From: mikkelhaaheim@gmail.com   
      
   Le mercredi 15 juin 2016 15:31:28 UTC+2, eripe a écrit :   
   > > >    
   > > > To go anywhere you will need to turn your drive on, and then people will   
   know your trajectory, and they will be able to calculate it very precisely, so   
   even if they can’t see you, they will still know where you are.    
   > >    
   > > This is not so easy as the AR crew would have us believe. All observation   
   is essentially 2D. In order to determine the trajectory, you need 3D   
   information. For example, is that 2km gas cloud travelling laterally to your   
   location? is it at an angle (   
   which means it is considerably longer than 2km)? Is it the entire cloud, or is   
   part of it being obscurred?   
   > > Next, the detectors that can extract such precision data are extremely   
   narrow field. You need to now exactly where the target is in order to use it.   
   Burnsides 4 hour scan can only provide resolution of 1225 km^2/pixel at 1   
   AU... and that is assuming    
   you actually know the distance. At such low resolution, at such intervals of   
   detection, it will not be possible to maintain a position lock long enough to   
   bring the precision equipment into play.   
   > >    
   > >    
   >    
   > For this one, a few other detectors in say, Earth-Sun Lagrange points, would   
   let you triangulate.   
   > Considdering how important it would be to have the intel of where all   
   dangerous vessels are, im sure we can do better than a 4 hour scan time. Just   
   spend 100 times the money, and your down to 144 seconds. (Im assuming the is   
   still small compared to the    
   cost of any spacecraft, and peanuts compared to a surprise visit from an angry   
   torchship)    
      
   The triangulation will only work if two different observation posts happen to   
   be scanning the same zone at the same time, and happen to detect a   
   simultaneous reading. Even then, resolution is a big problem, because the four   
   hour scan, even if you reduce    
   the scan time through redundant observation posts, will not permit accurate   
   size measurements. You only know that there is something within about a 40 000   
   km^3 swath... assuming that the distance from each observation post is less   
   than 1 AU.   
   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.   
   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, then multiply that by a few   
   thousand times to get reasonable 3D coverage, then multiply THAT by at least a   
   several thousand    
   times to get useful resolution. Then factor in the strategic/political   
   environment. In a time of war, you can either use the money to buld   
   observation platforms, or you can use it to build warships. As useful as   
   observation is, wartime is too late. The    
   military is going to want to maximise offensive and defensive capability. In a   
   time of peace, you have to convince the population that there is a credible   
   threat that will warrant such costs, and lots of the public are going to be   
   rather nervous about    
   having all those spies deployed. The public simply won't condone such an   
   expense to spy on forces that are not even a threat (yet), especially if they   
   consider that the enemy might some day be themselves.   
   In our age, nuclear power is reserved for warships. But in days of   
   interplanetary travel, nuclear power will be a requirement for virtually all   
   commerce and enterprise. ALL interplanetary vessels will have at least fission   
   power. Many colonies will have    
   civil fusion reactors, if anyone actually gets them to work. Some level of   
   fusion drive will be available to anyone who has the resources.   
      
   --- SoupGate-Win32 v1.05   
    * Origin: you cannot sedate... all the things you hate (1:229/2)