Stefano Rossi

Ecole Polytechnique Federale de Lausanne, Swiss Space Center, Faculty Member

Ecole Polytechnique Federale de Lausanne, E Space, Faculty Member

Università degli Studi di Padova, CISAS, Graduate Student

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email: [email protected]
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I’m a young engineer passionate for challenges and for space.
My studies are focused on Attitude Determination and Control Subsystems and Robotics for Space.
I have worked on the analysis of the flight data of SwissCube. As AOCS System Engineer I was responsible for the next CubeSat mission of the Swiss Space Center - CubETH- presenting several papers at Conferences and AOCS workshops.
I challenged myself in Management, Administration and Business Development for Space Applications, working at the Swiss Space Center as Swiss National Affairs Coordinator for the Swiss Space Center.
I was responsible of several small projects for space application in collaboration with ESA as Technical and Contract Officer.
In parallel I worked in the Business Development side, helping small and bigger companies to face their technologies for space applications, preparing proposals and collaborating at the same time as consulting for space technologies.
Last but not least, I loved working in a young and dynamic team. I've supervised several students at the EPFL during their semester and master projects improving my teamwork and management skills.
I recently started a new adventure at ELSE SA as system engineer for ADCS and Mission Design for the M2M Nano-satellites: a Global Coverage for Your Connected Objects at Ground-Low Cost. I’m as well continuing the business development in this startup.
My wish is to continue "my journey through space" and its challenges, but extremely open even to other thematics that can inspire me.
My secret love is Triathlon and Ironman competitions, challenging myself in endurance competitions where body and mind have to find the right balance to reach the result.

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Papers by Stefano Rossi

THE SWISSCUBE’S TECHNOLOGIES RESULTS AFTER FOUR YEARS OF FLIGHT

SwissCube: the first entire Swiss satellite is now on orbit; planned to operate for at least twel... more SwissCube: the first entire Swiss satellite is now on orbit; planned to operate for at least twelve months, it will have four years in the 23th of September; four years of data and results from the space and from its payload and operations. As cubesat made by students it is a good result: more than 200 students worked on it before and after the launch in 2009, designing, testing and validating the data from the instruments on board. In this paper it is presented a general description of the cheap technology used for SwissCube, giving a particular attention to the tests done before and after flight, describing the payload mounted and the results achieved. This study wants to show the good results and the errors made, the good operations and the malfunctions during the flight in order to spread the technology used for future CubeSats. As example, results obtained by a cheap and an easy B-dot controller using magentotorquers are here presented; camera's pictures, gyros, magneto-meters, sun-sensors and thermometers results are also shown, giving particular relevance to the performances and to the difficulties had during the years. The goal of SwissCube was mainly educational, teaching and showing to students how to built a Nano/Pico satellite with available just 10x10x10cm and 1kg and this study wants to show the results achieved during the design and the test according to the flight data, in order to increase the technology and the “know-how" experience of CubeSats platforms.

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CUBETH ADCS DESIGN, IMPLEMENTATION AND VALIDATION TESTS

by Stefano Rossi, Raph Zufferey, Amiguet Jérôme, Valceschini Raphaël, Starein Marcel, Guillaume Faure, Gaetan Burri, and Beat Geissmann

CubETH is a one unit CubeSat developed in collaboration between EPFL (Lausanne) and ETH Zurich. T... more CubETH is a one unit CubeSat developed in collaboration between EPFL (Lausanne) and ETH Zurich. The main objective of CubETH is to demonstrate the use of commercial GNSS receivers in space and test Precision Orbit Determination algorithms. One of the key driving requirements is to provide nadir pointing with a 20 degrees of precision and rotation rate less than 2 degree / second, in order to track GNSS constellation satellites. In this paper the solutions for the ADCS and the designed operatives modes are described. The ADCS shall provide for the Payload a nadir pointing with relaxed requirements, and in order to do that the team paid particular attention to the validation of the chosen hardware and software solutions. According the experience of SwissCube, its five years of data collected and lessons learned, we have started a vigorous process of design, implementation and validation for ADCS with several test setups and characterizations for sensors and actuators. We present the ADCS focusing mainly in the implementation, in the errors encountered and the process of validation in our test setups. A ball bearing with a Helmotz Cage has been used to validate the functionality of implemented algorithms (B-dot, TRIAD and an Extended Kalman Filter), results will be presented. Sensors calibrations and characterizations are addressed giving particular emphasis on their thermal drifts that can affect the determination process. Tests in Thermal Chambers show some interesting behaviours of the selected COTS sensors. A vigorous test campaign has been done on the first batch of Sun Sensors revealing not negligible effects that should be taken into account during final implementation. Even the actuators (magnetorquers) have been heavily tested to characterize their dipoles; tests revealed a really good match between the theoretical models and the hardware. Several test setups have been designed in order to characterize separately COTS components, and actuators for ADCS but more remarkable is the effort that has been spent for the validation of the whole ADCS system: one of the most challenging subsystem for CubeSat is the ADCS due to the several test setup and validations necessary to prove its functionality.

