https://www.nasa.gov/directorates/space ... ropulsion/
Space exploration is hindered by the limitations of rocket equation. Indeed, only two space probes have left the heliosphere and entered the interstellar medium. It took Voyager 1 cruising at a record breaking velocity of 3.6 AU/year 35 years to reach the heliopause. Pellet-beam aims to transform the way deep space is explored by enabling fast transit missions to far away destinations. With the pellet-beam outer planets can be reached in less than a year, 100 AU in about 3 year and solar gravity lens at 500 AU in about 15 years. Importantly, unlike other concepts pellet beam allows propelling heavy spacecraft (~1 ton) which substantially increases the scope of possible missions.