From: mikkelhaaheim@gmail.com   
      
   Le lundi 26 septembre 2016 01:19:13 UTC+2, Rick Pikul/Chakat Firepaw a   
   écrit :   
      
   Okay, getting back to you...   
      
   > > Still, I   
   > > have demonstrated that the mass can be significantly reduced for more   
   > > reasonable strikes. You can even decrease the mass below 1g, especially   
   > > if you decide to use an explosive shell or armour piercing design.   
   >    
   > Um, no.  First of all, at the speeds we are talking non-nuclear warheads    
   > are nothing but a sub-munition distribution technique due to the 1st law    
   > of space combat, (at 3 km/s you pack your own mass in blam).     
      
   I also wanted to say on this first point that you are actually making the job   
   easier for me. The fact that just a little mass has so much destructive energy   
   supports my statement that the total mass required can continue to be reduced.   
      
   Furthermore, although you are quite correct about armour peircing shells not   
   being a requirement, I had a slightly different intent in mind for the use of   
   the explosive shell, which I should have made more explicite. Detonating the   
   shell just before    
   contact sends a splatter of shrapnel, which is quite effective at scouring   
   detectors, rendering them unusable. This also takes care of those gap issues   
   we were discussing.   
      
   Second, you    
   > have to drop the mass/area by multiple orders of magnitude, (using my    
   > earlier, wrong, calculation:  To get to 'only' a kilotonne of stuff you    
   > need to get down to 10 _micrograms_ per square metre).   
      
   Or decrease the target area. Yes.   
      
   >    
   > > In war, "sane" amounts of material is quite subjective.   
   >    
   > Masses measured in Zg are almost never sane.   
      
   Depends upon the amount of waste material being excavated with the usable   
   material. Also depends upon the energy available. If we are dealing with   
   colonies that can afford building their own space navies, the availablity of   
   both will likely be extremely    
   high.   
      
   >    
   > Except that you aren't launching 100 of them, you are launching trillions    
   > of them.   
      
   Probably. But this is a benchmark from existing tech. Using existing tech, it   
   gives you an idea of how much energy will be required (yes, it is phenomenal,   
   but militaries are often ready to use "phenomenal" resources in times of war.   
      
   >   
   > Um, that figure I used was for launching from Ceres, (it's actually ~7.5    
   > km/s, but I was only claiming an order of magnitude).  To get down to ~3    
   > km/s you need to be out past Saturn.   
      
   Sorry, I did not have the data for Ceres at the time. I was using a guestimate   
   from inside of Jupiter's orbit. I believe your figure from Saturn includes   
   escape velocity requirements. From a shared orbit with Jupiter, but NOT in its   
   SOI, the figure I get    
   from a number of different sources confirms a required Delta-V of about 2.5   
   km/s (rounding up to 3 km/s gave me that guestimate value from somewhere   
   inside Jupiter's orbit.   
      
      
   >    
   > All of which are in line to hit your launching facility.  Further, you    
   > have already defined them as something that can damage space hardware as    
   > opposed to the tiny dust of a comet's tail.   
      
   First, you are assuming that these are failing to achieve escape velocity.   
   Once again, providing them with sufficient delta-V to escape the solar system   
   is not difficult.   
   Second, the orbits are going to be out of phase. Yes, if they fail to leave   
   solar orbit, they might return to where they were launched from... but it will   
   likely be thousands of years before the disperse orbits are in-synch again.   
      
   > > If you scan, yes. However, if you scan, you leave open large windows   
   > > where you can sneak manoeuvres in.   
   >    
   > Not as large as you think.  Low end you will be looked at every couple of    
   > minutes, high end you are in an 'extra scanning' zone and it's measured    
   > in seconds.   
   >    
      
   Do you have any documentation to support this assertion? Higher scan speeds   
   come at the cost of sensitivity. WISE/NEOWISE is currently the most sensitive   
   IR platform deployed (to the best of my knowledge). It has been able to detect   
   objects as small as 1    
   m (at relatively close range), or as dim as 50W to 100W (absolute). However,   
   it requires 6 months to complete a single full-sky scan, and has not come   
   close to detecting everything.   
      
   >    
   > Closed life support systems currently need ~7 kW/person, we're talking    
   > about interplanetary trips here so we can't go to an open system, (that    
   > can get down to ~300 W/person).  Let's be generous and say 1 kW/person,    
   > let's also be generous and say the power plant is 40% efficient so we are    
   > generating 2.5 kW/person to deal with.   
      
   Do you have a link to the source info for this? I would be very interested in   
   looking it over.   
   There is really no reason why you can't have open LSS for small crews. I have   
   calculated from various sources that 10 tonnes per person is more than   
   sufficient to cover all the LSS needs for a 1000 day mission, without   
   recyclation (scrubbing and    
   filtering would still be required, however. Alternatively, the same 10 tonnes   
   would be more than enough for 3 people for just under a year. Keep in mind   
   that about half of this will be stored in the form of H2O from the heat sink   
   supply, and cryogenic O2    
   (also useful as a heat sink). Note: this also accounts for a few tonnes worth   
   of personal belongings or personal work items.   
   I also have gone through the numbers, and have found that 10 tonnes of H20 is   
   sufficient to absorb well over 100 kW of continuous waste heat over a mission   
   duration of 400 days (or 400 kW over 100 days, if you prefer). For comparison,   
   100 kW is the    
   nominal maximum power draw from all the systems on board the ISS. Note,   
   however, that we are only concerned here with waste heat. Energy going into   
   work is undetectable, unless that work is to generate heat or other radiative   
   emissions.   
      
   >    
   > That means your ice heat sink only deals with just over three man-days    
   > per tonne.  That's just for life support, no electronics, (there's    
   > another couple kW), no drives, no reaction wheels, (i.e. no rotating to    
   > keep your cold side the way you want), no heat pumps, (you know, so that    
   > your heat sink actually works), no solar radiation absorption, (that's    
   > going to be something like 10+kW alone), etc.   
      
      
   [continued in next message]   
      
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