Exploration of trans-Neptunian objects using the Direct Fusion Drive

The Direct Fusion Drive (DFD) is a nuclear fusion engine that will produce thrust and electrical power for any spacecraft. It is a compact engine, based on the D-He3 aneutronic fusion reaction that uses the Princeton field reversed configuration for the plasma confinement and an odd parity rotating magnetic field as heating method to achieve the fusion. The propellant is deuterium, which is heated by the fusion products and then expanded into a magnetic nozzle, generating an exhaust velocity and thrust. In this work we present possibilities to reach and study the outer border of the solar system using such an engine. The objective is to travel to some trans-Neptunian object (TNO) in the Kuiper belt and beyond, such as the dwarf planets Makemake, Eris and Haumea in less than 10 years with a payload mass of at least of 1000 kg, so that it would enable all kind of missions, from scientific observation, to in-situ operations. Each mission profile chosen is the simplest possible, which is the so-called thrust-coast-thrust profile and for this reason each mission is divided into 3 phases: i. the spiral trajectory to escape Earth gravity from low earth orbit; ii. the interplanetary travel, since the exit from sphere of influence to the end of the coasting phase; iii. maneuvers to rendezvous with the dwarf planet. Propellant mass consumption, initial and final masses, velocities and DeltaV for each maneuver are presented. The analyses of trajectories are performed for two cases: the simplified scenario, in which the TNOs have no inclination on the ecliptic plane and the real scenario, where the real angle of inclination is considered. After that, multiple scenarios have been studied to reach 125 AU in order to enable the study of the external border of the Sun magnetosphere. Our calculations show that a spacecraft propelled by DFD will open unprecedented possibilities to explore the external border of the solar system, in a limited amount of time and with a very high payload to propellant mass.