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VEGA launch vehicle upper stage re-entry survivability analysis
Abstract
A key task in launch vehicle (LV) system design process consists in the estimation of upper stage fragmentation during atmospheric re-entry once accomplished the launcher mission, and the related probability of making on-ground casualties. According to international policy for space debris mitigation, VEGA upper stage AVUM re-entry from its final orbit is analyzed by means of numerical tools, in order to identify which objects are demised during atmospheric re-entry and which ones are able to withstand aerothermal loads impacting on ground. The logic is based on parent/child concept: initially the S/C is modelled as one parent object. The parent object virtually contains all other internal components of the S/C. The output of the analysis comprises the mass, cross-section, velocity, incident angle of the surviving fragments and their casualty area. Final casualty risk assessment is then performed starting from the survivability analysis results achieved and compared to applicable regulations. Application on Vega LV maiden flight provide practical results.
... The Vega AVUM is the Attitude and Vernier Upper Module of the Vega rocket, an expendable launch system developed by the European Space Agency (ESA) and the Italian Space Agency [54]. It is used to provide additional propulsion and guidance for the Vega rocket during its ascent to orbit. ...
... The AVUM upper stage consists of several components with different materials, retrieved from ESTIMATE library [29]; for more information on the components and their materials, please refer to [54,56]. The geometrical model used in this study was built to mimic the connections among the various components of the AVUM and simulate their fragmentation via thermal dissolution triggers, which are activated when a given "demisable joint" in the assembly reaches a predefined temperature. ...
The aerothermodynamic environment surrounding bodies undergoing destructive atmospheric entry is characterized by multiple interacting shock waves generated by the presence of several fragments moving close to one another at high speed. Shock interaction and impingement produce highly localized surface loads, influencing the overall dynamics of the fragment, its temperature, and in turn its demise. To account for the relevant physics during the reentry process of fragmenting bodies, a multifidelity framework is presented that allows for selecting the most appropriate level of fidelity, between high-fidelity solutions or low-fidelity aerothermodynamic metamodels. A physics-informed approach is implemented to automatically choose between the two fidelity levels on the basis of the intersection of shock wave envelopes. The complete framework is validated on relevant test cases from the literature and its performance is demonstrated for destructive atmospheric reentry cases, such as the case of the Attitude Vernier Upper Module and the Automated Transfer Vehicle from the European Space Agency.
... Therefore, object-oriented codes are not able to fully describe the spacecraft structure but provide a conservative analysis at a much lower computational cost. Examples of object-oriented codes are NASA's DAS and ORSAT, and ESA's DRAMA, which are routinely used to verify the compliance of space missions with the ground safety requirements (Battie et al., 2012, Rochelle et al., 2004. ...
... Following this consideration, spacecraft tanks were selected as reference components. In fact, they are sensitive components for the demisability as they usually survive reentry (National Astronautics and Space Administration, 1997, National Astronautics and Space Administration, 2001, Battie et al., 2012. At the same time, it is important to ensure adequate protection and resistance of tanks from debris impact as, being pressurised, they are particularly susceptible to ruptures and leakage (Putzar and Schäfer, 2006). ...
In the past two decades, the attention towards a more sustainable use of outer space has increased steadily. The major space-faring nations and international committees have proposed a series of debris mitigation measures to ensure the sustainability of the space environment. Among these mitigation measures, the de-orbiting of spacecraft at the end of their operational life is recommended in order to reduce the risk of collisions in orbit. However, re-entering spacecraft can pose a risk to people and property on the ground. A possible way to limit this risk is to use a design-for-demise philosophy, where the spacecraft is designed such that most of its components will not survive the re-entry process. However, a spacecraft designed for demise still must survive the space environment for many years. As a large number of space debris populates the space around the Earth, a spacecraft can suffer impacts from these particles, which can be extremely dangerous. This means that the spacecraft design has also to comply with the requirements arising from the survivability against debris impacts. The demisability and survivability of a spacecraft are both influenced by a set of common design drivers, such as the material of the structure, its shape, dimension, and position inside the spacecraft. It is important to consider such design choices and how they influence the mission’s survivability and demisability from the early stages of the mission design process. The thesis addresses these points with an increasingly higher level of detail by a continuous and interlinked development of a demisability and a survivability model, of two criteria to evaluate the level of demisability and survivability, and of a common framework where both models communicate and interact to find optimal solutions. First, the initial versions of the models, which is limited to simple geometrical shapes, uniform materials, and dimensions, is used to study the sensitivity of the demisability and of the survivability indices as a function of typical design-for-demise options. As new features are introduced, such as the capability of considering internal components and sub-component together with their position inside the spacecraft, as well as the type of shielding, also the analyses become more detailed. As the demisability and the survivability of a spacecraft configuration are closely linked, it is important to assess them in a concurrent fashion for which a multi-objective optimisation framework has been developed. Here the survivability and the
demisability requirements are considered simultaneously and trade-off solutions of spacecraft configurations can be obtained. The final part of the thesis presents a test case for the application of the framework, targeting one of the most interesting components from both a demisability and a survivability standpoint that are tank assemblies. Finally, a preliminary study concerning the development of a new demisability index is presented.
