This article was updated on Aug. 26, 2020, with information on the thruster patent.
LOGAN, Utah – The University Würzburg announced at the Small Satellite Conference that onboard electric thrusters from the Institute of Aerospace Engineering of Technical University Dresden changed the attitude of a cubesat measuring ten centimeters on a side, a first for such a miniature satellite.
“This was the official proof that our thrusters work in space,” said István Lőrincz, co-founder of Morpheus Space, a spinoff of the Institute of Aerospace Engineering of Technical University Dresden. Morpheus Space co-founder Daniel Bock was one of three Technical University Dresden inventors who patented the Field Effect Electric Propulsion technology. Morpheus Space is developing and manufacturing similar electric thrusters.
The University Würzburg Experimental Satellite 4 has four 160-gram Nano Field Effect Electric Propulsion (NanoFEEP) thrusters integrated in its rails, facing the same direction. In May, mission controllers fired the thrusters, which combine a liquid gallium propellant with a chip-based neutralizer, for slightly more than six minutes.
While the thrusters fired, the satellite’s rotation increased from approximately 1.7 degrees per second to more than four degrees per second, according to “Hybrid attitude control on-board UWE-4 using magnetorquers and the electric propulsion system NanoFEEP,” by Alexander Kramer, Philip Bangert and Klaus Schilling of University Würzburg.
In the weeks ahead, the University Würzburg plans to continue testing the miniature thrusters. “There are a lot of test planned including orbit change and also a simulated collision avoidance maneuver,” Lőrincz told SpaceNews.
Companies are racing to develop miniature technologies for cubesats. One of the most challenging to produce is a miniature propulsion system.
“The challenge lies partly in the electronics and partly in the materials,” Lőrincz said. NanoFEEP thrusters generate high voltage in a very small space.”
During the recent on-orbit demonstration, the thrusters did not produce thrust in a single direction as expected. A portion of the ion plume created by the thrusters hit the cubesat antenna, creating “a torque in an undesired direction,” according to the paper published Aug. 3 at the Small Satellite Conference.
In spite of that issue, the authors note, “A milestone in the 1U cubeSat development was reached with the activation of an electric propulsion system,” in the paper.