I’m not a Luddite as far as most technology goes, but fusion is a scientists’ playground, not an engineering solution to our power needs. Without going into the details yet again, let me just remind you that (1) terrestrial fusion reactors use a somewhat different reaction than the sun; (2) these fusion reactors do produce radioactive waste; and (3) they will always be giant, complex machines that cost way more per megawatt than solar panels and windmills. While fission reactors may be more dangerous than fusion, they are much simpler and have been successfully powering our nuclear submarine fleet for decades. If we ever do have a Mars settlement, it will be powered by fission, not fusion.