Technische Universität Dresden
Institut für Luft- und Raumfahrt
Christian Bach
Marschnerstr. 32
01307 Dresden

Phone: +49 (351) 463-38097
Fax: +49 (351) 463-38125
http://ascension-itn.eu

Individual Research Projects (IRPs)

ESR1 - Health Monitoring of RLV components (WP2, WP4)

  • Host institution:
    Technische Universität Dresden
  • Main Supervisor:
    Dr. Tino Schmiel
  • Enrolment:
    Technische Universität Dresden

The research focus of ESR1 is on technologies for Reusable Launch Vehicles (RLVs), more specifically on health management. Evaluating the health status of a vehicle is fundamental for promoting its re-usability.
Covering the role of ESR1 at Technische Universität Dresden, the research activities are divided in three sections consisting in the analysis of critical points for RLVs in terms of sensing parameters; evaluation and preliminary selection of sensors for covering the technological gaps; investigation of integration strategies with related sensing and processing architecture decomposition; investigation of algorithms for health estimation focusing on anomaly detection and prognosis. The algorithmic analysis is divided into signal processing methods and Machine Learning (ML) approaches.
The final goals of the research activities are the evaluation of sensing and processing procedures for health status estimation as well as of algorithms for anomaly detection and state prediction.

ESR2 - RLV recovery strategies (WP2, WP4)

  • Host institution:
    Technische Universität Dresden
  • Main Supervisor:
    Dr. Christian Bach
  • Enrolment:
    Technische Universität Dresden

The research focus of ESR 2 is on technologies for Reusable Launch Vehicles recovery, more specifically on retro-propulsion in vertical landing scenarios. In this field, Advanced Nozzle Concepts (such as Aerospike Engines and Dual-bell Nozzles) could overcome critical phenomena that arise during atmospheric re-entry and retro-propulsion maneuvers, together with achieving performance gains during ascent/boost-back/descent phases thanks to their intrinsic altitude-compensation and higher expansion ratios.

In role of ESR 2 at Technische Universität Dresden, the research activities include design and 3D printing of advanced nozzles in collaboration with ESR 6, cold-flow experimental campaigns on conventional and advanced nozzles in various retro-flow configurations, together with ground-effect investigations. These activities include performance evaluation at design points and sea-level condition, optical diagnostic techniques (i.e., background-oriented schlieren) and measurements of pressure distribution along a reference body-extension for evaluation of pressure coefficients for the aerodynamics resulting from counter-flow/nozzle-jet interaction. The experiments are supported in parallel by numerical studies in AnSYS Fluent as visualization tools of the aerodynamics interference between the flows, evaluation of aerodynamic coefficients and extension of this study to uniform counter-flows that could not be replicated though experiments.

The final goals of the research activities include the generation of a numerical and experimental database for retro engines with reverse-flow interactions, together with the justification of the choice of a favorable engine layout for retro-propulsion applications.

ESR3 - System aspects of RLV (WP2 – WP4)

  • Host institution:
    German Aerospace Center
  • Main Supervisor:
    Dr. Martin Sippel
  • Enrolment:
    Universität Bremen

The topic of this research involves the understanding and mastering of the reusable launcher design process by surveying and advancing the current scientific knowledge in how computational resources can merge with engineering intellect and judgement for the efficient design of reusable space systems. Particularly, it synthesized a fast conceptual methodology for performing architectures trade offs of various RLV options, as shown in Figure 1, and explored the role of Multi-Disciplinary Design Optimization (MDAO) and the interaction with the various engineering disciplines (Figure 2), attempting to enhance their fidelity for early design stages, where it is easy to make specific changes and improve the vehicle design. Within disciplinary roles, it focuses on structural design, which is lagging in the application of current state of art MDAO studies (Figure 3), and in branching trajectory optimization within MDO (Figure 4), a necessary step for the successful design of RLVs. In addition, the research further explores and advances the rather new field of the environmental sustainability of launchers, to understand the main drivers from a system perspective, and devise mitigation approaches, as adapting oxidizer to fuel ratios or even launch and reentry profiles (Figure 5). In addition, it also assesses uncertainty implications and its inclusion in the robust and reliable vehicle design, with a particular focus on the uncertainty in vehicle lifecycle assessments. This allows to reduce design safety margins by direct quantification, avoiding over conservative designs which may result in artificially unfeasible concepts and applications. With these, important steps would be accomplished to eventually enable a truly robust design approach for ecologically and economically sustainable access to space.

