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See detailNvidia Omniverse for Active Space Debris Removal Missions, an Overview
Li, Xiao UL; Richard, Antoine UL; Loumpasefski, Olga-Orsalia UL et al

Scientific Conference (2022, October 13)

Earth orbits have an increasingly worrying space debris pollution problem caused by millions of human-made objects left in space. These are becoming a hazard for current and future space missions. Many ... [more ▼]

Earth orbits have an increasingly worrying space debris pollution problem caused by millions of human-made objects left in space. These are becoming a hazard for current and future space missions. Many solutions to deal with space debris problems have been proposed, including Active Space Debris Removal (ASDR) methods. In this thriving field, various technologies are under development, among them, systems based on tethers, nets, lasers, or robotic arms can be found. However, testing such systems on earth is challenging, recreating space-like conditions, such as accurate contact dynamics under microgravity, is particularly difficult. Nonetheless, it is of paramount importance to offer testing environments for clean space technologies, as space is unforgiving, and space devices must go through thorough evaluation processes to ensure peak efficiency. The HELEN project aims at fulfilling this very need. Building on one of the most advanced simulation frameworks, it will provide photo-realistic rendering, an accurate physical simulation of the space environment, and eventually, through Hardware-In-the-Loop (HIL), simulation of microgravity in ground facilities. This project is the result of the collaboration between SpaceR (University of Luxembourg), and Spacety (Industry). This simulation will be used to test FlexeS, an ASDR capturing system, which is under development. In HELEN, the accuracy of the physics is particularly important, as FlexeS will be validated through simulated HIL scenarios. Hence, a lifelike depiction of the microgravity environment, as well as the collisions, is critical. Moreover, to intercept and grab the debris FlexeS will rely on computer vision algorithms, thus photo-realistic graphics, allowing for lifelike visualizations are required. Furthermore, for future HIL testing, the ROS bridge and real-time communication capacity are crucial to connect the virtual world with the Zero-G robotic facility of the University of Luxembourg. In such a manner, FlexeS will be visualized in the space surroundings while simultaneously undergoing hardware experiments. With all these constraints in mind, Nvidia's Issac Sim was selected to create on-orbit dynamic scenarios. It not only meets all the requirements above but also provides a variety of sensors. Consequently, HELEN is creating on-orbit simulations featuring a CubeSat embedded with FlexeS, and debris circling the Earth. The scenarios showcase the digital twin of the capturing system intercepting debris, corresponding to the approaching phase in ASDR missions. Visually speaking, the RTX render engine allows for photo-realistic image generation. Regarding the motion of these objects, force-based astrodynamics is implemented into the simulation following the gravitational equation. Faithful velocities, position, and contacts are inferred by Nvidia's physics engine, PhysX. Scaled real-life values are used for the mass, as well as the orbital velocity and altitude. Thus, accurate simulations of contact dynamics between the system and the debris can be achieved. In the future, using a ROS bridge, the simulation will be connected to the HIL testing system of the Zero-G facility, amounting to a wholesome ASDR testing framework. Overall, the realistic simulations created with Isaac Sim are promising for analyzing clean space technologies. They combine photo-realistic scenes, accurate physics, and in the future, a means to test real hardware systems. [less ▲]

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See detailConcept of an Active Debris Removal 2-step capturing system for small satellites in Low Earth Orbit
Hubert Delisle, Maxime UL; Martinez Luna, Carol UL; Yalcin, Baris Can UL et al

Scientific Conference (2022, October 12)

Space debris brings up two main critical issues: not only a non-sustainable space environment for satellite missions, with orbit saturation, but also the creation of an unsafe place for human-related ... [more ▼]

