The view from above in the furnace interior shows the glass beads which are produced by the Fraunhofer ISC and which are used for experiments in space research. Credit: © Fraunhofer ISC
How are asteroids and planets formed from stony particles? Fraunhofer researchers have developed beads made of a special type of glass. They form the composition of the rock particles as naturally as possible on a small scale. Earth is 4.57Byo. To understand how the blue planet was first formed long ago, scientists are analyzing fragments of asteroids etc that have arrived on Earth as meteorites after space collisions.
According to current knowledge, many planetary bodies were formed through the merger of chondrules – silicate beads 0.1 – 3 mm wide. In the study, special glass was used to form tiny beads to represent chondrules as realistically as possible. Previous findings indicate original particles had the consistency of hot, liquid glass before they aggregated into larger conglomerates of rock, cooled down and crystallized.
METHOD: 1. Rough glass gravel is prepared, sifted to the right size and then rounded out by thermal treatment. 2. Cut glass plates into small cubes and to grind them mechanically – very similar to the marble production. For the experiment, the researchers from Würzburg produced several versions of their beads, each of which differs slightly in material composition. These beads were first heated in special melting units in which the temperature and atmosphere can be adjusted precisely. Those beads with characteristics closest to the theoretical model after this test melting were selected for the project.
The research team from the Universities of Münster and Braunschweig now uses the cosmic glass beads from the ISC in experiments at the Center for Applied Space Technology and Microgravity (ZARM) in Bremen: The drop tower which is operated there surrounds a 120-high steel drop tube, in which a high-vacuum is kept. Through a catapult system, the glass beads are shot in a capsule to the tip of the drop tube. As a result, ~9.5s of weightlessness are achieved – the same conditions as in space. During this period, the glass beads are heated up to 1100 °C.
During the dropping procedure, the beads can collide and form larger clusters. The experts record the collision behavior with high-speed cameras that colleagues at TU Braunschweig assess. “Our colleagues from Münster then investigate how the beads merge, whether the clusters are composed of a homogeneous composition or whether the form of the individual beads is still recognizable, and whether and to what extent crystallization results,” Dr. Kilo explains. In the next step, the planetologists will compare the results with observations of meteorites to then draw conclusions about the validity of their theoretical models. http://www.fraunhofer.de/en/press/research-news/2016/january/cosmic-glasses-for-space-exploration.html
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