ESR4 - Propulsion systems and their reusability (WP2)

  • Host institution:
    German Aerospace Center
  • Main Supervisor:
    Prof. Michael Oschwald
  • Enrolment: Rheinisch-Westfälische Technische Hochschule Aachen

Mateusz’s area of activity enfolds rocket engine design and operation with a specific focus on methods for fatigue life estimation of highly loaded rocket engine components into low order tools for rocket engine cycle modeling. A development of reusable launch system is crucial for lowering the costs of access to space, hence making it possible for a commercial future space traveling in a similar manner as aircraft journey. With engine operation life in excess of a single mission, it is necessary to evaluate the most critical components, such as turbopumps or regeneratively cooled combustion chamber, experiencing exceptionally high load which considerably reduces their life. Mateusz’s study is therefore focused on the turbopump and combustion chamber analysis for reusable LRE applications in context of various engine cycle modelling. The long-term objective encompasses enhancement of damage simulation models with improved interplay between significant factors of elevated temperature, cyclic conditions and fatigue life mechanisms. These proposed methods are developed with various LRE’s architecture supported by a system level simulation (SLS) and implementation of propulsion modeling tools, such as EcosimPro ESPSS - European Space Propulsion Simulation Toolkit. As a result, a more accurate prediction models of the LREs components remaining useful life for a given engine configuration are developed.

ESR5 - Assessment of green propellants for reusable launchers (WP2 and WP3)

  • Host institution:
    Sitael
  • Main Supervisor:
    Dr. Giovanni Pace
  • Enrolment:
    Università di Pisa

Within the ASCenSIon project, I am working on green propulsion technologies for future launchers at Pisa University. Following the space sector current trends and needs, in search of cheaper and more efficient muti-orbit deliveries and in-space servicing, I am focusing on kick stage systems, also called orbital stages. This novel type of space vehicle, actively developed worldwide, presents the perfect opportunity for greener propellants to breakthrough as the whole system design is to be revisited from scratch. Indeed, while legacy toxic propellants are currently under the shadow of the REACH regulations, greener propellants are not yet widely used because of their own specific drawbacks to overcome requiring changeover at system and subsystem levels. For a kick stage powered by a liquid bipropellant combination, greener alternatives than the current one are either self-pressurized combinations with Nitrous Oxide as oxidizer (N2O) or combinations using High-Test-Peroxide (HTP) as oxidizer.

Together with my secondment at ArianeGroup Bremen these inputs kicked off the development of a tool, on which I am currently working, to evaluate orbital stage propulsion systems with respect to its given mission scenario. The tool will incorporate not only propulsive performance but will also look at cost and environmental efficiencies to provide a greener solution adapted for future missions.

ESR6 - Advanced Nozzle Concepts (ANCs) for reusable launchers (WP2 – WP4)

  • Host institution:
    Università di Roma La Sapienza
  • Main Supervisor:
    Prof. Daniele Bianchi
  • Enrolment:
    Università di Roma La Sapienza

In previous studies [1] it has been shown that the operational efficiency is one of the key demands of space transportation systems. In this context, performance losses caused by non-adaptation of the flow in the expansion process represent the largest loss source for conventional rocket nozzles, with losses up to 15%. The reason is that these nozzles can be adapted or optimally designed only for a single trajectory point along the entire ascent phase. In contrast, Advanced Nozzle Concepts (ANCs) such as, among others, expansion-deflection and plug/ aerospike nozzles are able to adapt to different altitudes. The latter concept adapts even theoretically up to its geometric expansion ratio. However, from experiments conducted in the 1960 by NASA under Wasko [2] it could be found out that the altitude adaptation of the ED nozzle is inferior to the Plug nozzle due to higher aspiration and overexpansion losses. This was the reason for relatively low interest on the ED nozzle concept for many years.  

