Stardust aerogel with comet dust impact. The comet dust particle impacted into the aluminium frame holding the aerogel at bottom centre. Debris from the impact shot into the aerogel (blue), forming the explosion pattern seen. The aerogel was extended into the dusty coma of the comet Wild-2 by the Stardust spacecraft 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. The aerogel (blue) 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.