Speaker
Description
One of the biggest technological challenges in making interstellar precursor missions
feasible is developing an efficient propulsion system. Although several innovative
propulsion concepts have been proposed, none have yet provided a conclusive,
near-term solution. Therefore, it is realistic to assume that such solutions, if they
exist, will likely not be implemented for several decades. As a result, it is sensible to
consider missions to the outer reaches of the solar system that use extensions of
existing technologies.
A crucial parameter for propulsion in interstellar precursor missions is the specific
impulse. To reduce the propellant mass and, consequently, the spacecraft mass to
manageable levels, the specific impulse needs to be significantly higher than what
current high-efficiency ion thrusters can achieve.
Field Emission Electric Propulsion (FEEP) presents several unique advantages: it
offers very high specific impulse (> 4,000 seconds), is the most efficient method for
carrying propellant in solid form (as Indium, which is used, melts at around 157°C), it
has very low thermal losses because the emitter electrode is kept just above
Indium's melting point, and it has a negligible electrode erosion.
Over the past two decades, Fotec GmbH and Enpulsion GmbH have developed and
refined FEEP technology using porous tungsten emitter crowns, establishing it as a
reliable space propulsion solution. More than 150 thrusters have been successfully
deployed and are currently operational in space. Ground tests have shown that
these thrusters can operate continuously for over 50,000 hours with minimal
performance degradation. This exceptional longevity is crucial for the viability of
interstellar precursor missions.
This paper proposes a short-term interstellar demonstration mission, Ikaros2; it is a
NanoSat Spacecraft with Off-the-Shelf Indium FEEP Technology and a deployable
solar array in order to increase the maximum power available for propulsion.
2
The mission main goal is the exploitation of increased solar radiation flux by first
going towards the Sun and building up momentum thanks to the so called Oberth-
effect. After launch, the FEEP propulsion system is used to lower the perihelion by
thrusting in anti-flight direction, but not lower than 0.7 AU thus avoiding the need for
a heavy thermal shield. Close to perihelion, when the solar panels provide maximum
electrical power to the propulsion system, the probe is accelerated with maximum
thrust.
This mission can demonstrate the Oberth maneuver using Electric Propulsion for the
first time, paving the way for more challenging interstellar precursor missions similar
to the one proposed by Loeb et al in 2011.
Loeb, H. W., et al., An Interstellar-Heliopause Mission Using a Combination of
Solar/Radioisotope Electric Propulsion, 32nd International Electric Propulsion Conference,
IEPC-2011-052, Wiesbaden, Germany, Sep. 11-15, 2011
Genovese, A., “Advanced Ion Propulsion Systems for Interstellar Precursor Probes”, Plenary
Talk, Proceedings of Tennessee Valley Interstellar Workshop, Chattanooga, TN, 2016
Genovese, A., Maraqten, N., “Advanced Electric Propulsion Concepts for Fast Missions to
the Outer Solar System and Beyond”, IAC-22,D4,4,3,x73132, Proceedings of the 73rd
International Astronautical Congress (IAC), Paris, France, 18-22 September 2022