However, according to Goetz and Hagemann [3] the applicability of ED nozzles seems to improve if they are just operated under vacuum condition where altitude adaptation does not matter anymore and the nozzle operates just under closed wake conditions. Similar to plug nozzles the ED nozzles could be designed much shorter (thus lower weight) than conventional nozzles maintaining the same specific impulse (Isp). This higher Isp/ W ratio could be used for increasing the payload and making the space access cheaper. In addition, there is another advantage of the ED nozzle. In general, Plug nozzles suffer its biggest drawback of very tiny throat gaps and thus wall heat fluxes due to relatively high radial throat distance from the symmetry axis. ED nozzles can in general be designed with bigger throat gaps than Plug nozzles maintaining the same throat area since the throat is located closer to the symmetry axis. This at the end means that the ED nozzle could combine both advantages of higher Isp/W ratio by keeping the wall heat fluxes relatively low.  

Due to these reasons within this individual research project (IRP) ED nozzles are designed and analyzed in terms of performance and heat fluxes and since the best ANC is very closely related to the architecture and mission constraints of the overall launcher also systems aspects.

[1] T. V. Nguyen, G. E. Dumnov, G. Hagemann and H. Immich. Advanced rocket nozzles. Journal of Propulsion and Power, 14(5):620-634, September 1998

[2] Robert A. Wasko. PERFORMANCE OF ANNULAR PLUG AND EXPANSION-DEFLECTION NOZZLES INCLUDING EXTERNAL FLOW EFFECTS AT TRANSONIC MACH NUMBERS. NASA April 1968

[3] A. Goetz and G. Hagemann et. Al. Advanced Upper Stage Propulsion Concept – The Expansion Deflection Upper Stage. Stage; Conference: 41st AIAA/ASME/SAE/ASEE Joint Propulsion Conference Exhibit. July 2005; DOI:10.2514/6.2005-3752

ESR7 - Numerical and analytical ATD modelling for reusable launchers (WP2 and WP4)

  • Host institution:
    ONERA
  • Main Supervisor:
    Dr. François Chedevergne
  • Enrolment:
    ISAE-SUPAERO

The research for the PhD project on “Aerothermodynamic Modelling for Reusable Launchers” focuses on developing a surrogate model to predict the wall heat flux for multiple trajectories and different vehicle designs using a database of CFD (Computational Fluid Dynamics) calculations. The research is conducted mainly at the French Aerospace Lab (ONERA) in Toulouse. The surrogate model aims to provide a prediction with a low response time and sufficient accuracy for pre-design purposes in the development of reusable launch vehicles in collaboration with GNC optimization and system design aspects.

The development of such a model is separated in three main steps: the creation of a database, the preprocessing of the data and the development and validation of the surrogate model. CFD Navier-Stokes calculations with the in-house code CEDRE are performed for laminar continuum hypersonic flows regimes. In order to reproduce the physical properties during the flight, the calculations are made for a flow in chemical non-equilibrium based on the Park’s kinetics model (5 species, 17 reactions) and under the assumption of thermal equilibrium and a super catalytic wall. However, from a chemical point of view, the gas condition is not fixed by the user but by the local flow conditions. Therefore, the flow can be locally a perfect gas or real gas at thermochemical equilibrium or chemical non-equilibrium state. The heat flux was determined for either radiative equilibrium or under a fixed wall temperature condition.

The preprocessing includes different filtering processes and the transformation to non-dimensional variables to permit the combination of CFD data obtained at different flight points. This required the development of a sperate 1D- model predicting the nose heat flux based on the flight environment of the vehicle. At last, the development of the surrogate model consists of establishing and validating a model using machine learning techniques such as Kriging or Neural Networks. The prediction of the surface heat flux is then made based on the information of the pressure and pressure gradient on the surface.

ESR8 - Design of an upper stage HRE for orbital deployment of various payloads in various orbits (WP3)

  • Host institution:
    ONERA
  • Main Supervisor:
    Dr. Jouke Hijlkema
  • Enrolment:
    ISAE-SUPAERO

The overall goal for my PhD is to design a Hybrid Rocket Engine (HRE) for an upper stage application. An HRE is basically a cylinder of plastic (or paraffin wax) connected to an oxidizer (e.g., hydrogen peroxide, nitrous oxide) on one side and a nozzle on the other side. Of course, this is an oversimplification but it gives a good idea of how much less complex hybrids are when compared to liquid engines. Nonetheless, HREs suffer from low fuel regression rates. This means that the solid fuel (plastic) burns relatively slow (around 10 times slower than a solid rocket), and this low mass flow translates directly to lower thrust. So usually, in HREs, we need to either increase the burning surface to augment the mass flow (which makes the volumetric loading rather bad) or find some techniques to increase the regression rate.

