Special Issue "Green Propulsion: Present Solutions and Perspectives for Powering Environmentally Friendly Space Missions"

A special issue of Aerospace (ISSN 2226-4310). This special issue belongs to the section "Astronautics & Space Science".

Deadline for manuscript submissions: 15 January 2023 | Viewed by 12353

Special Issue Editors

Prof. Dr. Filippo Maggi
E-Mail Website
Guest Editor
Dipartimento di Scienze e Tecnologie Aerospaziali, Politecnico di Milano, 20133 Milano, Italy
Interests: composite solid propellants, liquid storable propellants; metal fuels; green propulsion, launch systems
Prof. Dr. Paravan Christian
E-Mail Website
Guest Editor
Dipartimento di Scienze e Tecnologie Aerospaziali, Politecnico di Milano, Milan, Italy
Interests: hybrid rocket propulsion; metal combustion; nano-sized materials; green propellants

Special Issue Information

Dear Colleagues,

Humankind has largely benefitted from space activities and related technologies. The outcomes of those activities and technologies are currently an essential part of our daily lives, granting us services, safety, rapid emergency response, and scientific improvements. Space industry is substantially growing thanks to new private actors entering the market and leading to cost reduction for launch services and space platform development. This trend, deemed to rise further due to the commercial exploitation of Earth orbits, brings several concerns about the effective environmental sustainability of the space sector. Thermochemical propulsion is considered one of the factors for improvement.

The environmental impact of space propulsion includes short- and long-term effects on humans and on the environment. These are caused by propellant production, handling, storage, use, and disposal, during both normal operating conditions (e.g., exhaust products, tank venting) and emergency situations (i.e., catastrophic launch failure and consequent on-ground propellant contamination).

There is not a rigid definition of “green propulsion,” so under this classification a wide range of research and development activities are gathered. Space agencies and institutions are supporting specific initiatives, development plans, and solutions aiming at improving the sustainability of the space sector in both short and long-term perspectives, in compliance with the UN Sustainable Development Goals. NASA’s “Green Propulsion Technology Development Roadmap” and ESA’s “CleanSpace” initiatives represent only two examples of this global cooperative R&D effort in which agencies, industries, and the academy are active actors.

This Special Issue aims to collect contributions in the area of the thermochemical propulsion for launchers and spacecraft operations, focusing on the assessment and on the reduction of the environmental impact deriving from propulsion systems. Potential topics include, but are not limited to:

  • Impact evaluation of current propellants and related propulsion technology solutions on environment and involved workers
  • Literature surveys, trade-off analyses, and evaluation studies on green propulsion solutions for spacecraft and launchers
  • Experimental/numerical/theoretical activities related to green propulsion developments
  • Solid, liquid (storable, cryogenic), hybrid thermochemical propulsion systems aiming at improving the sustainability of current and future space industry
  • Peculiarities and relevant aspects characterizing the combustion processes of propellants for green propulsion systems
  • Issues and improvements related to propellant lifecycle (production, handling, storage, disposal, and emergency management)
  • Evaluation of short- and long-term effects of combustion products on environment and humans (e.g. plume, acid rains, groundwater pollution, toxicological effects, etc.)
  • Status advancement/final conclusions of projects, or part of them, concerning green propulsion topics.

Prof. Dr. Filippo Maggi
Prof. Dr. Paravan Christian
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 submissions that pass pre-check are peer-reviewed. Accepted papers will be published continuously in the journal (as soon as accepted) and will be listed together on the special issue 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 monthly 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 1600 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

  • green propulsion
  • solid propulsion
  • liquid propulsion
  • hybrid propulsion
  • propellant
  • pollution
  • environmental impact
  • space industry
  • clean technologies

Published Papers (5 papers)

