Loading ...
Sorry, an error occurred while loading the content.

Something completely different (there is hope for space after all)

Expand Messages
  • Keith Henson
    This is something that has not been covered by news nor (as near as I can tell) has it been the subject of a press release. But it is fairly well known to
    Message 1 of 2 , Jul 12, 2011
    • 0 Attachment
      This is something that has not been covered by news nor (as near as I
      can tell) has it been the subject of a press release. But it is
      fairly well known to those in the business.

      NASA Ames brought a 1.2 MW, 110 GHz gyrotron for testing beamed energy
      propulsion. They still need the power supply, which is 70 kV at 30 A
      but it's a relatively small cost compared to the gyrotron. Up close
      it will provide well over 10 MW/m^2.to test hydrogen heaters.

      They intend to offer the use o it the same way as the wind tunnels, as
      a national engineering test asset.

      I think it is an accepted truth that you need single stage to orbit
      and that it must be a reusable launch vehicle to get the cost to GEO
      down to where power satellites make sense economically.

      Given the current state of material science and the best exhaust
      velocity you can get from chemical propulsion, neither of these are
      feasible.

      To put numbers on the problem, it takes 9000 m/s to get into LEO. For
      4500 m/s rocket engines, that's a delta V of twice the exhaust
      velocity. The rocket equation gives a mass ration of 7.4 which means
      the vehicle and payload can't be more than 13.5% of the takeoff mass.
      For a vehicle to be reusable, the accepted minimum structure is 15%,
      leaving less than zero for payload. (Skylon cheats by burning air
      partway up, but it's not enough to get a lot of payload to LEO.)

      But if you have 9000 m/s exhaust velocity, which can be done with
      hydrogen heated with microwaves or lasers, then the mass ratio is a
      little less than 3. So vehicle and payload can be 36% of takeoff
      mass. If half vehicle and half payload, that's 18% each. So a 300
      ton vehicle with a dry mass of 54 tons could put 54 tons in LEO.

      The falling cost of microwave power and laser power makes these
      options possible.

      Beamed energy propulsion doesn't make economic sense unless you are
      moving cargo volumes in the hundreds of thousands of tons per year--
      which happens to be the right size for a serious power satellite
      project.

      I should also add that I never thought NASA would do something so
      sensible. Those of you who know Pete Warden might send him a thank
      you note..

      Keith

      PS https://www.fbo.gov/index?s=opportunity&mode=form&id=6ee365a77d240df7a668f5746cf71665&tab=core&_cview=1

      _______________________________________________
      http://box535.bluehost.com/mailman/listinfo/brin-l_mccmedia.com
    • Alex Gogan
      Ok sent out a few invites and have a few more left, what you need if you want one is a google account which you can get free from www.gmail.com Email me back
      Message 2 of 2 , Jul 19, 2011
      • 0 Attachment
        Ok sent out a few invites and have a few more left, what you need if you
        want one is a google account which you can get free from www.gmail.com

        Email me back here and can then set up a nice channel on google+ which
        is brilliant.

        Regards

        Alex

        _______________________________________________
        http://box535.bluehost.com/mailman/listinfo/brin-l_mccmedia.com
      Your message has been successfully submitted and would be delivered to recipients shortly.