That is where my research comes into play. I am researching ways to improve this low regression rate by increasing the mixing and turbulence inside the combustion chamber. The core of my ideas lies in the use of steps. Just imagine you are sitting in a bathtub with cold water and you have only a small stream of hot water to increase the temperature. If you start mixing the water with your hands, the heat will be transported faster. With a bit of a stretch, this is what the steps in HREs do: they introduce recirculation zones that increase the heat transfer. On top, we can use these steps to approximate all kinds of different geometries inside the fuel port to have positive side effects like mixing ratios that are closer to stoichiometry. In the picture, you can see two representative fuel grains that are composed of different segments with different inner diameters. When assembled, the fuel block consists of a stepped profile. With these stepped profiles/designs, at the end, we will be able to design upper stage HREs that fit their Use-case the best.

ESR9 - Experimental study of HRE with regression rate measurements (WP3)

  • Host institution:
    Université libre de Bruxelles
  • Main Supervisor:
    Prof. Patrick Hendrick
  • Enrolment:
    Université libre de Bruxelles

I am working for the ASCenSIon project at Université Libre de Bruxelles, where I focus on the experimental investigation of the internal ballistics of hybrid rocket engines, suitable for advanced upper stage applications.

The focus of my research is to understand what happens inside the combustion chamber when the engine is burning, and for this purpose I designed a hybrid rocket slab burner, where fuel samples can react with a flow of gaseous oxygen at different pressures and mass flow rates, and two quartz glass windows can be used to visualize the flame and collect data on the combustion using a high-speed camera. The burner has also been used to evaluate the performance of different fuels in small-scale, before moving to a commercial-scale engine.

Together with the rocket propulsion group of the Aero-Thermo-Mechanics department, I then provided ASCenSIon with a database of performance characteristics and regression rate of different paraffin-based fuels in combination with nanoparticles and metallic additives, acquired using a 1kN-thrust engine with nitrous oxide as oxidizer.

ESR10 - Feasibility demonstration of electric pump feeding (WP2, WP3)

  • Host institution:
    Hochschule Bremen
  • Main Supervisor:
    Prof. Uwe Apel
  • Enrolment:
    Technische Universität Dresden

In the last years, the space sector has faced a revolution in terms of sustainability and costs. From one side, "green" awareness has promoted the interest in new compounds that can be safer, less toxic, and ultimately reduce the operational costs related to hazardous propellants handling. New combinations have been proposed in this context, but the perfect substitute is still a holy grail.

On the other side, the current effort of the industry to standardise, mass-produce and verticalise the sector is undoubtedly an important constraint for turbopumps since they constitute one of the most critical and complex components of the whole propulsion system.

Moreover, this new vision is also calling for novel and improved mission profiles, which typically include satellite multiple injection capabilities. These maneuvres are essential, among other things, for efficient constellation deployment. Indeed, its importance is well acknowledged within the ASCenSIon project (ASCenSIon- Advancing Space Capabilities – Reusability and Multiple Satellite Injection).

What electric pump feeding can offer in these regards is

- To contribute to sustainability by leveraging green propellants' performance

- To simplify and decrease costs by reducing the number of components when compared to turbopumps

- To increase the performance when compared to pressure-fed

- To improve the system's multiple injection capabilities by simplifying the ignition sequence

In conclusion, new space is calling for a new vision in terms of performance, sustainability and costs. This PhD seeks to embrace these trends by assessing the feasibility of electric pump feeding in low to medium thrust applications together with the use of green propellants, particularly highly concentrated hydrogen peroxide. If competitiveness with respect to the traditional solution is demonstrated, i.e., a pressured fed system powered by hydrazine and nitrogen tetroxide, this fact could promote the change to a greener alternative within the thrust range of interest.

