Welcome back to our series on Interstellar Travel, where we examine concepts that have been proposed since the dawn of the Space Age. Propulsion ConceptsBased on the many proposals made since the mid-20th century, antimatter propulsion can be grouped into three categories. Next came the work of NASA Jet Propulsion Laboratory (JPL) scientist Robert Frisbee, who described a new concept for antimatter propulsion in a 2003 paper, "How to Build an Antimatter Rocket for Interstellar Missions." Pros & ConsThe advantages of antimatter propulsion are considerable, especially where energy levels and energy efficiency are involved. In summary, it is clear that antimatter propulsion has significant potential for sending future missions to nearby stars.