Periodic Reporting for period 1 - TRACES (Transitions in Rubble-pile Asteroid Chaotic Environment and granular Structures)
Reporting period: 2023-06-01 to 2025-11-30
We are now living exciting times for asteroid exploration. The increasing availability of in-situ observation data, providing unprecedented level of detail, makes the study of asteroids an exciting and living frontier. Asteroids are rubble piles, i.e. gravitational aggregates of loosely consolidated material. However, no direct measurements of asteroids’ interior exist and little is known about the mechanisms governing their formation and evolution. Not only limited by a lack of data, the understanding of asteroids’ properties is challenged at a fundamental level by their rubble-pile nature. This makes their dynamics subject to the laws of granular mechanics, one of the major unsolved problems in physics.
TRACES enables a new paradigm for the characterization of granular systems in asteroid-related scenarios. The ambition is to demonstrate that the macroscopic behaviour of granular media in asteroid environment can be inferred from local properties of the grain. The methodology lays its foundation on a cutting-edge simulation tool, able to resolve the dynamics of grains to particle-scale precision, and a theoretical framework, able to decode the chaotic nature of particle-scale dynamics.
TRACES’ hypothesis is validated through theoretical, numerical and experimental work. The ability of the methodology to characterize and identify transitions between dynamical regimes of granular media, is tested gradually, for increasing levels of realism, ranging between proof-of-concept, laboratory scenarios involving experiments in vacuum/low-g, and full-scale scenarios involving asteroid mission data.
TRACES has the potential to enable the characterization of surface and internal properties of asteroids with limited observation data. This will play a crucial role to enable the next breakthrough in asteroid science, as well as efficient/cost-effective design of the next generation of space missions to explore and exploit asteroids, including planetary defence applications.
TRACES enables a new paradigm for the characterization of granular systems in asteroid-related scenarios. The ambition is to demonstrate that the macroscopic behaviour of granular media in asteroid environment can be inferred from local properties of the grain. The methodology lays its foundation on a cutting-edge simulation tool, able to resolve the dynamics of grains to particle-scale precision, and a theoretical framework, able to decode the chaotic nature of particle-scale dynamics.
TRACES’ hypothesis is validated through theoretical, numerical and experimental work. The ability of the methodology to characterize and identify transitions between dynamical regimes of granular media, is tested gradually, for increasing levels of realism, ranging between proof-of-concept, laboratory scenarios involving experiments in vacuum/low-g, and full-scale scenarios involving asteroid mission data.
TRACES has the potential to enable the characterization of surface and internal properties of asteroids with limited observation data. This will play a crucial role to enable the next breakthrough in asteroid science, as well as efficient/cost-effective design of the next generation of space missions to explore and exploit asteroids, including planetary defence applications.
TRACES implements theoretical, numerical and experimental work to address the problem of characterizing the dynamics of granular media in the asteroid environment. In particular, TRACES' hypothesis is that granular media can be characterized by improving the realism of models for the local-scale interactions between individual fragments. Theoretical work involves the study of granular systems using techniques of chaotic and nonlinear dynamical systems, while experimental work, including micro-g test campaigns (drop tower and parabolic flight) is used to calibrate the numerical models to fragment-scale precision. The hypothesis is finally validated at a full-scale level, using data from asteroid exploration missions, such as ESA's Hera and RAMSES.
Figure 1 shows the construction of the digital model of the cobbles used duing the micro-g drop tower experiments, using a 3D scanner. Figure 2 shows the setup of the drop tower experiment, where two cobbles are placed into bins inside a vacuum chamber. The cobbles are then released with a small relative velocity to achieve a low-speed collision in micro-g conditions and vacuum. Cameras are used to retrieve the cobbles position and orientation before, during and after the collision. Figure 3 shows the setup of the parabolic flight experiment, where a landing pad will be used to interact with a granular bed in micro-g and vacuum environment.
Figure 1 shows the construction of the digital model of the cobbles used duing the micro-g drop tower experiments, using a 3D scanner. Figure 2 shows the setup of the drop tower experiment, where two cobbles are placed into bins inside a vacuum chamber. The cobbles are then released with a small relative velocity to achieve a low-speed collision in micro-g conditions and vacuum. Cameras are used to retrieve the cobbles position and orientation before, during and after the collision. Figure 3 shows the setup of the parabolic flight experiment, where a landing pad will be used to interact with a granular bed in micro-g and vacuum environment.
TRACES provides a new framework for granular mechanics in asteroid environment. This is extremely ambitious, but has a huge potential for disruptive innovation across multiple disciplines. A direct impact will be on asteroid science and exploration: for example, surface interaction and manipulation rely critically upon the knowledge of the mechanical response of asteroid material. This is crucial for e.g. asteroid in-situ resources utilization and planetary defense. Furthermore, granular media are everywhere in our daily life, extending further the possible impact of the project. Characterizing asteroid granular media is now the missing piece to enable the next breakthroughs in the field.
Preliminary results shows the capability of the methodology developed to describe the global behavior of granular material. The results of the experimental drop tower campaign shows that the tool is able to reproduce the motion of the cobbles and their low-speed collision. This has also allowed to fine tune contact models, to be used in future studies involving more complex scenarios.
Preliminary results shows the capability of the methodology developed to describe the global behavior of granular material. The results of the experimental drop tower campaign shows that the tool is able to reproduce the motion of the cobbles and their low-speed collision. This has also allowed to fine tune contact models, to be used in future studies involving more complex scenarios.