Within ASCenSIon, this individual research project is mainly comprised within WP3: Upper stages for multiple payload injection. Hence, the research is focused on the applicability of the technology for upper/kick stages. This fact imposes particular requirements and constraints which will be dealt with during the execution of the different project tasks.

ESR11 - Design solutions for green expendable upper stages (WP3, WP4)

  • Host institution:
    Università di Pisa
  • Main Supervisor:
    Prof. Angelo Pasini
  • Enrolment:
    Università di Pisa

I am Alberto Sarritzu, ESR11 of the Project ASCenSIon.

The focus of my research is the study and development of green propulsion technologies for multi-purpose orbital stages, also known as kick-stages.

The initial part of my study covered an extended analysis of the many “green” technologies to understand the most valuable alternatives, their advancements, and their applications to current systems. During this analysis I identified the most promising technologies that are currently studied in many research centres and that are the most likely to advance to real applications very soon.

The reference system, the kick-stage, covered an equal importance in the research. This class of systems is being developed by many private and public entities around the world and will cover a crucial role in the next future when the in-orbit servicing will become an everyday reality.

After the initial system-level studies, I focused on the most promising technologies identified and I worked on the development of key components like the injectors.

In particular, I worked on both liquid hypergolic combinations and self-pressurizing compounds, doubtlessly the two most promising branches of green propulsion.

During one secondment I worked with the German Aerospace Agency, DLR, on the development of new injectors for a hypergolic green combination developed by their laboratories in Lampoldshausen, taking part to both the design of new components and the following experimental campaign. During the other secondment, I worked on the self-pressurizing compounds analysis at a company that utilizes them in their systems, D-Orbit.

ESR12 - Reliability and safe disposal (WP3, WP4)

  • Host institution:
    Technische Universität Braunschweig
  • Main Supervisor:
    Prof. Enrico Stoll
  • Enrolment:
    Technische Universität Braunschweig

The launch rate has significantly increased over the past few years, and numerous launch vehicles are being developed to answer the growing demand for cheaper space access. As this tendency prevails, concerns related to the sustainability of activity in the space and Earth environments need to be addressed. These concerns drive the need to ensure the reliability of launch vehicles and the performance of a successful Post-Mission Disposal (PMD).

In the area of reliability, the work within this project has been focused on the development of a simplified reliability model of Liquid Rocket Engines (LREs), which were found to account for more than half of the launch failures that occurred since 2006. Traditional methods used to assess the reliability of launch vehicles are very time consuming and strongly rely on the expertise of the team performing the assessment. The goal of this model is to provide a quicker and easier to use alternative, in order to allow reliability-based decisions in early stages of the design. This method is not intended to substitute traditional methods, which are still required in later stages, but to complement them by providing early estimations based on a few key design parameters, which are reliability drivers.

In the area of the PMD, the work has been focused on the estimation of the orbital lifetime, in order to assess the compliance with the 25-years guideline established by the Inter-Agency Space Debris Coordination Committee (IADC) Space Debris Mitigation Guidelines. Analysis regarding the compliance by different launcher families, as well as the collision probability associated to each of them, have been performed. Moreover, the accuracy of the predictions with the commonly used tools has been assessed, by comparing real data with simulations. These analyses have been performed for rocket bodies both in Low Earth Orbit (LEO) and High Eccentric Orbits (HEO), and the different dynamics corresponding to each region have been analyzed. Finally, different approaches to improve the predictions in each orbital region are being studied, including better estimations of the ballistic coefficient and the use of probabilistic approaches for objects in HEO orbits.

ESR13 - GNC for launchers for multiple payload - multiple orbit delivery (WP2 – WP4)

  • Host institution:
    Politecnico di Milano
  • Main Supervisor:
    Prof. Michèle Lavagna
  • Enrolment:
    Politecnico di Milano

The recent years have shown a dramatic increase in the number of ongoing and planned launches, experimenting a growing tendency beyond the capabilities of current transport systems’ strategies. This situation, partially provoked by the participation of new players in the space sector as well as a shift of interest towards smaller sized satellites and constellation missions, demands of innovative solutions. Historically, a solution to this problem is to launch a bigger primary load, which drives the target orbit of injection, and a set of smaller secondary loads which depend on the former. This imposes several constraints in terms of flexibility for the non-primary loads, which in their turn require of higher fuel budget to manoeuvre towards their desired position. To counteract this cost and flexibility problem, a focus has been put on the design of an upper stage that can directly inject multiple satellites into their respective differentiated orbits. In particular, the research is focused on the definition of the reference to optimally reach the sequence of payloads, minimising both the total mission time and the fuel expenditure, which requires solving a complex problem involving both the sequence of visitation of orbits and the transfers between them.

