An extremely lightweight fission rocket could reach the solar gravitational lens in 15 years

Novel propulsion ideas for moving around space seem like they’re a dime a dozen recently. Besides the typical argument between solar sails and chemical propulsion lies a potential third way—a nuclear rocket engine. While we’ve discussed them here at UT before, NASA’s Institute of Advanced Concepts has provided a grant to a company called Positron Dynamics for the development of a novel type of nuclear fission fragment rocket engine (FFRE). It could strike the balance between the horsepower of chemical engines and the longevity of solar sails.