Autonomous Trustworthy Monitoring and Diagnosis of CubeSat Health (AtMonSat)

Report (2022)

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 ... [more ▼]

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. [less ▲]

A Magnetohydrodynamic enhanced entry system for space transportation: MEESST

in Journal of Space Safety Engineering (2022)

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 ... [more ▼]

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. [less ▲]

The “Daffodil” Mission: GNSS-Reflectometry with a 1.5U CubeSat

in Proceedings of the 73rd International Astronautical Congress (2022)

Special Issue on Very Low Earth Orbit Missions and Technologies

in Roberts, Peter C. E.; Herdrich, Georg; Thoemel, Jan (Eds.) Special Issue on Very Low Earth Orbit Missions and Technologies (2022)

The Effect of an Applied Magnetic Field onto the Re-entry Radio Communication Blackout

in Proceedings of the 2nd International Conference on Flight Vehicles, Aerothermodynamics and Re-entry Missions Engineering (2022)

Solar-Aerodynamic Formation Flight for 5G Experiments

in Proceedings of the 12th European CubeSatSymposium (2021, November 15)

Radio communication blackout analysis of ExoMars re-entry mission using raytracing method

in Radio communication blackout analysis of ExoMars re-entry mission using raytracing method (2021, January)

This work presents a numerical methodology to properly characterize and predict the ommunications blackout phase of the ExoMars Schiaparelli Martian atmospheric re-entry flight. The focus of this work ... [more ▼]

This work presents a numerical methodology to properly characterize and predict the ommunications blackout phase of the ExoMars Schiaparelli Martian atmospheric re-entry flight. The focus of this work lies on the use of an optical ray tracing technique to describe the electromagnetic waves behaviour within the ionized wake flow of the vehicle. Bi-dimensional hypersonic CFD simulations are performed over the ExoMars Schiaparelli module at different trajectory points with the COOLFluiD aerothermodynamics Finite Volume solver coupled with the thermochemistry library PLATO. Subsequently, a ray tracing algorithm is applied to examine the propagation of electromagnetic waves and their interaction with the re-entry wake flow of the ExoMars vehicle. In this work, results are presented at three different trajectory points, characterized by different ionization levels of the flow. The results show how this methodology is suited to analyze blackout re-entry phases providing useful information on electromagnetic waves behaviour in ionized plasma re-entry flows. [less ▲]

Blackout analysis of Mars entry missions

in Journal of Fluid Mechanics (2020)

A new methodology to accurately and efficiently examine the radio frequency blackout phenomenon during the hypersonic reentry process is introduced and validated. The current state-of-the-art ... [more ▼]

A new methodology to accurately and efficiently examine the radio frequency blackout phenomenon during the hypersonic reentry process is introduced and validated. The current state-of-the-art thermochemical modelling of CO2 flows is reviewed and one-dimensional stagnation line studies are performed in order to determine a suitable chemical mechanism for the electron density modelling. Hypersonic computational fluid dynamics (CFD) simulations are performed with a simplified chemical model including only neutral species, in order to calculate the flow field surrounding the ExoMars Schiapparelli module in flight conditions. A novel decoupled CFD approach is then applied where the calculation of the electron density is performed separately using a computationally inexpensive Lagrangian approach. Subsequently, a ray tracing algorithm is applied in order to model the propagation of electromagnetic waves in the wake flow past the ExoMars vehicle accounting for collisions between electrons and gas particles. The numerical results of the proposed novel approach for blackout analysis consisting of CFD, Lagrangian and ray tracing algorithms are in good agreement with the flight data. [less ▲]

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

in CEAS Space Journal (2019), 11(2), 147--159

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 ... [more ▼]

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. [less ▲]

Blackout analysis of small cone-shaped reentry vehicles

in Journal of Thermophysics and Heat Transfer (2017), 31(2), 269--282

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 ... [more ▼]

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. [less ▲]