LMGC90: a Contact Dynamics open source code for the simulation of granular asteroid with realistic regolith shapes. Application to the accretion process
#1Matthieu Constant(UCL: Université catholique de Louvain)H-Index: 1
#2Frédéric Dubois(CNRS: Centre national de la recherche scientifique)H-Index: 35
Last. Vincent Legat(UCL: Université catholique de Louvain)H-Index: 32
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This paper presents an unresolved computational fluid dynamic–discrete element method (CFD–DEM) model for the simulation of flows mixing fluid and grains. The grains trajectories are solved at a fine scale using a discrete element method. It provides the velocities and the trajectories of the grains with an accuracy that is needed to describe microscopic phenomena like clogging in pipe happening in these flows. Solved at a coarse scale using the finite element method, the fluid motion is deduced...
This paper documents the prearrival planning strategy and analysis for the deployment of rovers on board the Japanese Hayabusa2 asteroid sample return mission. This will allow for rigorous comparison with postarrival results obtained at a future date. Hayabusa2 will arrive at asteroid Ryugu sometime between June and July of 2018. During its stay, the spacecraft will deploy three MINERVA-II rovers and obtain several surface samples. The autonomous Hayabusa2 descent guidance requires the rovers to...
Abstract Geotechnical properties of a granular material affect all surface operations from mobility to landing and excavation. As such, significant efforts to study and model these properties are necessary before sending a spacecraft. Lack of knowledge of regolith material properties adversely affected Apollo, Lunokhod, and Mars Exploration Rover missions; hence additional measures need to be undertaken to prevent potential failures or delays of future missions, in particular missions to explore...
When velocity jumps are occurring, the dynamics is said to be nonsmooth. For instance, in collections of contacting rigid bodies, jumps are caused by shocks and dry friction. Without compliance at the interface, contact laws are not only non-differentiable in the usual sense but also multi-valued. Modeling contacting bodies is of interest in order to understand the behavior of numerous mechanical systems such as flexible multi-body systems, granular materials or masonry. These granular materials...
#2Yuichi Tsuda(JAXA: Japan Aerospace Exploration Agency)H-Index: 19
Last. Satoru Nakazawa(JAXA: Japan Aerospace Exploration Agency)H-Index: 16
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The Hayabusa2 mission journeys to C-type near-Earth asteroid (162173) Ryugu (1999 JU3) to observe and explore the 900 m-sized object, as well as return samples collected from the surface layer. The Haybusa2 spacecraft developed by Japan Aerospace Exploration Agency (JAXA) was successfully launched on December 3, 2014 by an H-IIA launch vehicle and performed an Earth swing-by on December 3, 2015 to set it on a course toward its target Ryugu. Hayabusa2 aims at increasing our knowledge of the early...
Recent developments in powder technology gave birth to a new lubricant—powder lubricant. Compared to liquid lubricant, powder lubricant like graphite powder has several advantages, such as good electrical conductivity and good thermal resistance. Such advantages are especially appreciated in sliding electrical contacts. Thus, the study of the electrical transmission ability of a shearing powder layer under different dynamical constraints appears to have a great interest. Recent works allowed to ...
We present a systematic numerical investigation of the shear strength and structure of granular packings composed of irregular polyhedral particles. The angularity of the particles is varied by increasing the number of faces from 8 (octahedronlike shape) to 596. We find that the shear strength increases with angularity up to a maximum value and saturates as the particles become more angular (below 46 faces). At the same time, the packing fraction increases to a peak value but declines for more a...
NASA selected the OSIRIS-REx Asteroid Sample Return Mission as the third New Frontiers mission in May 2011 [I]. The mission name is an acronym that captures the scientific objectives: Origins, Spectral Interpretation, Resource Identification, and Security-Regolith Explorer. OSIRIS-REx will characterize near-Earth asteroid (101955) 1999 RQ36, which is both the most accessible carbonaceous asteroid [2,3] and one of the most potentially hazardous asteroids known [4]. The primary objective of the mi...
This book brings together in a single volume various methods and skills for particle-scale or discrete-element numerical simulation of granular media. It covers a broad range of topics from basic concepts and methods towards more advanced aspects and technical details applicable to the current research on granular materials. Discrete-element simulations of granular materials are based on four basic models (molecular dynamics, contact dynamics, quasi-static and event driven) dealing with friction...
High-resolution images of the surface of asteroid Itokawa from the Hayabusa mission reveal it to be covered with unconsolidated millimeter-sized and larger gravels. Locations and morphologic characteristics of this gravel indicate that Itokawa has experienced considerable vibrations, which have triggered global-scale granular processes in its dry, vacuum, microgravity environment. These processes likely include granular convection, landslide-like granular migrations, and particle sorting, result...
