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This paper analyses the synergy between two innovative technologies: green propellants and electric pump feeding, for a 500 N engine thrust range. The novel approach is then compared to the legacy configuration, i.e., an MMH/NTO pressure fed system. First, a discussion of the benefits and challenges of the different technologies is presented. Subse...
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... Notably, they are classified as group B2 human carcinogens by the World Health Organization (WHO) and the United States. Environmental Protection Agency (USEPA) Research and development of green propellants is the focus of the liquid propellant industry in this century [2][3][4][5]. ...
This study focuses on the application of N,N-dimethylazidoethylamine (DMAZ) as an alternative fuel to the traditional hydrazine fuel. Shortening ignition delay time is the key factor for the DMAZ application. In order to explore the ignition mechanism of DMAZ and NTO, the reaction mechanism between DMAZ and NO2/NTO was studied based on density functional theory (DFT). The results showed that under the conditions of the gas phase and NTO liquid phase, the main path of the reaction is that NO2 attacks the secondary hydrogen atom of DMAZ. The gas-phase reaction enthalpy is higher than that in the NTO liquid phase, indicating that the gas-phase reaction absorbs more energy and is not easy to proceed, while the NTO liquid-phase reaction is easier. The combustion mechanism of DMAZ and NTO was preliminarily obtained. It is speculated that under actual working conditions, DMAZ and NTO mainly undergo the liquid-phase reaction.
... As generally defined, the designation "green propellants" refers to the less-toxic compounds that are storable at ambient temperature and are able to provide acceptable propulsive performances (Marshall and Deans 2013;Gotzig 2017) as cited in Ordonez Valles et al. (2022). However, referring by "green" to most propellants that are not hydrazine is being used currently in many venues. ...
... This wide definition, as explained in Blondel-Canepari et al. (2021), includes a vast number of substances under analysis, such as the ADN-based formulations which are only moderately non-toxic and display a GHS of 3; however, most of the other green monopropellants show lower-toxicity classification of GHS ATC level between 4 and 5, such as N 2 O which is considered non-toxic. Besides the health hazards, the most interesting aspect of aiming toward less-toxic propellants is the drastic reduction in costs of storage and handling by limiting the need for expensive safety procedures, confirmed by Blondel-Canepari et al. (2021) and Ordonez Valles et al. (2022), as mentioned earlier. ...
... Besides the acute toxicity classification, other hazards are regarded when establishing the safety sheet of a chemical compound (Marshall and Deans 2013). Indeed, the GHS final score may be useful for comparing chemicals against each other, however, a more detailed observation regarding different hazard categories should be fulfilled to validate propellants and their applications, as noted in Ordonez Valles et al. (2022). ...
Recent trends in research and development on in-space propulsion have advanced the use of the “green propellants” on an ample scale, mainly eyeing environmental sustainability and especially addressing the handling safety concerns. Small satellites, in particular micro and nanosatellites, have advanced from passive orbiting to having the ability to perform active orbital operations with considerable responsiveness, which tends to call for relatively high-thrust impulsive capabilities. Deep space exploration spacecraft of small size with high ΔV requirements, either intended for Lunar exploration or beyond, necessitate the use of storable propellants to support these relatively high-thrust capabilities, as was seen in several CubeSat missions recently (i.e., 2021 onwards) launched to, or intended for, such missions. Hence, onboard propulsion systems sufficing such requirements, while maintaining the now inevitable environmental sustainability standards, are more sought than before. Green propellants for micro propulsion take a major role and a specific attention in small-sized spacecraft design because of their evident potential in replacing conventional propellants. Green propellants demonstrated comparable, or even higher, performance and above all much less safety concerns in handling, storage, and transportability. Safer-to-handle green propellants reduce a significant financial burden for small and medium-sized enterprises, academic institutions, and innovators who are involved in R&D activities in the field of propulsion systems and space systems development.
... Electric pump feeding has the potential to improve the efficiency of environmentally friendly propellants, hence enabling the substitution of very harmful and poisonous compounds like as hydrazine. This not only promotes safety and sustainability but also provides substantial cost savings in its entirety (Ordonez Valles et al. 2022). Reproduced with modification from Ordonez Valles et al. (2022). ...
... This not only promotes safety and sustainability but also provides substantial cost savings in its entirety (Ordonez Valles et al. 2022). Reproduced with modification from Ordonez Valles et al. (2022). Creative Commons Attribution 4.0 International License (https://creati vecommons.org/licenses/by/4.0). ...
