Topical Collection "Micro-Propulsion Systems and Components for Small Spacecraft—Current Trends, Innovations and Challenges"

Editors

Guest Editor
Prof. Dr. Darren L. Hitt

Department of Mechanical Engineering, The University of Vermont, Burlington, VT 05405, USA
Website | E-Mail
Interests: small spacecraft propulsion and engineering; orbital mechanics; micro-scale thermofluid engineering
Guest Editor
Dr. Angelo Cervone

Department of Space Engineering, Aerospace Engineering Faculty, Delft University of Technology, Kluyverweg 1, 2629 HS Delft, The Netherlands
Website | E-Mail
Interests: space propulsion; small spacecraft design; space systems engineering; miniaturization of space systems and components

Topical Collection Information

Dear Colleagues,

Miniaturized spacecraft in the nano-satellite class, such as CubeSats or PocketQubes, are making access to space more and more easy, fast, and cheap, especially with the recent developments in miniaturization technologies. Simplification of the satellite infrastructure and use of off-the shelf electronic components make it possible to design and produce a working satellite at low cost. As a consequence, although this class of spacecraft were initially used mostly in Academic projects, they are rapidly attracting attention of research institutions and companies for specific commercial applications.

However, a limit on the exponential growth that small satellite launches have shown in recent years is posed by the relatively small number of available dedicated propulsion systems. Propulsive capabilities are fundamental for these platforms to totally realize their potential, allowing them to engage in a wider range of missions such as those characterized by many satellites flying in formation or in a constellation, possibly even in low altitude orbits. The strict mass, volume, and power limitations typically imposed by small satellite requirements make it impossible to simply scale down “conventional” propulsion systems: completely different, and often unique, micro-technologies are needed to help develop a compliant propulsion system, including Micro-ElectroMechanical Systems (MEMS) and high level component integration. Therefore, research on micro-propulsion systems for small satellites is currently a very “hot”, active and innovative field, which involves a large number of universities and companies. This Special Issue will host a selection of advanced developments in the field, related to any kind of micro-propulsion concept.

Authors are encouraged to submit manuscripts on analytical, numerical, design, test or integration activities of micro-propulsion systems for small spacecraft. Proposed papers can either relate to the complete system or specific components of it (nozzle, thruster, valves, sensors, tank, power conditioning, propellants, fluidic lines, etc.). Contributions on chemical, cold gas, electric or electro-thermal propulsion are welcome, as well as advanced propulsion concepts.

Prof. Darren L. Hitt
Dr. Angelo Cervone
Guest Editors

Manuscript Submission Information

Manuscripts should be submitted online at www.mdpi.com by registering and logging in to this website. Once you are registered, click here to go to the submission form. Manuscripts can be submitted until the deadline. All papers will be peer-reviewed. Accepted papers will be published continuously in the journal (as soon as accepted) and will be listed together on the collection website. Research articles, review articles as well as short communications are invited. For planned papers, a title and short abstract (about 100 words) can be sent to the Editorial Office for announcement on this website.

Submitted manuscripts should not have been published previously, nor be under consideration for publication elsewhere (except conference proceedings papers). All manuscripts are thoroughly refereed through a single-blind peer-review process. A guide for authors and other relevant information for submission of manuscripts is available on the Instructions for Authors page. Aerospace is an international peer-reviewed open access quarterly journal published by MDPI.

Please visit the Instructions for Authors page before submitting a manuscript. The Article Processing Charge (APC) for publication in this open access journal is 550 CHF (Swiss Francs). Submitted papers should be well formatted and use good English. Authors may use MDPI's English editing service prior to publication or during author revisions.

Keywords

  • micro-propulsion;
  • small spacecraft;
  • CubeSats;
  • miniaturization of space systems and components

Published Papers (6 papers)

2018

Jump to: 2017

Open AccessArticle A Dual Mode Propulsion System for Small Satellite Applications
Received: 6 February 2018 / Revised: 11 April 2018 / Accepted: 26 April 2018 / Published: 2 May 2018
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Abstract
This study focused on the development of a chemical micropropulsion system suitable for primary propulsion and/or attitude control for a nanosatellite. Due to the limitations and expense of current micropropulsion technologies, few nanosatellites with propulsion have been launched to date; however, the availability
[...] Read more.
This study focused on the development of a chemical micropropulsion system suitable for primary propulsion and/or attitude control for a nanosatellite. Due to the limitations and expense of current micropropulsion technologies, few nanosatellites with propulsion have been launched to date; however, the availability of such a propulsion system would allow for new nanosatellite mission concepts, such as deep space exploration, maneuvering in low gravity environments and formation flying. This work describes the design of “dual mode” monopropellant/bipropellant microthruster prototype that employs a novel homogeneous catalysis scheme. Results from prototype testing are reported that validate the concept. The micropropulsion system is designed to be fabricated using a combination of additively-manufactured and commercial off the shelf (COTS) parts along with non-toxic fuels, thus making it a low-cost and environmentally-friendly option for future nanosatellite missions. Full article
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Graphical abstract

