The technological and commercial expansion of electric propulsion

The use of Electric Propulsion (EP) on satellites for commercial, defense, and space science missions has been increasing in recent decades, from the first successful operation in 1964 aboard the Zond-2 spacecraft to the present day. This paper provides an overview of the technological and commercial development of EP systems that have been deployed. A review of the early years of EP application ends in 1980, when the first geostationary commercial satellite using EP, Intelsat-V, was launched. Beyond 1980, all EP-based spacecraft deployment data through 2018 are presented, divided by spacecraft type: GEO-synchronous satellite, LEO satellites, deep-space missions and small satellites. To date, a total of 587 spacecraft have been launched with some variant of electric propulsion. During the 1960s and 1970s, all 48 spacecraft using EP were government missions, with the US and USSR leading in the development, production, and flight of these systems. These first platforms included a variety of pulsed plasma thrusters, resistojets, arcjets, ion thrusters and Hall thrusters. The number of GEO satellites with electric propulsion systems has increased significantly since 1981, from an average of less than 5 satellites per year during the 1980s to over 15 in recent years. The corresponding annual fraction of EP based GEO satellite launches, compared to all GEO satellite launches, has increased from 20% during the 1980s to over 40% in recent years. For LEO applications, a gradual increase in the utilization of EP has been realized. Of the 167 EP-based LEO platforms deployed, resistojets were the most prolific legacy thruster type (124 S/C) with Hall thrusters gaining traction in recent years (25 S/C), appearing on 19 of 45 satellite missions in the past decade. Of all EP-based LEO missions, approximately half served as testbeds for new technologies. Through 2018, eight deep space spacecraft with EP have been launched, with the US, Japan, and the European Union leading these efforts. Small satellites are also benefiting from this technology, with 24 EP-based small satellites launched to date. Nearly half of these were launched between 2016 and 2018, demonstrating accelerated growth and a large potential for the future of this spacecraft class.