... Following this consideration, we decided to select a tank as reference component. Tanks are in fact sensitive components for the demisability as they usually survive re-entry [53][54][55]. At the same time, it is important to ensure adequate protection and resistance of tanks from debris impact as, being pressurised, they are particularly susceptible to ruptures and leakage [39]. ...
The paper is concerned with examining the effects that design-for-demise solutions can have not only on the demisability of components, but also on their survivability that is their capability to withstand impacts from space debris. First two models are introduced. A demisability model to predict the behaviour of spacecraft components during the atmospheric re-entry and a survivability model to assess the vulnerability of spacecraft structures against space debris impacts. Two indices that evaluate the level of demisability and survivability are also proposed. The two models are then used to study the sensitivity of the demisability and of the survivability indices as a function of typical design-for-demise options. The demisability and the survivability can in fact be influenced by the same design parameters in a competing fashion that is while the demisability is improved, the survivability is worsened and vice versa. The analysis shows how the design-for-demise solutions influence the demisability and the survivability independently. In addition, the effect that a solution has simultaneously on the two criteria is assessed. Results shows which, among the design-for-demise parameters mostly influence the demisability and the survivability. For such design parameters maps are presented, describing their influence on the demisability and survivability indices. These maps represent a useful tool to quickly assess the level of demisability and survivability that can be expected from a component, when specific design parameters are changed.
... Following this consideration, we decided to select a tank as reference component. Tanks are in fact sensitive components for the demisability as they usually survive re-entry [53][54][55]. At the same time, it is important to ensure adequate protection and resistance of tanks from debris impact as, being pressurised, they are particularly susceptible to ruptures and leakage [39]. ...
The paper is concerned with examining the effects that design-for-demise solutions can have not only on the demisability of components, but also on their survivability that is their capability to withstand impacts from space debris. First two models are introduced. A demisability model to predict the behaviour of spacecraft components during the atmospheric re-entry and a survivability model to assess the vulnerability of spacecraft structures against space debris impacts. Two indices that evaluate the level of demisability and survivability are also proposed. The two models are then used to study the sensitivity of the demisability and of the survivability indices as a function of typical design-for-demise options. The demisability and the survivability can in fact be influenced by the same design parameters in a competing fashion that is while the demisability is improved, the survivability is worsened and vice versa. The analysis shows how the design-for-demise solutions influence the demisability and the survivability independently. In addition, the effect that a solution has simultaneously on the two criteria is assessed. Results shows which, among the design-for-demise parameters mostly influence the demisability and the survivability. For such design parameters maps are presented, describing their influence on the demisability and survivability indices. These maps represent a useful tool to quickly assess the level of demisability and survivability that can be expected from a component, when specific design parameters are changed.
... Figure 1.8 shows the area in which debris generally spread after breakups. Most of the breakups occur at ∼ 80 km [Battie et al., 2012] [Ailor, 2012] so it is impossible to predict the size and the ballistic coefficient of each fragment in advance. An a priori value of the ballistic coefficient given to an estimator may, therefore, have high errors. ...
