Ballistic panspermia, sometimes referred to as interplanetary panspermia, is a version of the panspermia hypothesis in which it is argued that impact-expelled rocks from a planet's surface serve as transfer vehicles for spreading biological material from one planet to another within the same solar system. It requires that the microorganisms survive (1) the impact ejection process from the planet of origin; (2) traveling through the solar system; (3) landing on a planet within the same solar system.