re: Destinations & interplanetary travel times
"And as to travel times, only because of utter lack of nerve have we not considered nuclear electric VASIMR drive spacecraft, craft that could reach Mars in under 90 days."
Well, these guys seem to want to do it without nukes:
http://www.adastrarocket.com/missions.html
If seems there going to use solar panels and/or beamed energy:
Suppose you had a payload of 100 tons, and you wanted to accelerate it at the perigee of a highly elliptical orbit. How much beamed energy would that require if you wanted 90 day transfer to Mars?
Assuming you could get significantly less energy- beamed or from solar panels per minute for decelerating as you approached Mars?