More nuclear propulsion...

[JPreisig@AOL.COM]

Hmmmmm,


      This is from:   jpreisig@aol.com    .


      Howdy Radsafe people...  Hope all is well in your neck of the woods.

      So, I guess we (the USA) are down to 3 (???) space shuttles.

      I guess it is time to build 3 to 5 new space shuttles, or whatever

      spacecraft NASA is proposing to build next.  I suppose we (the USA) can

      build these spacecraft over the next 5 or 10 years.  Let's use existing

      technology to improve the next set of spacecraft.  Existing shuttles are

      10 to 20 years old???  How many flights should a shuttle make, before it

      is retired from the fleet???


      Dr. Cohen is pretty correct.  Nuclear propelled spacecraft need never get

      close to Earth again, after they are launched the first time.  We could have

      spacecraft that bring materials up to the space station (or the moon???)

      and then have nuclear-powered spacecraft that go out into space

      from the space-station or moon.  Maybe someday we'll even do nuclear

      refueling at the space station.


            I'd prefer a nuclear propelled spacecraft based on fusion, but fission

      propelled spacecraft may have to do for now.  The US fusion community

      has just jumped back into the ITER fusion program, funding-wise, with 

      a schedule lasting another 10-15 years.  I may be quite old before we see

      any commercial fusion energy.  The US is also continuing to fund

      existing fusion programs (NSTX at Princeton's Plasma Lab, etc. ---

      see their web-site).


           I guess some of my crude calculations (described on radsafe) 

      resulted in nuclear propulsion-based one-way trip times to Mars of about

      one or two weeks.  So, in a total time of one month (trip to Mars), how 

      much Cesium, Strontium (fission fragments, etc.) does one create by

      fissioning U-235 or Plutonium???  Not very much, I'll bet.  So much for

      any big hazard, if one doesn't run the reactor all that often, and if one

      refuels periodically.


           One big aspect of nuclear propulsion that is being somewhat ignored,

      is that nuclear propulsion gives one available energy (and power) to

      give improved (and more-controlled) flight (dynamics) performance.

      A spacecraft (with nuclear propulsion) re-entering the Earth atmosphere

      and experiencing difficulties might (with some warning) be able to go back

      into space, and perhaps wait for a rescue shuttle.


           Clearly, one might not get 1000 times more energy from nuclear

      propulsion (over chemical systems) but a factor of 5 to 100 might be nice.

      Maybe that is too much available energy, but nuclear propulsion

      systems will have energy (inefficiency) losses also.  I am very sorry to

      to hear of the recent lost shuttle.


           In other news, Brookhaven National Laboratory has a new director ---

     see their web-site for details.  A chemist (Ray Davis), formerly at

     Brookhaven, won the Nobel Prize (in Physics --- with several other people)

     for his work in cosmic ray research.  The people at RHIC (the Relativistic

     Heavy Ion Collider at Brookhaven) are now colliding deuterons with Gold.

     There is a link on BNL's Main Web-page to see how AGS/RHIC is

     running.  Some of the experiments at RHIC are PHENIX, STAR, BRAHMS,

     PHOBOS, etc.  The BNL web-pages have links to the web-sites of 

     these experiments.  Browse at will???


           Have a good weekend....


                               Regards,             J.R. Preisig,   Ph.D.