In recent years, extensive research has been conducted globally to explore environmentally friendly alternatives for sustainable energy in space propulsion. Hydrogen peroxide (H2O2) has emerged as a promising green propellant system, particularly for satellite reaction control systems (RCS) and liquid propulsion. This study involved a comprehensive examination of the thermal decomposition of H2O2 monopropellant at a laboratory scale using a batch reactor, a differential pressure device, and differential thermal analysis–gravimetric analysis. The objective was to gain insights into the behavior of this monopropellant before its application in space missions. Concurrently, various catalysts with diverse support shapes were synthesized through different preparation methods. These catalysts were then subjected to characterization using several physico-chemical techniques and evaluated for their effectiveness in facilitating the chemical reactions involved in H2O2 decomposition. Notably, the synthesized catalysts proved to be more cost-effective than noble-metal catalysts, demonstrating excellent performance in enhancing the thermal processes.
... These calculations are based on operational parameters specific to the propellant combination and on the mission scenario. In terms of feeding architectures, four possibilities are implemented: blow-down, pressure-fed, electric pump fed [22] and self-pressurizing. Naturally, certain propellant combinations are only compatible with certain types of feeding systems. ...
This paper presents a comprehensive framework for designing in-space propulsion systems, integrating four criteria: global propulsive performance, environmental impact, cost efficiency, and architectural reliability. The study focuses on the emerging class of Orbital Transfer Vehicles to illustrate the application of this method. By examining the synergistic potential of OTVs and greener propellants, the paper addresses different mission scenarios, including LEO, GEO, and lunar missions, with both scientific and commercial objectives. The proposed framework aims to go beyond traditional cost-centric approaches, offering a more complete evaluation method for early design phases. A case study comparing three liquid bipropellant options, pressure-fed MON-3/MMH, 98%-HTP/RP-1, and self-pressurizing N2O/Ethane, demonstrates the utility of the tool. Findings suggest that scientific missions benefit most from 98%-HTP/RP-1, while traditional propellants remain preferable for cost-driven commercial missions to GEO and the MOON, though greener alternatives are competitive for less demanding LEO missions. This innovative framework aims to guide the selection of propulsion systems to achieve greener space missions, aligning traditional performance figures with environmental responsibility.
... It is important to note that MMH, a derivative of Hydrazine, has a higher environmental impact than Hydrazine itself. However, it is worth mentioning that MMH and UDMH (another Hydrazine derivative used in space applications) are not currently targeted by the REACH regulation [7]. Figure III.8) undergo a reliability assessment to see if they are able to satisfy the reliability requirement, set to 0.99 after 1 year of operation. ...
Aligning with the current shift towards greener energy, many space companies are already replacing toxic rocket fuels with greener ones. However, this often implies taking risk in a domain that is rather risk adverse. To help into taking this leap, the tool presented here gives a quick analysis of the different propulsion options able to fulfil certain types of in-space missions. Kick stages are taken as reference system for their prospects in facilitating mission logistics and their abilities to fulfill a wide range of missions. Taking as inputs mission scenarios parameters, the tool evaluates the propulsive options with respect to four figures of merit: propulsive performance, environmental performance, reliability and cost effectiveness. To illustrate the functioning of the tool, five propulsive options with different propellant combinations and feeding architectures are evaluated over three mission scenarios to LEO, GEO and MOON orbits. A final trade-off and system selection reveals that the most suitable propulsion choices vary depending on whether the mission is meant for scientific or commercial purposes.
... However, the low maturity of the technology leads to significant uncertainties that need to be properly studied before ultimately confirming the appeal of the green-propellant and e-pumps duo. Due to this, a one-factor-at-a-time (OFAT) sensitivity analysis was already performed in Ref. [13]. The present paper seeks to complement and expand this work by presenting a more refined, global sensitivity analysis to investigate the influence of the input parameters set in the final mass of the system and the robustness of the proposed approach. ...
... Being extremely carcinogenic, the European Chemical Agency (ECHA) has labelled hydrazine and NTO according to the Global Harmonized System (GHS). Using the 1:5 scale provided by GHS, hydrazine would rate a value of 3, being the first category the most toxic one [13]. Figure 3 identifies the hazard classification and labelling for each substance. ...
... • A 400 N HTP/Ethanol engine [12] • A 500 HTP/Propane engine [13] • An FLPP LunaNova HTP/Kerosene e-pump engine [11] The applied mathematical model calculates the component masses for both, the electric pump-fed and the pressurefed version, based on a given set of input parameters, including operational and system design ones. Then, it compares the results and assesses the convenience of one or the other pressurisation method for the selected study case. ...
... The same pressure-fed solution has been adopted also for the N 2 O powered Perun sounding rocket [22]. Electric pump feeding is currently being investigated, but N 2 O is prone to flashing and cavitation, making it critical for a pump-fed systems [54]. ...