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THERMAL MODEL FOR CUBESAT: A SIMPLE AND EASY MODEL FROM THE SWISSCUBE’S THERMAL FLIGHT DATA

After the launch in the 23 September of 2009, SwissCube has downloaded a big amount of data from ... more After the launch in the 23 September of 2009, SwissCube has downloaded a big amount of data from space until today, some of them are very interesting for education, and they can open possibilities of learning some important lessons for space subsystems and future cubesat’s designs. In particular, here are taken into account four years of flight data coming from the temperature sensors of SwissCube that have collected more than 200 full orbits in terms of temperatures from solar panels and from inner parts as electronic boards and batteries. With more than twenty sensors and in accordance with the illumination data coming from the solar panels, this paper wants to present an interesting thermal model for cubesats. The model, based on the finite elements approach, describes the evolution of the temperature during the orbit of two or more nodes (thermal elements) taking into account time of illumination, light and eclipses. The math and the heat transfer’s equations are here presented in order to show how to develop a reliable and easy thermal model without going further in a complex finite-elements software. The goal of the development of this simple model, indeed, is the student education. As it has been a student work, it can be reused for other student-cubesat’s projects just manipulating some parameters or equations, having always an eye on how the thermal propagation works in space and how it is implemented in a software. The key points are the simplicity and the reliability due to validation from four years of thermal data coming from SwissCube. At the same time the possibility of increasing the complexity and the precision of the model with more than two nodes is still an open door. Results and simulations are here presented in accordance with a validation from the SwissCube’s flight data, showing the pros and the cons of this model.

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CUBETH SENSOR CHARACTERIZATION: SENSOR ANALYSIS REQUIRED FOR A CUBESAT MISSION

by Stefano Rossi and Gaetan Burri

Swiss Federal Universities of Lausanne and Zurich have initiated a new 1U CubeSat project. The ma... more Swiss Federal Universities of Lausanne and Zurich have initiated a new 1U CubeSat project. The main objective of the CubETH is to demon- strate use of commercial GNSS receivers in space and test Precision Or- bit Determination algorithms. One of the key driving requirements is to provide zenith pointing with a 20 degrees of precision and rotation rate less than 2 degree / second, in order to track GNSS constellation satel- lites. This paper will describe details of Attitude Determination and Con- trol Subsystem (ADCS) based on magnetotorquers in order to satisfy the science requirements. We will discuss lessons learned from the ADCS implementation on the first Swiss nanosatellite SwissCube (in operation since 2009) and we present the flat shaped magnetotorquers (MTQs) de- signed in the laboratories of the Ecole Polytechinque Federale de Lau- sanne (EPFL) in Switzerland, detailing design, test setup and procedures performed. The main lesson learned from SwissCube is to establish vig- orous testing procedures for all sensors. This paper will present tests set- up and procedures used for the present and the future tests in the labora- tories of the Swiss Space Center that take experience from the lessons learned. We describe tests set-up, interfaces and procedures performed to establish trade-off study for the sensors: static and dynamic characteriza- tions, temperature behaviors and others. The paper gives to the CubeSat community a validated and simple process to characterize the sensors for the attitude determination.

