In this Phase I study, we propose to analyze the Pluto mission concept using new models of the engine. We will develop an optimal trajectory including limits on the thrust steering and range of throttle. The throttling of the thrust and specific impulse will affect the efficiency, which we have not yet attempted to model.
Direct Fusion Drive is a unique fusion engine concept with a physically feasible approach that would dramatically increase the capability of outer planet missions. The fusion-enabled Pluto mission proposed here is credible, exciting, and the benefits to this and all outer planet missions are difficult to overstate. The truly game-changing levels of thrust and power in a modestly sized package could integrate with our current launch infrastructure while radically expanding the science capability of these missions
There was a 2014 presentation on the Princeton Direct drive fusion concepts. and a work from 2013
• The DFD design envelope fits between traditional chemical, electric and nuclear propulsion methods.
• Fusion products of the deuterium-helium-3 (D/He3) reaction have a very high exhaust velocity: 25,000 km/s
• We can convert some of their kinetic energy into thrust by transferring energy from the fusion products.
The work has been covered at Nextbigfuture back in 2014 and in 2013
This is different than the John Slough's direct fusion drive rocket design. John Slough also had NASA funding.