Autonomous Formation Flight using Solar Radiation Pressure

Autonomous formation flight enables new satellite missions for novel applications. The cost and limits of propulsion systems can be overcome if environmental resources are being benefitted of. Currently, atmospheric drag is used in low Earth orbit to this end. Solar radiation pressure, which is of similar order of magnitude as aerodynamic ram pressure, is, however, always neglected. We introduce this force and show that it can be exploited. We demonstrate through simulations that a formation geometry is established quicker if the solar radiation pressure is modeled

Anomaly Detection Using Deep Learning Respecting the Resources on Board a CubeSat

peer reviewedWe explore the feasibility of onboard anomaly detection using artificial neural networks for CubeSat systems and related spacecraft where computing resources are limited. We gather data for training and evaluation using a CubeSat in a laboratory for a scenario where a malfunctioning component affects temperature fluctuations across the control system. This data, published in an open repository, guides the selection of suitable features, neural network architecture, and metrics comprising our anomaly detection algorithm. The precision and recall of the algorithm demonstrate improvements as compared to out-of-limit methods, whereas our open-source implementation for a typical microcontroller exhibits small memory overhead, and hence may coexist with existing control software without introducing new hardware. These features make our solution feasible to deploy on board a CubeSat, and thus on other, more advanced types of satellites

Autonomous Trustworthy Monitoring and Diagnosis of CubeSat Health (AtMonSat)

This document is the final report concluding the execution of the AtMonSat project co-funded by the European Space Agency (ESA) under the Open Space Innovation Platform (OSIP) and the University of Luxembourg. AtMonSat concerns on-board fault detection using artificial neural networks for CubeSat systems and related spacecraft where computing resources are limited. In particular, the concrete problem scenario of malfunctioning of CubeSat board elements is considered. The AtMonSat final report provides the problem statement, discusses the performed experiments designed to generate proper sets of data, and presents the details of the proposed solution. The report shows the devised framework to be both effective and suitable for implementation on a CubeSat

Blackout analysis of small cone-shaped reentry vehicles

The high temperatures associated with the hypersonic reentry process lead to an increase in the collisions between molecules, which may result in the disruption of the electronic structure, producing free electrons and ions. This production of free electrons and ions creates a plasma or ionized flowfield around the vehicle that is known to degrade the quality of radio-wave signal propagation, leading to a loss of communication or "blackout." This study involves performing hypersonic computational fluid dynamics simulations in the commercial software CFD++ with a bluntnosed cone geometry at different flight conditions to predict how and when ground communication can be achieved to aid in the design of an alert transmitter, which is an extension of aircraft collision-avoidance system technology. Computational results show that a small blunt-nosed cone geometry has decreased ionization regions as the cone angle decreases due to a shifting of the reaction zone further downstream. As a result, higher freestream velocities have less of an impact in determining the location for an antenna, and communicating along the stagnation line is seen to be independent of cone angle

3D Ray Tracing Solver for Communication Blackout Analysis in Atmospheric Entry Missions

During the atmospheric entry phase at hypersonic speed, the radio communication from/to a space vehicle can be disrupted due to the formation of a plasma sheath within the surrounding flow field. In order to characterize such communication blackout phases, this work presents a numerical methodology combining Computational Fluid Dynamic (CFD) simulations of ionized chemically reacting entry flows by means of Computational Object-Oriented Libraries for Fluid Dynamics (COOLFluiD) and a ray tracing analysis by means of the newly developed BlackOut RAy Tracer (BORAT). The latter is based on the numerical solution of the 3D Eikonal system of equations, offering a fast, efficient and accurate method to analyse the interaction between electromagnetic signals and weakly ionised plasmas. The proposed methodology, and BORAT in particular, is first verified on popular benchmark cases and then used to analyse the European Space Agency (ESA) 2016 ExoMars Schiaparelli entry flight into Martian environment. The corresponding results demonstrate the validity of the proposed ray tracing approach for predicting communication blackout, where signals emitted from the on-board antenna undergo reflection and refraction from the plasma surrounding the entry vehicle, and the advantage of a 3D approach for analysing real flight configuration

Magnetohydrodynamic Enhanced Entry System for Space Transportation (MEESST) as a Key Building Block for Future Exploration Missions

Aside from the launch environment, atmospheric re-entry imposes one of the most demanding environments which a spacecraft can experience. The combination of high spacecraft velocity and the presence of atmospheric particles leads to partially ionised gas forming around the vehicle, which significantly inhibits radio communications, and leads to the generation of high thermal loads on the spacecraft surface. Currently, the latter is solved using expensive, heavy, and often expendable thermal protection systems (TPS). The use of electromagnetic fields to exploit Magnetohydrodynamic (MHD) principles has long been considered as an attractive solution for this problem. By displacing the ionised gas away from the spacecraft, the thermal loads can be reduced, while also opening a magnetic window for radio waves, mitigating the blackout phenomenon. The application of this concept has to date not been possible due to the large magnetic fields required, which would necessitate the use of exceptionally massive and power-hungry copper coils. High Temperature Superconductors (HTS) have now reached industrial maturity. HTS coils can now offer the necessary low weight and compactness required for space applications. The MEESST consortium the has been awarded a grant from the EU Horizon 2020 programme for the development and demonstration of a novel HTS-based re-entry system based with its foundation on MHD principles. The project will first harmonize existing numerical codes, and then design, manufacture, and test a HTS magnet. The study shows that the use of MEESST technology can have a positive impact on the cost-effectiveness and available payload of interplanetary missions