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CUBETH MAGNETOTORQUERS: DESIGN AND TESTS FOR A CUBESAT MISSION

by Stefano Rossi and Soudan Georges

Swiss Federal Universities of Lausanne and Zurich have initiated a new 1U Cu- beSat project. The ... more Swiss Federal Universities of Lausanne and Zurich have initiated a new 1U Cu- beSat project. The main objective of the CubETH is to demonstrate use of com- mercial GNSS receivers in space and test Precision Orbit Determination algo- rithms. One of the key driving requirements is to provide zenith pointing with a 20 degrees of precision and rotation rate less than 2 degree / second, in order to track GNSS constellation satellites. This paper will describe details of Attitude Determination and Control Subsystem (ADCS) based on magnetotorquers in or- der to satisfy the science requirements. We will discuss lessons learned from the ADCS implementation on the first Swiss nanosatellite SwissCube (in operation since 2009) and we present the flat shaped magnetotorquers (MTQs) designed in the laboratories of the Ecole Polytechinque Federale de Lausanne (EPFL) in Switzerland, detailing design, the test setup and t procedures performed.
We present theoretical calculations for the magnetotorquer parameters, simula- tions, details of manufacturing and results of testing done in the shielded room of the Ecole Poly-techinque Federale de Lausanne. Testing shows a 93% of match be-tween the 3D model and tests done with the magnetic probe on the new de-sign prepared for CubETH, where the design slightly changed from the previous shape of SwissCube.
The paper presents the description of the manufacturing and the process fol- lowed in order to highlight the encountered issues on the magnetotorquers fabri- cation. We address the process to select the proper materials and quantities for the manufacturing of flight and engineering models, ad-dressing the required characteristics for the material selected.

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ROBUST REACTION CONTROL OF SPACE MANIPULATORS

The minimization of the dynamic disturbances transferred to the base spacecraft by a redundant ma... more The minimization of the dynamic disturbances transferred to the base spacecraft by a redundant manipulator during operations is an important issue in space robotic missions, because it leads to reduced energy consumption of the Attitude Control System and, therefore, to an increased system operating life. The use of redundant manipulators makes it possible to perform the required tasks and in the meantime minimize the reactions transferred to the base spacecraft and possibly other additional performance criteria, which can be used to increase the robustness of the solution. A robust solution should at least take into account the joint limits, the joint velocity and acceleration limits, and the avoidance of algorithmic and dynamic singularities. The method proposed in this paper consists in using the recently developed least squares reaction control solution, which can take into account the joint acceleration limits in the real-time solution, and modifying it in order to take into account the joint and the joint velocity limits. The method is based on the concept that it is possible to impose joint and joint velocity limits indirectly, by computing the related joint acceleration limits, which are the ones that are used in the solution algorithm. In this way a robust solution is obtained, which attains a twofold objective: from one side the physical limits of the manipulator joints are taken into accounts, and from the other side the method can be used to avoid manipulator dynamic and algorithmic singularities, thanks to the imposed change of the history in the joint space. The proposed robust reaction control method has been validated by means of software simulations, which helped to demonstrate the proposed concepts and to evaluate their pros and cons.

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CubETH: low cost GNSS space experiment for precise orbit determination

by Volker Gass, Stefano Rossi, Federico Belloni, Reto Wiesendanger, Erich Styger, Klaper Martin Hslu T&a, and Joss Marcel Hslu T&a

CubETH is a project to evaluate and demonstrate possibilities of low-cost GNSS receivers on a nan... more CubETH is a project to evaluate and demonstrate possibilities of low-cost GNSS receivers on a nano-satellite by following the Cubesat standard. The development of this new Swiss cubesat mission is underway at the Swiss Polytechnical Schools, launch is planned for 2016. Scientific goal are: precise orbit determination and estimate of satellite attitude based on a very short baseline together with a number of other experimental measurements. Programmatic goal is to implement this project in cooperation between federal (ETH/EPF domain) and cantonal (FH/HES domain) engineering schools and industrial partners. The educational objective is to involve engineering students from various schools across Switzerland to promote innovative teaching of engineering of complex systems. In this paper, we will discuss performance requirements for the CubETH spacecraft and its payload. We also show how lessons learned from the Swisscube satellite were used for the design and implementation of this proj...

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THE SWISSCUBE’S TECHNOLOGIES RESULTS AFTER FOUR YEARS OF FLIGHT

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CUBETH ADCS DESIGN, IMPLEMENTATION AND VALIDATION TESTS

by Stefano Rossi, Raph Zufferey, Amiguet Jérôme, Valceschini Raphaël, Starein Marcel, Guillaume Faure, Gaetan Burri, and Beat Geissmann

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THERMAL MODEL FOR CUBESAT: A SIMPLE AND EASY MODEL FROM THE SWISSCUBE’S THERMAL FLIGHT DATA

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CUBETH SENSOR CHARACTERIZATION: SENSOR ANALYSIS REQUIRED FOR A CUBESAT MISSION

by Stefano Rossi and Gaetan Burri

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CUBETH MAGNETOTORQUERS: DESIGN AND TESTS FOR A CUBESAT MISSION