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Research

Article
Emission-Driven Hybrid Rocket Engine Optimization for Small Launchers
Aerospace 2022, 9(12), 807; https://doi.org/10.3390/aerospace9120807 - 09 Dec 2022
Abstract
Hybrid rocket engines are a green alternative to solid rocket motors and may represent a low-cost alternative to kerosene fueled rockets, while granting performance and control features similar to that of typical storable liquid rocket engines. In this work, the design of a [...] Read more.
Hybrid rocket engines are a green alternative to solid rocket motors and may represent a low-cost alternative to kerosene fueled rockets, while granting performance and control features similar to that of typical storable liquid rocket engines. In this work, the design of a three-stage hybrid launcher is optimized by means of a coupled procedure: an evolutionary algorithm optimizes the engine design, whereas an indirect optimization method optimizes the corresponding ascent trajectory. The trajectory integration also provides the vertical emission profiles required for the evaluation of the environmental impact of the launch. The propellants are a paraffin-based wax and liquid oxygen. The vehicle is launched from the ground and uses an electric turbo pump feed system. The initial mass is given (5000 kg) and the insertion of the payload into a 600-km circular, and polar orbit is considered as a reference mission. Clusters of similar hybrid rocket engines, with only few differences, are employed in all stages to reduce the development and operational costs of the launcher. Optimization is carried out with the aim of maximizing the payload mass and then minimizing the overall environmental impact of the launch. The results show that satisfactory performance is achievable also considering rocket polluting emissions: the carbon footprint of the launch can be reduced by one fourth at the cost of a 5-kg payload mass reduction. Full article
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Article
Evaluating New Liquid Storable Bipropellants: Safety and Performance Assessments
Aerospace 2022, 9(10), 561; https://doi.org/10.3390/aerospace9100561 - 28 Sep 2022
Viewed by 1184
Abstract
Conventional storable bipropellants make use of hydrazine and its derivatives as fuels and nitrogen tetroxide as an oxidizer. In recent years, the toxicity character of these chemicals pushed the propulsion community towards “green” alternatives. Several candidates have been proposed among existing and newly [...] Read more.
Conventional storable bipropellants make use of hydrazine and its derivatives as fuels and nitrogen tetroxide as an oxidizer. In recent years, the toxicity character of these chemicals pushed the propulsion community towards “green” alternatives. Several candidates have been proposed among existing and newly developed chemicals, highlighting the need for a common and robust selection methodology. This paper aims at reviewing the most important selection criteria in the field of toxicity and discusses how to objectively define a green propellant, considering both the health and environmental hazards caused by the chemicals. Additionally, consistent figures of merit in the field of safety and handling operations and performance are proposed. In particular, operating temperatures, flammability and stability issues are discussed in the framework of physical hazards and storage requirements, while vacuum impulses, adiabatic flame temperature and sooting occurrence of the investigated couples are compared to the UDMH/NTO benchmark case. Hydrogen peroxide and nitrous oxide, and light hydrocarbons, alcohols and kerosene are selected from the open literature as promising green oxidizers and fuels, respectively. The identified methodology highlights merits and limitations of each chemical, as well as the fact that the identification of a universally best suited green couple is quite impractical. On the contrary, the characteristics of each propellant lead to a scenario of several “sub-optimal” couples, each of them opportunely fitting into a specific mission class. Full article
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Article
Development of POLON—A Green Microsatellite Propulsion Module Utilizing 98% Hydrogen Peroxide
Aerospace 2022, 9(6), 297; https://doi.org/10.3390/aerospace9060297 - 31 May 2022
Viewed by 1297
Abstract
The following paper presents the key design and test activities associated with the development of POLON—a green microsatellite propulsion module using 98% Hydrogen Peroxide (HTP). POLON, which stands for “Polish Propulsion Module”, is the first step toward the development of a full, ready-to-be-commercialized [...] Read more.