Open AccessArticle Prilling and Coating of Ammonium Dinitramide (ADN) Solid Green Propellant in Toluene Mixture Using Ultrasound Sonication
Received: 18 December 2017 / Revised: 6 March 2018 / Accepted: 7 March 2018 / Published: 9 March 2018
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Abstract
Ammonium Dinitramide (ADN) in its generic form has a long needle shaped structure, which hinders higher solid loading. Therefore, it is of utmost importance to optimize its crystal morphology into octagonal shapes. Moreover, the low critical humidity level of ADN renders it unusable
[...] Read more.
Ammonium Dinitramide (ADN) in its generic form has a long needle shaped structure, which hinders higher solid loading. Therefore, it is of utmost importance to optimize its crystal morphology into octagonal shapes. Moreover, the low critical humidity level of ADN renders it unusable in a humid climate. Hence, encapsulation with a hydrophobic polymer is necessary. In the present work, ADN was synthesized by nitration of potassium sulfamate with mixed acid nitration. The product was then mixed with toluene, graphene, citryl ammonium butyl, Cab-o-sil, and coating polymer (Polystyrene or HTPB) and treated with ultrasound to obtain semi-spherical ADN-coated particles. The method offers a reduction in operating temperature and elimination of ADN melting in the shape-altering process. In addition, the ADN product has a similar particle size and thermal stability compared to those in a conventional ADN melt-prilling method. The ADN product investigated under SEM confirms the particle morphological change from long needles into semi-spherical shapes. The particle size obtained, in the micrometer range, is ideal for higher theoretical maximum density. Furthermore, the ultrasound-treated ADN particles show significant reduction in moisture absorption, from 68% to 16% at 65% relative humidity. The DSC result shows no degradation of thermal stability of the coated particles. Full article
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Graphical abstract

Open AccessArticle Mathematical Modeling of Liquid-fed Pulsed Plasma Thruster
Received: 19 December 2017 / Revised: 16 January 2018 / Accepted: 18 January 2018 / Published: 22 January 2018
Cited by 1 | PDF Full-text (1240 KB) | HTML Full-text | XML Full-text
Abstract
Liquid propellants are fast becoming attractive for pulsed plasma thrusters due to their high efficiency and low contamination issues. However, the complete plasma interaction and acceleration processes are still not very clear. Present paper develops a multi-layer numerical model for liquid propellant PPTs
[...] Read more.
Liquid propellants are fast becoming attractive for pulsed plasma thrusters due to their high efficiency and low contamination issues. However, the complete plasma interaction and acceleration processes are still not very clear. Present paper develops a multi-layer numerical model for liquid propellant PPTs (pulsed plasma thrusters). The model is based on a quasi-steady flow assumption. The model proposes a possible acceleration mechanism for liquid-fed pulsed plasma thrusters and accurately predicts the propellant utilization capabilities and estimations for the fraction of propellant gas that is completely ionized and accelerated to high exit velocities. Validation of the numerical model and the assumptions on which the model is based on is achieved by comparing the experimental results and the simulation results for two different liquid-fed thrusters developed at the University of Tokyo. Simulation results shows that up-to 50 % of liquid propellant injected is completely ionized and accelerated to high exit velocities (>50 Km/s), whereas, neutral gas contribute to only 7 % of the total specific impulse and accelerated to low exit velocity (<4 Km/s). The model shows an accuracy up-to 92 % . Optimization methods are briefly discussed to ensure efficient propellant utilization and performance. The model acts as a tool to understand the background physics and to optimize the performance for liquid-fed PPTs. Full article
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2017

