Re: World building: implications of counter gravity

On Wed, Nov 08, 2017 at 07:54:48PM +1100, Hugh Fisher wrote:
>My setting is not too distant future. I want easy surface to orbit
launch to
>explain why people are in space, which means using up a lot of energy
on each
>launch.
>
>BUT once in space I want engines to be rather limited, so it isn't easy
to,
>say, divert asteroids into planets.

Er, rockets and ion drives?

All the real-world engine tech we currently know or theorise about has
_either_ good thrust to weight _or_ good specific impulse (thrust per
fuel consumption). (Or neither, but never both.) To get off a planet
you need thrust to weight, but to go between planets you need specific
impulse.

The main thing to avoid is reactionless drives, which IMO rapidly turn
a setting into Asteroid Bombardment War: every spaceship is a
potential WMD.