The following paper presents the key design and test activities associated with the development of POLON—a green microsatellite propulsion module using 98% Hydrogen Peroxide (HTP). POLON, which stands for “Polish Propulsion Module”, is the first step toward the development of a full, ready-to-be-commercialized satellite propulsion system at the Łukasiewicz—Institute of Aviation (Ł-IoA). The development of an entire microsatellite propulsion system within the frame of the POLON project effort is the natural milestone on the Ł-IoA green propulsion roadmap, which so far embodied research on fundamental HTP chemistry, work on elementary propulsion technologies, as well as the development of individual propulsion components. Within this article, POLON propulsion development logic is introduced first, and the major challenges associated with utilizing HTP for an orbital propulsion system are described. Consequently, the specific R&D activities aimed at mitigating the identified issues and risks are discussed. Those cover analytical as well as experimental work, including, but not limited to, HTP compatibility studies with candidate construction materials, waterhammer effect studies, HTP catalyst testing and evaluation, and propellant tank manufacturing studies. The initial results for those activities are presented and, finally, further development plans are discussed. Full article
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Article
Quantitative Clarification of Stable Ignition Region for HKP110 Green Hypergolic Bipropellant
Aerospace 2022, 9(3), 129; https://doi.org/10.3390/aerospace9030129 - 02 Mar 2022
Cited by 1 | Viewed by 1189
Abstract
As a candidate for a green hypergolic bipropellant, the combination of highly concentrated hydrogen peroxide and fuel with dissolved sodium borohydride has been widely studied. In this study, a drop test using such a green hypergolic bipropellant was conducted to investigate the stable [...] Read more.
As a candidate for a green hypergolic bipropellant, the combination of highly concentrated hydrogen peroxide and fuel with dissolved sodium borohydride has been widely studied. In this study, a drop test using such a green hypergolic bipropellant was conducted to investigate the stable ignition region in terms of the mixture ratio. As a result, stagnation phenomena of flame growth were observed in high mixture ratio conditions. In addition, impinging-jet tests using a windowed chamber were conducted with the green hypergolic bipropellant to observe the ignition phenomena inside the combustion chamber. As a result, unstable ignition phenomena were observed in oxidizer-lead injection cases. Besides the unstable ignition, hard starts occurred several times during the test series. Data analysis demonstrated that controlling the transient mixture ratio in the early phase of injection is essential for preventing unstable ignition and hard starts. The quantitative threshold of mixture ratio for stable ignition was clarified based on the test results. Full article
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Article
Modular Impulsive Green Monopropellant Propulsion System (MIMPS-G): For CubeSats in LEO and to the Moon
Aerospace 2021, 8(6), 169; https://doi.org/10.3390/aerospace8060169 - 19 Jun 2021
Cited by 5 | Viewed by 2672
Abstract
Green propellants are currently considered as enabling technology that is revolutionizing the development of high-performance space propulsion, especially for small-sized spacecraft. Modern space missions, either in LEO or interplanetary, require relatively high-thrust and impulsive capabilities to provide better control on the spacecraft, and [...] Read more.
Green propellants are currently considered as enabling technology that is revolutionizing the development of high-performance space propulsion, especially for small-sized spacecraft. Modern space missions, either in LEO or interplanetary, require relatively high-thrust and impulsive capabilities to provide better control on the spacecraft, and to overcome the growing challenges, particularly related to overcrowded LEOs, and to modern space application orbital maneuver requirements. Green monopropellants are gaining momentum in the design and development of small and modular liquid propulsion systems, especially for CubeSats, due to their favorable thermophysical properties and relatively high performance when compared to gaseous propellants, and perhaps simpler management when compared to bipropellants. Accordingly, a novel high-thrust modular impulsive green monopropellant propulsion system with a micro electric pump feed cycle is proposed. MIMPS-G500mN is designed to be capable of delivering 0.5 N thrust and offers theoretical total impulse Itot from 850 to 1350 N s per 1U and >3000 N s per 2U depending on the burnt monopropellant, which makes it a candidate for various LEO satellites as well as future Moon missions. Green monopropellant ASCENT (formerly AF-M315E), as well as HAN and ADN-based alternatives (i.e., HNP225 and LMP-103S) were proposed in the preliminary design and system analysis. The article will present state-of-the-art green monopropellants in the (EIL) Energetic Ionic Liquid class and a trade-off study for proposed propellants. System analysis and design of MIMPS-G500mN will be discussed in detail, and the article will conclude with a market survey on small satellites green monopropellant propulsion systems and commercial off-the-shelf thrusters. Full article
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