Expert for Distributed Satellite Systems

Small satellites that find and collect space debris: Mohamed Khalil Ben-Larbi is working towards this goal. He is the new Professor of Space Informatics and Satellite Systems at the University of Würzburg.

Humanity also leaves its rubbish in space: discarded satellites and debris orbit the earth in large numbers. There are an estimated 26,000 debris objects larger than ten centimetres. There are also millions of smaller pieces. And because new satellites are always being built, the population of space debris is constantly growing.

Space debris jeopardises ongoing space missions and operational satellites: In the event of a collision, even small debris pieces can cause catastrophic damage if they hit at high speed, potentially leading to total mission loss. Addressing this challenge involves exploring methods for debris removal. One promising solution is deploying autonomous fleets of small satellites to track down and collect debris– some of which could possibly be recycled or even repaired. This would be a step towards more sustainability in space operations.

Aerospace engineer Mohamed Khalil Ben-Larbi is working in this field. He moved from the Technical University of Berlin to Julius-Maximilians-Universität (JMU) Würzburg in Bavaria, Germany, in September 2024. He now researches and teaches here as Professor of Space Informatics and Satellite Systems.

Current Focus on Rendezvous and Docking

Ben-Larbi is generally interested in distributed systems made up of small satellites – these are groups of autonomous satellites that work together in a coordinated manner. He develops models, components and algorithms to further improve the guidance, navigation and control of such systems. His current focus is on rendezvous and docking manoeuvres – i.e. locating, approaching, and docking with target objects in space.

‘Autonomous navigation, motion planning and control to approach target objects while avoiding collisions with the target or other objects,’ is how the professor describes the first requirement for small satellites that are to collect space debris. These tasks must be performed completely autonomously on board the satellites. AI technologies are also used for this.

Adhesive Surfaces Coated with Gecko Materials

Mohamed Khalil Ben-Larbi also uses the latest technologies for the docking manoeuvres. His concept consists of satellites with contact surfaces coated with so-called gecko materials – silicones with specially microstructured surfaces. If they come into contact with other objects under carefully selected relative motion conditions, these surfaces adhere effectively – similar to the natural adhesion mechanism of gecko feet.

Gecko materials have a number of advantages: they are easy to produce, inexpensive and do not require electrical power. If a docking attempt fails, the experiment can be repeated as often as required. The JMU researcher is collaborating with teams from TU Berlin and the Leibniz Institute for New Materials in Saarbrücken on the development and application of these materials.

The professor’s team plans to test how well autonomous docking works under microgravity conditions on the International Space Station (ISS) at the end of 2025. Two Astrobees built and operated by NASA – cube-shaped, free-floating robots that support the crew of the ISS in their everyday tasks – will be available for this purpose. One Astrobee will assume the role of a broken satellite, while the other will be equipped with the docking mechanism and the appropriate algorithms.

Curriculum Vitae of the New Professor

Mohamed Khalil Ben-Larbi, born in 1982, grew up in Tunis (Tunisia). After leaving school, he went to Germany and studied aerospace engineering at the University of Stuttgart. This was followed by scientific positions at Airbus Defence and Space and the German Aerospace Centre in the field of helicopter technology.

In 2015, he moved to the Technical University of Braunschweig, where he also completed his doctorate. While there, he worked on the guidance, control and docking of small satellites with the aim of removing space debris. From 2021, Ben-Larbi then headed the SmallSat Rendezvous & Robotics Group at the Technical University of Berlin. From there, he moved to the Würzburg Chair of Space Informatics and Satellite Systems in September 2024.

First Internship for Master’s Students

Mohamed Khalil Ben-Larbi is currently offering a first internship for students on the JMU Master’s degree programmes in Computer Science and Satellite Technology. The aim is to estimate and track the position and orientation of non-cooperative target objects in space using on-board equipment. ‘The students are familiarising themselves with a crucial technology to enable autonomous maintenance work in orbit as well as active debris removal.’

Wissenschaftliche Ansprechpartner:

Prof. Dr.-Ing Mohamed Khalil Ben-Larbi, Institute of Computer Science, University of Würzburg, T +49 931 31-81511, khalil.ben-larbi@uni-wuerzburg.de

http://www.uni-wuerzburg.de