The essential role of planetary sample studies in exploration of the solar system has been well established “Drake et al., 1987”. As part of the larger pursuit of comparative planetology, samples of other rocky planets (Mercury, Venus, Mars), planetary satellites, asteroids, and comets should reveal much about the materials and processes that formed Earth. In that context, Mars is an especially appealing sample target because of its distinctive, Earth-like characteristics.

Here, we review the scientific objectives and justifications for collecting documented samples of Mars and returning them to Earth for laboratory study. A Mars sample-return mission will be technologically challenging but represents the only way to acquire definitive knowledge about formation of the planet, its geologic and climatic history, and its potential as a haven of life.