The Open University ’ s repository of research publications and other research outputs Granular shear flow in varying gravitational environ

Despite their very low surface gravities, asteroids exhibit a number of different geological processes involving granular matter. Understanding the response of this granular material subject to external forces in microgravity conditions is vital to the design of a successful asteroid sub-surface sampling mechanism, and in the interpretation of the fascinating geology on an asteroid. We have designed and flown a Taylor-Couette shear cell to investigate granular flow due to rotational shear forces under the conditions of parabolic flight microgravity. The experiments occur under weak compression. First, we present the technical details of the experimental design with particular emphasis on how the equipment has been specifically designed for the parabolic flight environment. Then, we investigate how a steady state granular flow induced by rotational shear forces differs in varying gravitational environments. We find that the effect of constant shearing on the granular material, in a direction perpendicular to the effective acceleration, does not seem to be strongly influenced by gravity. This means that shear bands can form in the presence of a weak gravitational field just as on Earth. N. Murdoch Laboratoire Lagrange, UMR 7293, Université de Nice Sophia-Antipolis, CNRS, Observatoire de la Côte d’Azur, 06300 Nice, France and Planetary and Space Sciences, Department of Physical Sciences, The Open University, Milton Keynes, MK7 6AA E-mail: [email protected] B. Rozitis and S. F. Green Planetary and Space Sciences, Department of Physical Sciences, The Open University, Milton Keynes, MK7 6AA P. Michel Laboratoire Lagrange, UMR 7293, Université de Nice Sophia-Antipolis, CNRS, Observatoire de la Côte d’Azur, 06300 Nice, France W. Losert Institute for Physical Science and Technology, and Department of Physics, University of Maryland, College Park, MD 20742, USA E-mail: [email protected]