My Google dragnet recently scooped up this discussion on the Physics Forums: Space freighters.
It's a lively debate on how planet-to-planet--and more specifically planet-to-orbit--space freighting might be accomplished. I found it full of ideas for the SFR writer.
Magnetic accelerator launch rails?
Mass vs. fuel?
Earth to space tugs?
Yes, worth a quick look.
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Hosted by 5 Science Fiction Romance authors with 8 RWA Golden Heart finals and a RITA final between them. We aim to entertain with spirited commentary on the past, present, and future of SFR, hot topics, and our take on Science Fiction and SFR books, television, movies and culture.