On the accuracy of the SGP4 to predict stellar occultation events using ENVISAT/GOMOS data and recommendations for the ALTIUS mission

In preparation for the operations of the ALTIUS mission, research is carried out to assess the accuracy of the SGP4 orbital propagator in predicting stellar occultation events. The quantification of the accuracy and its consequent improvement will enable reliable measurement planning and, therefore, maximize the number of measurements. To this end, predictions are made for the timing of occultations for the GOMOS instrument on-board the ENVISAT, which are then compared to actual occultation occurrences. It is found that the error is substantial but follows a trend that can be interpolated. This enables devising a method for highly accurate predictions given a sufficient number of data points. Statistically significant results for the accuracy of the propagator and a calibration method are presented. Recommendations for a measurement planning procedure of ALTIUS are formulated

A Magnetohydrodynamic enhanced entry system for space transportation: MEESST

This paper outlines the initial development of a novel magnetohydrodynamic (MHD) plasma control system which aims at mitigating shock-induced heating and the radio-frequency communication blackout typically encountered during (re-)entry into planetary atmospheres. An international consortium comprising universities, SMEs, research institutions, and industry has been formed in order to develop this technology within the MEESST project. The latter is funded by the Future and Emerging Technologies (FET) program of the European Commission’s Horizon 2020 scheme (grant no. 899298). Atmospheric entry imposes one of the harshest environments which a spacecraft can experience. The combination of hypersonic velocities and the rapid compression of atmospheric particles by the spacecraft leads to high-enthalpy, partially ionised gases forming around the vehicle. This inhibits radio communications and induces high thermal loads on the spacecraft surface. For the former problem, spacecraft can sometimes rely on satellite constellations for communicating through the plasma wake and therefore preventing the blackout. On the other hand, expensive, heavy, and non-reusable thermal protection systems (TPS) are needed to dissipate the severe thermal loads. Such TPS can represent up to 30% of an entry vehicles weight, and especially for manned missions they can reduce the cost- efficiency by sacrificing payload mass. Such systems are also prone to failure, putting the lives of astronauts at risk. The use of electromagnetic fields to exploit MHD principles has long been considered as an attractive solution for tackling the problems described above. By pushing the boundary layer of the ionized gas layer away from the spacecraft, the thermal loads can be reduced, while also opening a magnetic window for radio communications and mitigating the blackout phenomenon. The application of this MHD-enabled system has previously not been demonstrated in realistic conditions due to the required large magnetic fields (on the order of Tesla or more), which for conventional technologies would demand exceptionally heavy and power-hungry electromagnets. High-temperature superconductors (HTS) have reached a level of industrial maturity sufficient for them to act as a key enabling technology for this application. Thanks to superior current densities, HTS coils can offer the necessary low weight and compactness required for space applications, with the ability to generate the strong magnetic fields needed for entry purposes. This paper provides an overview of the MEESST project, including its goals, methodology and some preliminary design considerations

A Magnetohydrodynamic enhanced entry system for space transportation: MEESST

This paper outlines the initial development of a novel magnetohydrodynamic (MHD) plasma control system which aims at mitigating shock-induced heating and the radio-frequency communication blackout typically encountered during (re-)entry into planetary atmospheres. An international consortium comprising universities, SMEs, research institutions, and industry has been formed in order to develop this technology within the MEESST project. The latter is funded by the Future and Emerging Technologies (FET) program of the European Commission’s Horizon 2020 scheme (grant no. 899298). Atmospheric entry imposes one of the harshest environments which a spacecraft can experience. The combination of hypersonic velocities and the rapid compression of atmospheric particles by the spacecraft leads to high-enthalpy, partially ionised gases forming around the vehicle. This inhibits radio communications and induces high thermal loads on the spacecraft surface. For the former problem, spacecraft can sometimes rely on satellite constellations for communicating through the plasma wake and therefore preventing the blackout. On the other hand, expensive, heavy, and non-reusable thermal protection systems (TPS) are needed to dissipate the severe thermal loads. Such TPS can represent up to 30% of an entry vehicles weight, and especially for manned missions they can reduce the cost- efficiency by sacrificing payload mass. Such systems are also prone to failure, putting the lives of astronauts at risk. The use of electromagnetic fields to exploit MHD principles has long been considered as an attractive solution for tackling the problems described above. By pushing the boundary layer of the ionized gas layer away from the spacecraft, the thermal loads can be reduced, while also opening a magnetic window for radio communications and mitigating the blackout phenomenon. The application of this MHD-enabled system has previously not been demonstrated in realistic conditions due to the required large magnetic fields (on the order of Tesla or more), which for conventional technologies would demand exceptionally heavy and power-hungry electromagnets. High-temperature superconductors (HTS) have reached a level of industrial maturity sufficient for them to act as a key enabling technology for this application. Thanks to superior current densities, HTS coils can offer the necessary low weight and compactness required for space applications, with the ability to generate the strong magnetic fields needed for entry purposes. This paper provides an overview of the MEESST project, including its goals, methodology and some preliminary design considerations