For this purpose, a specific two-step optimization approach has been selected in which the first step selects the order of visitation and provides with a first guess for the transfers, which is then used by a more accurate Nonlinear Control Optimisation (NOC) algorithm to achieve the final optimal reference trajectory and the optimal control law associated to it.  The first step is computed by means of a two-layer bi-objective optimization algorithm which reduces the problem complexity by dividing the integer and continuous parts of the routing problem. In this manner, the outer loop solves the sequence problem using a Population-Based Ant Colony Optimization strategy. Each sequence is then evaluated inside the inner loop, which solves the optimization of the transfers given the order specified by the outer loop. The set of transfers is optimized by means of a Particle Swarm Optimization algorithm. The output of this step is a Pareto front of the optimal sequences, with the associated timestamped manoeuvres. Each one of these can then be used as a first guess for a multi-phase multi-shooting NOC method to achieve the full optimal control law and the optimal reference trajectory. In this more accurate solver, different effects of environmental disturbances can be implemented, as well as varying models for the different subsystems of the vehicle. In fact, it is to be used as well as a tool to perform a sensitivity analysis on the changes in the final trajectory due to alternative propulsion system designs or upper stage design choices.

The outcome of the research is then a flexible tool able to obtain the full trajectory and optimal control for the delivery of multiple payloads into differentiated orbits, allowing to include all the range of insertion conditions requests. It is also a tool which allows to perform a preliminary analysis on the mission definition for these multi-delivery scenarios, including the sensitivity analysis to different subsystems, contributing to the mission analysis efforts.

ESR14 - Optimal trajectories for reusable launchers re-entry (WP2, WP4)

  • Host institution:
    Politecnico di Milano
  • Main Supervisor:
    Prof. Michèle Lavagna
  • Enrolment:
    Politecnico di Milano

The controlled atmospheric re-entry associated with the precision soft-landing of Reusable Launch Vehicles (RLVs) on Earth is very challenging as it depends on multiple parameters. Over the last decade, the cost-effectiveness of such a technology has been finally demonstrated with the successful recoveries of SpaceX’s Falcon 9 first-stage rocket first, then followed by other companies such as the Rocket Lab’s Electron micro-launcher. This breakthrough has been made possible by the development of advanced and robust computational methods able to generate in real time the flight conditions and to command the optimal vehicle's deflections accordingly to achieve a safe pinpoint landing.

During an Earth atmospheric re-entry, the vehicle is subjected to fast system dynamics changes partly induced by external loads associated with the terrestrial environment (e.g., lift, drag, wind and gusts), but also by the actuation commands to answer the landing constraints satisfaction and the vehicle integrity preservation. All those involve uncertainties and nonlinearities, which lead to vehicle’s instability and therefore justify the implementation of a highly performant Guidance, Navigation and Control system. More particularly, one of the critical aspects is the design of a robust control strategy capable of counteracting the previously defined disturbances and uncertainties while satisfying the strict accuracy requirements associated with the pinpoint landing. This latter leads to another crucial requirement which is the real-time implementation of the guidance algorithm, generating the reference trajectory to be followed by the vehicle, and not trivial due to the high computational power needed to solve the highly nonlinear problem.

