Giant sails propelled by the sun's or a laser's energy could be the most viable option for interstellar spaceflight in the not-too-distant future, James Benford, a physicist associated with Icarus Interstellar, a non-profit group devoted to finding a way to travel to another star system, said during a panel at the Starship Congress conference in August.

Large and lightweight sails could allow unmanned probes to travel interstellar distances within a somewhat reasonable time frame, Benford said. [How Interstellar Sailing Works (Infographic)]