The exploitation of Hybrid Rocket Engines (HREs) for future space transportation systems is currently being investigated in the framework of the ASCenSIon project, where Université Libre de Bruxelles (ULB) provides expertise in the field of design and experimental investigation of HREs. In particular, the Aero-Thermo-Mechanics (ATM) department of ULB features a 1kN test bench for ballistics and performance investigation and an optical access hybrid rocket slab burner to analyze the oxidizer-fuel interaction at the burning surface of the fuel grains. This know-how enables ATM to pursue and validate the sounding rocket development. In this work, a scalability investigation of the N2O/Paraffin HRE technology to the propulsion system of an experimental sounding rocket for microgravity research has been carried out. After the definition of the requirements by comparison with existing sounding rockets, a discussion of the design rationale is presented. Then, a deeper analysis with focus on the propulsion systems properties and trade-offs on materials and operative conditions is carried out, in order to infer the weight of the system and estimate the final performance of the engine. This scalability and feasibility study on conceptual level marks the first step towards the experimental investigation of the propulsive system and will help to pursue the goal of a ULB hybrid sounding rocket.
... In those bipropellant engines, it is indeed the most commonly researched oxidizer, being the only compound presenting moderate performance and good "green" properties. The other common oxidizer is Nitrous Oxide for selfpressurizing systems that shows lower performances but different advantageous properties [20]. LunaNova foresees the implementation of a pressurisation system to boost performances, hence Hydrogen Peroxide is preferred. ...
The fast-paced growth of the space sector brings in new challenges especially with upcoming complex missions combining multi-orbit deliveries and/or on-orbit servicing such as Active Debris Removal (ADR). Europe has taken up the challenges and is working on extending its launchers portfolio and capabilities. In this framework, a new add-on, the kick stage, confers strategic advantages to the launcher in expanding its missions' range. While many kick stages are currently developed, or already in use worldwide, this paper pays a particular attention to the new ASTRIS kick stage developed and optimized for A6 and its next kick stage generation already under conceptual study, LunaNova, at ArianeGroup Bremen for A6 Evolution. The project takes place under the ESA Future Launchers Preparatory Programme (FLPP) and is already implementing new technologies, namely innovative pressurization system and green propellants which are of special interest here. The paper starts by introducing the kick stage capabilities, especially the LunaNova ones, to then focus on the cost-oriented trade-off performed to select the fuel to use in combination with 98%-HTP to power the LunaNova vehicle. The paper then concludes by discussing the system impacts of implementing green propellants within the operational kick stage life cycle and its possible enhancement (namely the implementation of an e-pump).
... Indeed, a preliminary study of GP & e-pump versus pressure-fed toxic propellant option for a kick stage [46] showed an increase in specific impulse while keeping the system mass constant. For what concerns the use of HREs in the private space transportation sector, several start-ups are developing their own small launcher using this propulsion system, as was shown in Table 2. ...
The growing demand for cheaper space access calls for a more economically and environmentally sustainable approach for launchers. Concurrently, the shift to smaller satellites and the rise of constellations necessitate launchers capable of precise multi-payload/multi-orbit injection. ASCenSIon (Advancing Space Access Capabilities-Reusability and Multiple Satellite Injection), a Marie Skłodowska-Curie Innovative Training Network funded by Horizon 2020 (H2020), aims to respond to these demands. This paper describes the activities explored within ASCenSIon dedicated to developing novel green upper stages with multi-payload/multi-orbit injection capability. The aspects investigated here include the general system architecture, innovative solutions for the propulsion system (e.g., Hybrid Rocket Engines (HREs), green propellants and electric pump feeding), Guidance Navigation and Control (GNC) solutions for the multi-payload/multi-orbit injection capability, and reliability aspects of upper stages. First, relevant space market considerations are raised. Then, solutions for more environmentally friendly propulsion systems are proposed. Since identifying a good substitute for toxic hydrazine recently became a priority, the use of green propellant technologies will be assessed, tackling specific problems such as benchmarked propulsive performances, storability and material compatibility. Another promising solution for future propulsion systems with lower environmental impact are HREs. They bring benefits in terms of flexibility, safety and cost. However, high residual mass, oxidizer-to-fuel ratio (O/F) shift during operation, low regression rate and combustion inefficiency are some of the challenges that still need to be addressed in their application. In addition, electric pump fed systems, powered by green propellants, may be a game-changer technology for future upper stages. Compared to pressure-fed, it can provide improved performance and lower inert mass. With respect to turbopumps, it may also be advantageous in terms of simplicity and costs. On the other hand, battery mass and thermal control represent some of the drawbacks to overcome. Additionally, the implementation of novel GNC solutions is critical to ensure the multi-payload/multi-orbit injection capability. The challenges brought by the design of such a system are presented, including the correlation with the overall upper stage definition. Finally, the reliability of the launchers is a key aspect to protect both the space environment and the safety of the missions. Novel methods for reliability modelling of launchers are discussed and advantageous system architectures are proposed. These novel technologies being jointly assessed, this paper presents a preliminary analysis of the discussed topics and their interconnections within ASCenSIon, aiming at satisfying new requirements for novel green upper stages.
