On the afternoon of February 10, 2009, the operational communications satellite Iridium 33 collided with the obsolete Cosmos 2251 communications satellite over Siberia at an altitude of roughly 800 kilometers. The collision was at a speed of 11.7 kilometers a second and produced a cloud of more than 2,000 pieces of debris larger than ten centimeters. This debris spread out over an extensive area within a few months and has been threatening to collide with other operational satellites since then. This event was a wake-up call for all satellite operators, but also for politicians. “The problem of so-called space debris—disused artificial objects in space—took on a new dimension,” says Professor Thomas Schildknecht, head of the Zimmerwald Observatory and deputy director of the Astronomical Institute at the University of Bern.

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