Stardust aerogel with comet dust impact. Light micrograph of a section of aerogel from the Stardust spacecraft showing the track of a particle of captured comet dust (running bottom right to upper left). The aerogel collector on the Stardust spacecraft was extended into the dusty coma of the comet Wild-2 during its encounter in January 2004. The aerogel then returned to Earth in a capsule, landing on 15th January 2006. The spacecraft remained in space. Aerogel is a solid with extremely low density, designed to slow and stop the dust particles without damaging them. Comets are relics from the formation of the solar system, and study of their composition could provide information on its history. Magnification: x44 when printed 10cm wide.