From what I can see on wikipedia [0] the first FEEP to be used in space was in 2018. Proba-3's implementation phase started in 2014 [1]. The choice of thruster

From what I can see on wikipedia [0] the first FEEP to be used in space was in 2018. Proba-3's implementation phase started in 2014 [1]. The choice of thruster technology was probably made well before that. They wouldn't use a technology that hasn't flown yet, unless it was crucial for the mission. [0] https://en.wikipedia.org/wiki/Field-emission_electric_propulsion https://en.wikipedia.org/wiki/Field-emission_electric_propul... [1] https://www.esa.int/Enabling_Support/Space_Engineering_Technology/Proba_Missions/Proba-3_Mission3 https://www.esa.int/Enabling_Support/Space_Engineering_Techn...