Space debris tracking during atmospheric re-entries will be a crucial challenge in the coming years,
emphasized through many projects on space debris mitigation established by space agencies
worldwide. However, this problem appears to be complex, due to model errors and difficulties to
properly initialize the estimation algorithms, as a result of unknown dynamics of the debris and their
disintegrations during the re-entries. A-to-be used estimator for this problem must be robust against
these factors. The Moving Horizon Estimator (MHE) is known in the literature to be robust to model
errors and bad initialization, and the PhD work has proved its ability to satisfy performances required
by the debris tracking during the re-entries. However, its optimization-based framework induces a
large computation time. To overcome this, a new MHE structure which requires smaller computation
time than the classical MHE has been developed. This strategy, so-called “Moving Horizon Estimator
with Pre-Estimation (MHE-PE)” takes into account model errors by using an auxiliary estimator rather
than by searching for estimates of the process noise sequence over the horizon as in the classical
strategy. A theorem which guarantees the stability of the dynamics of the estimation errors of the
MHE-PE has also been proposed. Finally, performances of this structure in the context of 3D space
debris tracking during the re-entries have been shown to be better than those obtained with classical
estimators including the MHE. In particular, without degrading accuracy of the estimates and
convergence of the estimator, the MHE-PE estimator requires smaller computation time than the
MHE thanks to its small number of optimization variables.
... Figure 1.8 shows the area in which debris generally spread after breakups. Most of the breakups occur at ∼ 80 km [Battie et al., 2012] [Ailor, 2012] so it is impossible to predict the size and the ballistic coefficient of each fragment in advance. An a priori value of the ballistic coefficient given to an estimator may, therefore, have high errors. ...
Space debris tracking during atmospheric re-entries will be a crucial challenge in the coming years, emphasized through many projects on space debris mitigation established by space agencies worldwide. However, this problem appears to be complex, due to model errors and difficulties to properly initialize the estimation algorithms, as a result of unknown dynamics of the debris and their disintegrations during the re-entries. A-to-be used estimator for this problem must be robust against these factors. The Moving Horizon Estimator (MHE) is known in the literature to be robust to model errors and bad initialization, and the PhD work has proved its ability to satisfy performances required by the debris tracking during the re-entries. However, its optimization-based framework induces a large computation time. To overcome this, a new MHE structure which requires smaller computation time than the classical MHE has been developed. This strategy, so-called “Moving Horizon Estimator with Pre-Estimation (MHE-PE)” takes into account model errors by using an auxiliary estimator rather than by searching for estimates of the process noise sequence over the horizon as in the classical strategy. A theorem which guarantees the stability of the dynamics of the estimation errors of the MHE-PE has also been proposed. Finally, performances of this structure in the context of 3D space debris tracking during the re-entries have been shown to be better than those obtained with classical estimators including the MHE. In particular, without degrading accuracy of the estimates and convergence of the estimator, the MHE-PE estimator requires smaller computation time than the MHE thanks to its small number of optimization variables.
The ever-increasing number of man-made space debris creates the need for new technologies to mitigate it. Therefore, within the ESA-funded project BIOINSPACED, biologically inspired solutions for active debris removal were investigated, conceptualized and integrated to innovative and comprehensive scenarios. In the following, the collection process of existing and new biomimetic concepts as well as the evaluation of ten concepts based on a feasibility analysis will be presented. Out of the ten, the three most promising scenarios, were chosen for further investigation and further elaborated in detail specifying the biological models incorporated as well as how the scenario could be implemented in a simple demonstrator. The first scenario (A) is a gecko kit canon and describes a system that fires deorbiting kits towards the target from a safe distance. The second scenario (B) involves a robotic arm with a gecko-adhesive end-effector and a bee-inspired harpoon to achieve a preliminary and subsequent rigid connection to the target. The last scenario (C) is mimicking a Venus Flytrap and its bi-stale mechanism to capture its prey. One of these scenarios will be manufactured and built into a demonstrator to showcase biology's potential for the development, optimization and improvement of technologies, especially within the space industry.
Koppenwallner Debris Risk Assessment and Mitigation Analysis (DRAMA) Tool Final Report
- C Martin
- J Cheese
- N Sanchez
- K Ortiz
- H Bunte
- T Klinkrad
- B Lips
- G Fritsche
Debris Risk Assessment and Mitigation Analysis (DRAMA) Tool Final Report, QinetiQ, DEIMOS Space, eta_max space, ESA/ESOC, HTG
- C Martin
- J Cheese
- N Sanchez Ortiz
- K Bunte
- H Klinkrad
- T Lips
- B Fritsche
- G Koppenwallner