Back when the web was relatively new (say 1998), NASA&#x27;s Institute for Advanced Concepts (NIAC) had a great page that enumerated most of the exotic alternative launch ideas and presented simple graphics and short formulas on what their problems were.<p>It was back when a much higher portion of people browsing the net could be expected to be relatively technically competent and to care about content and not gloss. Maybe it was removed since it didn&#x27;t come up to some visual standard. Sadly I haven&#x27;t been able to find it on archive.org