12-04, 14:40–15:00 (Europe/Luxembourg), Banquet Room
One of the most challenging technologies needed to make interstellar precursor missions practicable is the propulsion system. Several “breakthrough propulsion” concepts have been proposed, but no conclusive results offering a near-term solution to the problem have so far emerged. It is therefore realistic to assume that such solutions, if any, are probably decades away from implementation. It is thus prudent to consider outer-solar system missions employing extensions of existing technologies.
A key propulsion parameter to enable interstellar precursor exploration is the specific impulse; in order to reduce the propellant mass, and consequently the spacecraft mass, to reasonable values, the specific impulse must be much higher than the maximum specific impulse presently achieved by the most efficient ion thrusters.
Field Emission Electric Propulsion (FEEP) offers several unique features: very high specific impulse (> 7,000 s), the most efficient way of carrying propellant (namely in solid state as Indium melts at ~ 157°C), very low thermal losses as the emitter electrode is kept just above 157°C.
Over the past two decades, Fotec GmbH and Enpulsion GmbH have developed and refined FEEP technology based on porous tungsten emitter crowns, elevating it to a well-established space propulsion solution. More than 150 thrusters have been successfully deployed and are currently operational in space. Ground tests have demonstrated that these thrusters can operate for over 50,000 hours with minimal performance degradation. This remarkable lifetime is a critical attribute for the success of interstellar precursor missions.
Recent advancements have led to the successful fabrication and operation of a 2D array of emission points with a single extractor. This achievement is an important stepping stone towards the feasibility of the concept proposed in our previous work (Genovese et al., JBIS, 68, 2015), paving the way for the development of advanced FEEP ion thrusters with high thrust density and ultra-high specific impulse as high as 30,000s.
Furthermore, a short-term interstellar precursor mission based on the present FEEP technology is proposed. Finally, a more challenging mid-term mission could be enabled by the advanced FEEP concept described in this work.
Nembo Buldrini studied Aerospace Engineering at the University of Bologna, Italy, where he obtained his MSc in 1998. In 2001 he moved to Austria. He worked at the AIT as research scientist in the propulsion department until 2010, when the propulsion group was transferred to the company FOTEC GmbH, where he is presently employed. His main activity consists in designing, assembling and testing electric propulsion systems, while keeping an eye on advanced propulsion concepts. He is authour of several articles and patents in the field of space propulsion. Further interests include scientific illustration and graphic arts in general.
