Nuclear justification for manned spaceflight

| wrote:

I noticed that that all the following posting assume
some form of fission nuclear power. I'll suggest
that fusion might be the 'ultimate' power source
for a grand interplanetary drive. Though it might
need a fission reactor for jump start power. The
ideal would be a deuterium/boron fusion reactor though
that needs much work. Then again aneutronic fusion
maybe too 'Star Trekie' to be practical anytime in
the next century or two.

Until then the best impulse available is from low thrust long running
electric ion drives that have been used on plenty of missions so far.

For such drives the limiting factor is the energy available to power the
drive continuously. Solar cells should be plenty in Earth orbit for
station keeping and orbit maintenance but interplanetary missions would
work far better with more power available. A nuclear reactor could
supply power for both the drive and the rest of the vehicle.

But how to get one safely aloft or enough infrastructure in place to be
able to build one from spaceborn raw materials ...

On May 7, 12:12*am, Doug Freyburger wrote:

*Solar cells should be plenty in Earth orbit for
station keeping and orbit maintenance but interplanetary missions would
work far better with more power available. *A nuclear reactor could
supply power for both the drive and the rest of the vehicle.

But how to get one safely aloft or enough infrastructure in place to be
able to build one from spaceborn raw materials ...

Well as mentioned in a previous post Russia will launch reactors
without problem. If you dont want to launch the fuel from Earth how
about Thorium. You could mine and concentrate it from the Moon.

A thorium reactor has the advantage of needing a particle beam to
operate so if the particle beam is switched off the fuel cant chain
react and have a meltdown, AIUI without the beam the fission slows
until the fuel cools, it's called a sub-critical reactor. Might be a
good safety option for a ship.

Another alternative, is a reactor using Plutonium as the core with
Thorium fuel. There is one running in Moscow. Although, with this you
would need the to have the russians ship the plutonium from Earth at
least.

Maybe the first industry on the Moon will be harvesting and
concetrating Thorium for Space reactors.