Jumping the Gun.

From: sraj [mailto:sraj@...]

> Any hope that a mass driver can be used as a propulsion
> system in a Rocket?

Absolutely. Back in the days of the High Frontier studies, it had been
suggested that mass-driver tugs could push payloads of cargo from LEO to
lunar orbit. Also that mass-driver tugs might go out to asteroids and
bring them (or a portion thereof) back to HEO.

Here are some pictures of mass-driver tugs:
http://members.aol.com/sandycombs/massdriv.jpg
http://members.aol.com/sandycombs/asteroid.jpg from
http://members.aol.com/oscarcombs/settle.htm

and

http://www.ssi.org/assets/images/Ch10p204.gif
http://www.ssi.org/assets/images/Ch10p218.gif
http://www.ssi.org/assets/images/Ch11p226.gif from
http://www.ssi.org/Don_Davis_Artshow.html

> Is it more efficint than a chemical
> propulsion system?

Seems like I remember O'Neill commenting that a mass-driver engine could
have twice the specific impulse of the Space Shuttle's chemical main
engines. But as Rick commented, the big advantage is that they could
use just about anything lying around for reaction mass: oxygen from an
ore-refining operation, regolith from an asteroid, etc..

Regards,

Mike Combs