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Studying shaken granular samples in microgravity

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On July 19, 2018, Alexander Gerst installed the Soft Matter Dynamics Experiment Container inside the Fluid Science Laboratory on board the International Space Station. The container was loaded with four CompGran sample units to study the dynamics of granular material under microgravity conditions. The B.USOC operators were commanding the payload and executed about 800 runs in 2018, during which various densities of spherical granules are shaken and their movement is observed through a technique known as dynamic light scattering. The result should improve the understanding of granular dynamics.
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After the refurbishment of the Columbus Fluid Science Laboratory (FSL) with a new video management unit, the Soft Matter Dynamics Experiment Container (SMD) has been installed and loaded with four Sample Cell Units of the CompGran experiment. The CompGran experiment aims to capture the diffusion of kinetic energy within the granular material using light scattering techniques allowed by the SMD optical diagnostics. The experiment has been designed by a collaboration of scientists under the coordination of Prof. Matthias Sperl (DLR).

Why in space?

On Earth, the study of the energy diffusion inside a shaken sample of granules is prevented by a quick sedimentation of the granules by gravity. The International Space Station offers a micro-gravity environment suitable to observe phenomena without the sedimentation interference, and this on a longer period than drop towers or parabolic flights. The CompGran experiment includes the observations up to 24 hours of the different shaken sample relaxation runs where the runs differ by the selection of granule material, size and density, and by the excitation process.

The Belgian User Support and Operation Centre as ESA Facility Responsible Centre for FSL and its payloads is in charge of all the operational phases of the experiment, from the reference runs on ground to the execution in space, in coordination with the scientists.

Video podcast of ESA astronaut Alexander Gerst about the Soft Matter Dynamics Experiment (.mp4). Credits ESA, October 2018.

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Soft Matter Dynamics Experiment Container loaded with one CompGran Sample Cell Unit during preparation tests in B.USOC Laboratory.
Credit: B.USOC/ADS/DLR/ESA