Things got dicey yesterday aboard the International Space Station (ISS). Late in the day, Russian cosmonauts Sergey Prokopyev and Dmitry Petelin were preparing for a spacewalk when exterior cameras showed a stream of white flakes pouring from the Soyuz spacecraft attached to the station. Simultaneously, telemetry indicated a drop in pressure in the Soyuz’s coolant tank, indicating that it was the source of the leak.