AUTHOR=Takahashi Kazunori, Charles Christine, Boswell Rod W., Takao Yoshinori, Fruchtman Amnon, Navarro-Cavallé Jaume, Merino Mario TITLE=Commentary: On helicon thrusters: Will they ever fly? JOURNAL=Frontiers in Physics VOLUME=8 YEAR=2020 URL=https://www.frontiersin.org/articles/10.3389/fphy.2020.00277 DOI=10.3389/fphy.2020.00277 ISSN=2296-424X