There are a number of pressing problems mankind is facing today that could, at least in part, be resolved by space systems. These include capabilities for fast and far-reaching telecommunication, surveying of resources and climate, and sustaining global information networks, to name but a few. Not surprisingly, increasing efforts are now devoted to building a strong near-Earth satellite infrastructure, with plans to extend the sphere of active life to orbital space and, later, to the Moon and Mars if not further. The realization of these aspirations demands novel and more efficient means of propulsion. At present, it is not only the heavy launch systems that are fully reliant on thermodynamic principles for propulsion. Satellites and spacecraft still widely use gas-based thrusters or chemical engines as their primary means of propulsion. Nonetheless, similar to other transportation systems where the use of electrical platforms has expanded rapidly, space propulsion technologies are also experiencing a shift toward electric thrusters that do not feature the many limitations intrinsic to the thermodynamic systems. Most importantly, electric and plasma thrusters have a theoretical capacity to deliver virtually any impulse, the latter being ultimately limited by the speed of light. Rapid progress in the field driven by consolidated efforts from industry and academia has brought all-electric space systems closer to reality, yet there are still obstacles that need addressing before we can take full advantage of this promising family of propulsion technologies. In this paper, we briefly outline the most recent successes in the development of plasma-based space propulsion systems and present our view of future trends, opportunities, and challenges in this rapidly growing field.

The renewed interest in space exploration has led to the growth in research efforts pertaining to advanced space propulsion systems, including highly efficient electric propulsion systems. Although already tested in space many decades ago and being currently employed on various space platforms and thousands of satellites, these systems are yet to reach their full potential for applications on orbit and in deep space. One specific feature of space electric propulsion is the large diversity of physical processes used in this technology, which is not typical for many other types of propulsion systems used in transport, such as those used by airplanes or automobiles. Various physical processes and mechanisms underpin different electric propulsion technologies and should be integrated to drive the future science and technology of space electric propulsion systems. This opinion article briefly highlights this feature of space electric propulsion and outlines some challenges and opportunities that follow from this diversity.

Hollow cathodes serve as electron sources for the operation of electric thrusters aboard spacecraft. Conventionally, hollow cathodes utilize a heating element to raise the temperature of the electron emitting material embedded in the cathode. To simplify cathode design and operation, in recent years, heaterless cathode technology has been under development in various facilities around the world. This paper overviews the development of a low current heaterless hollow cathode, designed and produced by Rafael, and denoted the ARC-1A. The ARC-1A generates a discharge current of 0.3–1.2 A and is ignited using breakdown voltages below 400 V. Each of the development phases is elaborated upon. These phases included activities such as a technology study, the development of manufacturing processes, the study of failure modes, and performance characterization and culminated with two primary tests—a 5000 h endurance test and a 3500 cold ignition cycles test. In its current state of development, the ARC-1A proves suitable for a wide range of low power electric thrusters and was successfully coupled with two different Hall effect thrusters in a wide range of low discharge current levels (0.5–1.1 A).