[tim politicus]

Yes I agree, if the process can only be "jump-started" it will eventually grow exponentially of its own momentum. The problem is that darn HUGE startup. The first investrors in both the Panama canal and English colonies in North America lost everything, I think. But once there are accelerators like that in LEO or the moon or in-between...

What really attracted my attention on this thread is a lot of what boris and others were saying about the astronomically (ha ha) better efficiency of chemical over 'electromagnetic propulsion. That got me thinking about railguns as well. Darn problem is the limited acceleration time, even with a vast system.

Are railguns or guns of any significant use at all beyond about a lunar orbit?

To me all what this shows is that it is going to take _a lot_ of work and time and organization and inspiration to get where we need to go. I'd think we need some cultural and social changes before we could pull much of this off.

[RightWhale]

Are railguns or guns of any significant use at all beyond about a lunar orbit?

The old L5 Society was intending to use a lunar railgun to fire incredible amounts of mass to the Lagrangian point where the city would be located. Once it is set up, the ride wouldn't be a big deal; people could probably stand the acceleration. A railgun on earth would have to be huge and would probably serve only for the first stage; a high efficiency second stage such as NERVA would then take over. Cost of launch would be minimal compared to our fire-breathing monsters; cost of construction shouldn't exceed one year of NASA's budget.

The nuclear artillery discussed above might be enough to reach the moon in one shot without bothering with orbits. It wouldn't be man-rated.