This IRP aims at developing a RLV re-entry dynamics simulator with closed-loop guidance and control integration, from design, to validation and critical discussion on some representative simulation cases. This simulator covers a vertical take-off vertical landing vehicle first-stage booster atmospheric re-entry and soft pinpoint landing. It includes the 6-Degree-of-Freedom (6-DoF) re-entry dynamics of a rigid-body model with varying mass, evolving in the terrestrial atmosphere with varying environmental parameters, uncertainties and disturbances (atmospheric density, ambient pressure, wind), and subjected to external forces (gravity, aerodynamics). To steer the spacecraft towards a controlled atmospheric re-entry and a soft pinpoint landing, the vehicle is equipped with a thrust vector control system, steerable planar fins and a reaction control system based on cold-gas thrusters. The objective of this simulator is to design and assess advanced and robust guidance and control methods, more particularly successive convex optimisation for the former; and the H-infinity family of methods for the latter. The addition of structural flexibilities and propellant sloshing dynamics effect, towards the implementation of a multi-body RLV model in the simulator, is also studied.

ESR15 - Mission analysis and GNC Missionisation for Re-entry Vehicles (WP4)

  • Host institution:
    Deimos Space
  • Main Supervisor:
    Mr. Davide Bonetti
  • Enrolment:
    Politecnico di Milano

ASCenSIon (Advancing Space Access Capabilities - Reusability and Multiple Satellite Injection) is born as an innovative training network with fifteen Early-Stage Researchers, ten beneficiaries, and fourteen partner organisations across Europe, to study the critical technologies for the development of the next generation of reusable space system. In this context, the objective of this research is the development of a Missionisation tool for re-entry vehicles. In recent years, leading space agencies and private companies are financing the development of reusable space vehicles to lower the costs of space access and in-orbit studies. The re-flight capability, required by the reusability of a space transportation system, prompts the necessity of a Mission Analysis (MA) and GNC missionisation process and tool for autonomous re-entry vehicles which reduces the tailoring efforts required for each mission. In literature there does not exist a clear definition of the word missionisation. The classical interpretation of missionisation is the recurrent activity to tailor the design of the solution for one particular mission. Within this research, however, the Mission Analysis (MA) and GNC missionisation of re-entry vehicles has a dual function. The first scope pursues the classical perspective, therefore addresses the tailoring and the updating of the mission analysis solution in terms of trajectory design with respect to the design parameters and the specific requirements of the mission itself. It applies to the last phases of the mission design and it aims at obtaining an optimal adaptation of the solution to the specific mission.  The second objective is the computation of common feasible design space domain for multiple missions. The goal, in this case, is the evaluation of the mission capabilities of an autonomous re-entry vehicle, in order to define the set of feasible missions that the vehicle is able to perform, as well as the performance maps with respect to the key design parameters. This objective concerns with the first phases of the mission design. The MA and GNC missionisation will play a crucial role in the reusability of a space vehicle, where multiple flights are addressed, indeed the final goal is the minimisation of the tailoring effort during the mission design phase by efficiently updating the MA and GNC solution and by obtaining already qualified solutions for a set of missions. The trajectory design, the evaluation of the performance and, in general, the design of the end-to-end mission of an autonomous re-entry vehicle by taking into account a wide set of mission and system requirements, is a multidisciplinary design analysis and optimization procedure. The development of a dedicated tool which includes all the disciplines to solve this problem is the main objective of this research. The first step to tackle this complex problem is to develop an MDA environment with proper mathematical models to assess the mission performance. The process, indeed, involves multiple disciplines, which allow for a numerical quantification of the related performance. Nonetheless, the identification of the disciplines is not sufficient, but a crucial step is the detection of the interactions (inputs and outputs) between them and the presence of loops. The inputs of a discipline, indeed, may be the output of another one. This operation is made by developing a proper Design Structure Matrix (DSM), which is a tool able to show in a single plot all the disciplines and all interactions among them. The second step implies the exploitation of MDO methodologies to build an MDO framework and, eventually, to solve the optimization problem. To address this aim, an introduction of both classical approaches, such as Multi-Objectives Particle Swarm Optimization and Sequential Quadratic Programming, and Metamodel-based techniques is given. The developed MDA environment, in fact, will be embedded in an optimization routine (MDO), in order to constitute a MA and GNC Missionisation tool for re-entry vehicles, which may have the potential of improving the efficiency and the quality of the tailoring and the design of the solutions. The tool, then, is validated with representative study case scenarios.

Funding and Coordination

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The project leading to this application has received funding from the European Union’s Horizon 2020 research and innovation programme under the Marie Skłodowska-Curie grant agreement No 860956.

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