Jump to: 2018

Open AccessArticle Molecular Dynamics Electrospray Simulations of Coarse-Grained Ethylammonium Nitrate (EAN) and 1-Ethyl-3-Methylimidazolium Tetrafluoroborate (EMIM-BF4)
Received: 30 September 2017 / Revised: 20 December 2017 / Accepted: 25 December 2017 / Published: 28 December 2017
PDF Full-text (3888 KB) | HTML Full-text | XML Full-text | Supplementary Files
Abstract
In this work, the use of molecular dynamics as a predictive tool for modeling the atomistic behavior of electrospray propulsion is discussed. 1-ethyl-3-methylimidazolium tetrafluoroborate (EMIM-BF4) and ethylammonium nitrate (EAN) were considered as two limits of ionic liquid (IL) propellants that tend
[...] Read more.
In this work, the use of molecular dynamics as a predictive tool for modeling the atomistic behavior of electrospray propulsion is discussed. 1-ethyl-3-methylimidazolium tetrafluoroborate (EMIM-BF 4 ) and ethylammonium nitrate (EAN) were considered as two limits of ionic liquid (IL) propellants that tend to operate in an ion versus a droplet mode. The emission modes were found to depend on the electro-chemical properties of the IL propellant. The aprotic EMIM-BF 4 -based electrospray emitted primarily monomers and trimers as the dominant species and only small quantities of droplets. In contrast, trimers were the dominant emitted species in the protic EAN emissions with a significantly large contribution from droplets towards the total emission current, suggesting that EMIM-BF 4 -based colloid thrusters operate in ion mode and EAN-based devices operate in the droplet mode. Furthermore, the formation of the Taylor cone was found to depend on the mass flow rate and the external electric field strength. This paper provides a framework that can be extended for use to simulate any other ILs or their combinations. Full article
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Open AccessReview An Overview of Cube-Satellite Propulsion Technologies and Trends
Received: 30 September 2017 / Revised: 21 November 2017 / Accepted: 29 November 2017 / Published: 9 December 2017
Cited by 2 | PDF Full-text (889 KB) | HTML Full-text | XML Full-text
Abstract
CubeSats provide a cost effective means to perform scientific and technological studies in space. Due to their affordability, CubeSat technologies have been diversely studied and developed by educational institutions, companies and space organizations all over the world. The CubeSat technology that is surveyed
[...] Read more.
CubeSats provide a cost effective means to perform scientific and technological studies in space. Due to their affordability, CubeSat technologies have been diversely studied and developed by educational institutions, companies and space organizations all over the world. The CubeSat technology that is surveyed in this paper is the propulsion system. A propulsion system is the primary mobility device of a spacecraft and helps with orbit modifications and attitude control. This paper provides an overview of micro-propulsion technologies that have been developed or are currently being developed for CubeSats. Some of the micro-propulsion technologies listed have also flown as secondary propulsion systems on larger spacecraft. Operating principles and key design considerations for each class of propulsion system are outlined. Finally, the performance factors of micro-propulsion systems have been summarized in terms of: first, a comparison of thrust and specific impulse for all propulsion systems; second, a comparison of power and specific impulse, as also thrust-to-power ratio and specific impulse for electric propulsion systems. Full article
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Open AccessArticle High Fidelity Multi-Objective Design Optimization of a Downscaled Cusped Field Thruster
Received: 27 September 2017 / Revised: 1 November 2017 / Accepted: 11 November 2017 / Published: 18 November 2017
PDF Full-text (7456 KB) | HTML Full-text | XML Full-text
Abstract
The Cusped Field Thruster (CFT) concept has demonstrated significantly improved performance over the Hall Effect Thruster and the Gridded Ion Thruster; however, little is understood about the complexities of the interactions and interdependencies of the geometrical, magnetic and ion beam properties of the
[...] Read more.
The Cusped Field Thruster (CFT) concept has demonstrated significantly improved performance over the Hall Effect Thruster and the Gridded Ion Thruster; however, little is understood about the complexities of the interactions and interdependencies of the geometrical, magnetic and ion beam properties of the thruster. This study applies an advanced design methodology combining a modified power distribution calculation and evolutionary algorithms assisted by surrogate modeling to a multi-objective design optimization for the performance optimization and characterization of the CFT. Optimization is performed for maximization of performance defined by five design parameters (i.e., anode voltage, anode current, mass flow rate, and magnet radii), simultaneously aiming to maximize three objectives; that is, thrust, efficiency and specific impulse. Statistical methods based on global sensitivity analysis are employed to assess the optimization results in conjunction with surrogate models to identify key design factors with respect to the three design objectives and additional performance measures. The research indicates that the anode current and the Outer Magnet Radius have the greatest effect on the performance parameters. An optimal value for the anode current is determined, and a trend towards maximizing anode potential and mass flow rate is observed. Full article
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