,   
   3 or 4 such arrays will give you reasonable 3D coverage... except, for some   
   blind spots very near    
   obstructions (the more sensor arrays you have, the fewer and smaller those   
   blindspots). However, each base telescope is going to have to be at least 35 m   
   in order to have the necessary sensativity. Four such telescopes 1 000 000 km   
   apart can give you the    
   baseline, for all axes. Assuming a 100 °^2 window for each telescope, 480   
   telescopes (not 100, because that would mean you still have to scan) arranged   
   in a sphere at each point in the tetrahedon should give you the full field of   
   view without need for    
   scanning. Stand each of these arrays a billion km or so from one another, then   
   yes, 3 or 4 arrays should be sufficient.   
   The problem with this is that we're assuming that the arrays can be placed in   
   stable tetrahedron formations. Not likely given gravitational dynamics. You   
   will want more platforms in order tomake up for irregularities in positioning.   
   However, you would be    
   correct that you don't need 1000 x the number of platforms. Rather, it is the   
   cost of all the supporting equipment that will bring that number up to 1000 x.   
      
      
      
   >    
      
   [continued in next message]   
      
   --- SoupGate-Win32 v1.05   
    * Origin: you cannot sedate... all the things you hate (1:229/2)