Space micropropulsion systems for Cubesats and small satellites: From proximate targets to furthermost frontiers

Abstract

Rapid evolution of miniaturized, automatic, robotized, function-centered devices has redefined space technology, bringing closer the realization of most ambitious interplanetary missions and intense near-Earth space exploration. Small unmanned satellites and probes are now being launched in hundreds at a time, resurrecting a dream of satellite constellations, i.e., wide, all-covering networks of small satellites capable of forming universal multifunctional, intelligent platforms for global communication, navigation, ubiquitous data mining, Earth observation, and many other functions, which was once doomed by the extraordinary cost of such systems. The ingression of novel nanostructured materials provided a solid base that enabled the advancement of these affordable systems in aspects of power, instrumentation, and communication. However, absence of efficient and reliable thrust systems with the capacity to support precise maneuvering of small satellites and CubeSats over long periods of deployment remains a real stumbling block both for the deployment of large satellite systems and for further exploration of deep space using a new generation of spacecraft. The last few years have seen tremendous global efforts to develop various miniaturized space thrusters, with great success stories. Yet, there are critical challenges that still face the space technology. These have been outlined at an inaugural International Workshop on Micropropulsion and Cubesats, MPCS-2017, a joint effort between Plasma Sources and Application Centre/Space Propulsion Centre (Singapore) and the Micropropulsion and Nanotechnology Lab, the G. Washington University (USA) devoted to miniaturized space propulsion systems, and hosted by CNR-Nanotec—P.Las.M.I. lab in Bari, Italy. This focused review aims to highlight the most promising developments reported at MPCS-2017 by leading world-reputed experts in miniaturized space propulsion systems. Recent advances in several major types of small thrusters including Hall thrusters, ion engines, helicon, and vacuum arc devices are presented, and trends and perspectives are outlined.

Control of electron, ion and neutral heating in a radio-frequency electrothermal microthruster via dual-frequency voltage waveforms

“…Despite the odd-odd waveform having applied no direct electrical asymmetry to the plasma, there was still a non-zero modulation in the dc self-bias voltage, 5 (a). The mechanism for this modulation is attributed to the variation in the peak-to-peak voltage (2) and associated variation in the power deposited with phase offset, see figure 5 (b). The increased rf-power deposition in figure 5 (b) coincides with an increased ionization rate adjacent to the powered electrode in figure 5 (c).…”

Advanced Materials for Next‐Generation Spacecraft

“…While self‐healing is possibly the most attractive feature that the advanced materials could introduce at the “spacecraft level” (with the adaptivity and multi‐functionality being a secondary feature), the situation may change when advanced materials are discussed in relation to space thrusters, and specifically, electric propulsion thrusters that are undoubtedly the most promising type of propulsors for the future advanced and miniaturized spacecraft . Various mission segments require different characteristics of a thrust system, and this is currently achieved by the use of a set of different thrusters installed on the spacecraft.…”

“…Multi‐modal operation is still a challenge but advanced, nanostructured materials may be a solution capable of transforming the space thrust technology. [40a] On the other hand, the life of space thrusters still remains the issue and should be adequately addressed, with self‐healing still being of a paramount importance.…”

Mars Colonization: Beyond Getting There

“…Proponents of Mars colonization consider present space technology as nearing the stage when it will be able to provide the necessary level of reliability and efficiency required for the one way journey from Earth to Mars. Indeed, a recent example of successful firing of thrusters on Voyager 1 after 37 years of space operation attests to our ability to overcome such significant challenges of spacecraft development as longevity, reliability, and operational readiness decades after launching. Ongoing advances in nanotechnology and materials engineering enhanced reliability and expanded functionality of contemporary electronics and robotics while reducing device mass, volume, and power consumption .…”