Space debris brings up two main critical issues: not only a non-sustainable space environment for satellite missions, with orbit saturation, but also the creation of an unsafe place for human-related space missions. Despite being extremely challenging, catching autonomously and harmlessly an uncooperative object tumbling at high velocity demand reliability, compliance, and robustness. Grasping an object in microgravity means having control during the impact, but also keeping the link between the chaser satellite and the debris secure enough to handle the deorbiting phase. Supposing that the GNC installed tackles the synchronization with the debris rotation, so that only a linear translation is necessary to capture, three main problems can occur. The first problem can occur at the impact between the servicer and the debris. Due to the motion-reaction law, the debris could be pushed away if the capturing system does not prevent that motion. Besides, a high stiffness of the system, added to an unexpected strong impact, could damage either the servicer and/or the debris, resulting in a mission failure. Moreover, the need for a secure attach is required to go-on with the deorbit phase without losing the debris. That’s why, thanks to the fruitful collaboration between industry and academia (Spacety Luxembourg - SpaceR research group at the University of Luxembourg), a cutting-edge concept of a two-step capturing mechanism is being designed. Data analysis of trackable objects in LEO reveals an abundant number of CubeSat-shaped satellites, that future constellations might also take advantage of. Consequently, the concept presented is focusing on capturing these, at their end of life. A first ‘soft capture’ ensures that the debris is received softly while dampening any vibrations generated. A gecko-inspired adhesive surface will first receive the debris, preventing it from being pushed away. The property of such dry adhesive is that they do not require a high preload to stick to the surface, while having a very strong adhesion. To absorb most of the vibrations or movements due to the first impact, a compliant mechanism will be integrated behind the adhesive part. To that extent, if the alignment is not perfect, the system has some degrees of freedom, so that no damage can be generated. This compliant and sticky system would prevent the first main two issues of capturing an uncooperative target in microgravity. Then, a ‘hard capture’ secures the debris so that it would be deorbited without being released on the way. This part of the system would either gently squeeze the debris, using controlled adhesive flexible arms, or encircle it, and would be designed in compliance of ESA guidelines for demise. A two-step capturing mechanism is here proposed, taking advantage of bio-inspired dry adhesive technology, and compliant mechanisms, while having ESA guidelines in mind. Bringing the advantage of removing a vast range of objects in orbit, it also allows a reliable capturing, removing risks of generating more debris. Later works would bring attention to architecture that would fit more than a box shape. [less ▲]

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See detailEmulating Active Space Debris Removal Scenarios in Zero-G Lab
Li, Xiao UL; Hubert Delisle, Maxime UL; Yalcin, Baris Can UL et al

Presentation (2022, June 02)

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See detailExploring NVIDIA Omniverse for Future Space Resources Missions
Li, Xiao UL; Yalcin, Baris Can UL; Christidi-Loumpasefski, Olga-Orsalia UL et al

Poster (2022, May 03)

The resources of space offer a means to enable sustainable exploration of the Moon and Solar System beyond, thus developing space resource technologies is becoming a major topic for space-related activity ... [more ▼]

The resources of space offer a means to enable sustainable exploration of the Moon and Solar System beyond, thus developing space resource technologies is becoming a major topic for space-related activity internationally. However, verifying and validating such systems on Earth conditions is challenging due to the difficulty of filling the sim2reality gap by creating the exact environment. We hypothesize that having on-ground experimental facilities that integrate high-fidelity simulation and physical systems will enable close-to-real testing, speeding up the transition between space technology development and deployment stages. NVIDIA Omniverse recently gained interest to create photorealistic environments, and it is a promising tool to simulate space-related scenarios with high fidelity. Physically accurate and faithful on-orbit scenarios could be generated in Omniverse Create by integrating PhysX physics core and Pixar Universal Scene Description. Omniverse also includes a robotic simulator that connects to physical robotic systems. Various connectors between Omniverse and other platforms such as Unreal Engine, Blender, Autodesk, ParaView, and online collaboration capacity offer the possibility of importing models of space mission components, space scenes, and scientific data into Omniverse. NVIDIA Omniverse seems auspicious in terms of developing high-fidelity photorealistic simulations. In the HELEN project between SpaceR and Spacety, we are developing a close-to-real testing environment for validating debris removal technology. Within this project, we will explore the potential of Omniverse to integrate virtual and physical components, i.e., high-fidelity photorealistic on-orbit simulations with the Zero-G lab facility, for creating reliable testing conditions to reduce the sim2reality gap. SIL and HIL testing architectures for space systems will be developed using software such as MATLAB/Simulink. Moreover, the robotic systems of the Zero-G lab can be linked to the Omniverse’s robotic simulator using its ROS & ROS2 bridge. The figure presents an overview of Omniverse under the scope of the HELEN project. HELEN will show the combination of photorealistic simulations using Omniverse, SIL, and HIL with the Zero-G lab creates a high-fidelity testing environment for future space resources technology. We also believe that the number of human-made objects orbiting the Earth constitutes a great potential for the recovery of their resources. Most of those include valuable materials (Aluminum, Gold, Silver). Therefore, in the future, debris mitigation efforts can target the recovery of such resources, as pointed out in [1]. Reference:[1] Frank Koch, The Value of Space Debris (2021), 8th European Conference on Space Debris [less ▲]

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