Impact of Gravity on Gas Permeability and Mechanical Properties of Dust Aggregates

Researchers have conducted an investigation into the gas permeability and mechanical properties of dust grain aggregates under hyper- and zero-gravity conditions. The study, led by Holly L. Capelo and 15 other authors, utilized 12 granular samples to simulate planetesimal dust regoliths. The experiments were performed using parabolic flights to assess how gravitational compression affects gas permeation, which in turn impacts the equilibrium state of low-gravity objects.

Key findings from the study include:

• Gas Permeability: As confinement pressure increases with gravitational load and mass flow, gas permeability and average pore space decrease. This suggests that a planetesimal's dust-compaction history can limit sub-surface volatile outflows.
• Pressure Gradient and Tensile Strength: The derived pressure gradient enables the determination of tensile strength for asteroid regolith simulants with cohesion. This approach is valuable for studying dust-layer properties under confinement pressures similar to those on planetesimal surfaces, aiding in modeling their collisional evolution.
• Flow Symmetry Breaking: A dynamical flow symmetry breaking was observed when granular material moved against the pressure gradient, even at low Reynolds numbers. This indicates that Stokes numbers for drifting dust aggregates near the Stokes-Epstein transition require a drag force modification based on permeability.

These findings have significant implications for understanding the physical properties and behavior of dust aggregates in space environments, particularly in the context of planetesimal formation and evolution. The study provides new insights into the aerodynamics of dust grains and the mechanical properties of regolith under varying gravitational conditions.

The full paper, titled Gas permeability and mechanical properties of dust grain aggregates at hyper- and zero-gravity, is available on arXiv and was authored by Holly L. Capelo, Jean-David Bodénan, Martin Jutzi, Jonas Kühn, Romain Cerubini, Bernhard Jost, Linus Stöckli, Stefano Spadaccia, Clemence Herny, Bastian Gundlach, Günter Kargl, Clément Surville, Lucio Mayer, Maria Schönbächler, Nicolas Thomas, and Antoine Pommerol.