From: niklas.holsti@tidorum.invalid   
      
   On 2020-11-05 14:36, Alain Fournier wrote:   
   > On Nov/5/2020 at 02:22, JF Mezei wrote :   
   >> On 2020-11-03 18:47, David Spain wrote:   
   >>> Will NASA use it?   
   >>>   
   >>> No. But a private company might.   
   >>   
   >> If you're carrying humans (or Martians, apparently they have bee voting   
   >> illegally in USA :-), I have to assume that shielding requirements will   
   >> be very hefty. Does all that extra mass make this type of propulsion   
   >> worthwile?   
   >   
   > You just put the reactor far from the crew and put a little shielding   
   > near the reactor. You also have to put shielding around the crew, which   
   > you would have to do even if your propulsion method was chemical. There   
   > are all kinds of radiations in space, you need shielding.   
   >   
   >> And out of curiosity, how does nuclear propulsion work?   
   >>   
   >> I am aware of nuclear batteries that generate electricity.   
   >> Am aware of nuclear reactors that heat water into steam and drive   
   >> turbines.  But how is nuclear fission used as propulsion?   
   >   
   > There are several different methods. But basically, if you heat a gas to   
   > high temperature, whether you heat it by chemical reactions, nuclear   
   > energy or some other method, the gas wants to expand. You just have to   
   > make sure that the expansion happens in the opposite direction to where   
   > you want the rocket to go.   
      
   There's also nuclear-electric propulsion, where you use nuclear energy   
   to generate electrical power for an ion drive. This is more efficient in   
   propellant, but I believe the problem here is to get rid of the waste   
   heat from the fission-to-electricity step -- large radiators may be needed.   
      
   --- SoupGate-Win32 v1.05   
    * Origin: you cannot sedate... all the things you hate (1:229/2)