Editing Interstellar travel (section)

===== Fission-fragment =====
[[Fission-fragment rocket]]s use [[nuclear fission]] to create high-speed jets of fission fragments, which are ejected at speeds of up to {{convert|12,000|km/s|mi/s|abbr=on}}. With fission, the energy output is approximately 0.1% of the total mass-energy of the reactor fuel and limits the effective exhaust velocity to about 5% of the velocity of light. For maximum velocity, the reaction mass should optimally consist of fission products, the "ash" of the primary energy source, so no extra reaction mass need be bookkept in the mass ratio.