XPost: soc.men, talk.environment, sci.environment   
   From: rally2xs@att.net   
      
   On Sat, 27 Jan 2007 22:41:03 -0800, The Ghost In The Machine   
    wrote:   
      
   >In sci.environment, Dave Head   
   >   
   > wrote   
   >on Sun, 28 Jan 2007 05:33:04 GMT   
   ><17dor2hv34a2h408jmm8v6g46brjno4la3@4ax.com>:   
   >> On Sat, 27 Jan 2007 12:12:57 -0800, The Ghost In The Machine   
   >>  wrote:   
   >>   
   >>>In sci.environment, amused onlooker   
   >>>   
   >>> wrote   
   >>>on Sat, 27 Jan 2007 16:19:11 GMT   
   >>><3YKuh.81948$HV6.22835@newsfe1-gui.ntli.net>:   
   >>>> "Dave Head"  wrote   
   >>>>   
   >>>>> On Fri, 26 Jan 2007 12:54:15 GMT, "amused onlooker"    
   wrote:   
   >>>>>   
   >>>>>>"Dave Head"  wrote   
   >>>>>>   
   >>>>>>   
   >>>>>>   
   >>>>>>>  because we don't have the capability to   
   >>>>>>> do anything radical enough to prevent it anyway   
   >>>>>>   
   >>>>>>Actually we do.   
   >>>>>   
   >>>>> Actually, we don't.  There's no way in hell to get the CO2 down to a   
   >>>>> sufficiently low level to keep what's about to happen from happening   
   >>>>> without screwing up millions of lives, which includes a lot of deaths   
   >>>>> from lack of the resources that would otherwise be produced by the   
   >>>>> activities that now produce the CO2 but would have to be eliminated -   
   >>>>> power generation, transportation, etc.   
   >>>>   
   >>>> The "short term" solution I was thinking of was a solar screen to   
   >>>> control/cool the earths temperature. Not ideal I realise but it would buy   
   us   
   >>>> some time to develop alternative energy sources and maybe find a way of   
   >>>> cleansing the atmosphere.   
   >>>   
   >>>Let's crunch.  The general GW imbalance AIUI is about 1 W/m^2, averaged   
   >>>worldwide.  The world's surface area facing Sol is 2.5559 * 10^14 m^2.   
   >>>The insolation averaged daily is about 600 W/m^2.  In order to   
   >>>adjust this imbalance one needs a space mirror whose total area is   
   >>>2.5559 * 10^14 / 600 m^2 = 4.25988 & 10^11 m^2.  If one assumes aluminum   
   >>>foil thickness of 0.02 mm, one gets 8.51976 * 10^6 m^3 or 2.3 million   
   >>>metric tonnes of aluminum.  At a launch cost of about $1000/kg that   
   >>>works out to 2.3 trillion US dollars.   
   >>   
   >> If we could produce aluminum on the moon, and send it toward L1 with a   
   railgun,   
   >> I think the cost might be much less for both production and launch.  This   
   may   
   >> be doable in 20 - 40 years with sufficiently advanced artificial   
   intelligence   
   >> and other robotic advances.   
   >   
   >Plus the ability to refine aluminum from lunar rock.   
   >I'll admit I have no idea how that might be accomplished,   
   >though if it's anything like bauxite on Earth there'd   
   >probably be electric current involved. :-)   
      
   Well, the beauty of the whole thing is that the technique is applicable far   
   into the future.  While a strategy to reduce CO2 to combat global warming may   
   indeed have a time limit, this has a much longer one.  It can be applied at any   
   time and will begin lowering temperatures just as soon as its construction is   
   commenced.   
      
   >> The power source for doing this, direct sunlight,   
   >> packs more energy when striking the moon than when filtered by the earth's   
   >> atmosphere,   
   >   
   >Not as much as one might think; the ratio is about 1.3 to   
   >1, though I'd have to look to be entirely sure.   
      
   Yes, 30% or so gets lost in the atmosphere.   
      
   >No miracles here, though it helps a little bit.   
   >   
   >> so, providing solar energy recovery advances sufficiently in terms   
   >> of $ / watt, it would seem that basing such a thing on the moon might be   
   >> doable.   
   >   
   >The question might be which is cheaper.  The Moon, after   
   >all, has overhead to contend with -- someone has to boost   
   >from Earth to moon and set all this up.   
      
   Setting up the necessary manufacturing on the moon, and then boosting from   
   there at 1/6th the gravity influence would seem to be much better than boosting   
   everything from earth.   
      
   >>>Looks vaguely doable but very pricey.  (These factors of   
   >>>course are very rough estimates; Google in particular suggests the   
   >>>imbalance can be from 0.1 to 0.6 W/m^2.  This may mean I'm   
   >>>overestimating by a factor of 2 to 10.  Of course, counterbalancing that   
   >>>is the launch costs, which are highly variable depending on vehicle used   
   >>>and destination.)   
   >>   
   >> And where its launched _from_...   
   >   
   >True, if the moon is a possibility that might simplify things.   
      
   Yep.   
      
   >>>There is the further complication of what we put into the atmosphere as   
   >>>the result of a launch.   
   >>   
   >> ...and here's hoping for a largely electrical launch eventually, especially   
   >> enviro-friendly if it were to be done by space elevator. (Someone is   
   _going_ to   
   >> get that working in the next 50 years or so, I'd bet...)   
   >   
   >There are a fair number of technical problems, mostly   
   >because of erosion of the elevator superstructure by   
   >orbiting charged particles.  (There are also issues if one   
   >of the countries decides to play target practice again.)   
      
   It would seem that ascending repair parts to deal with the erosion would also   
   be much easier on the teather than boosting via rocketry.  As for people   
   playing target practice, those people will just have to get their asses kicked.   
      
   Dave Head   
      
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