Thematic Articles

Icy materials are dispersed throughout the Solar System, from the planets, to their moons, and to asteroids and comets. The volatiles contained within these icy reservoirs could provide vital insights into the origin and evolution of their parent bodies, as well as details of conditions in the early Solar System. Development of the technologies needed for volatile sample return missions has therefore been given a high priority for the current decade. In this chapter, we describe volatile materials and ices in the Solar System, with a focus on comets. We summarize the history of cometary exploration, describe the results of NASA’s Stardust mission to comet 81P/Wild 2, and discuss the future of comet sample return.

Until 15 years ago, meteorites and cosmic dust were the only extraterrestrial materials available for investigating the nature and chemical evolution of the early Solar System. Since then, three major sample return missions have significantly advanced our understanding of the material composing the small bodies that populate our Solar System. The asteroid sample return mission Hayabusa first proved the direct link between an asteroid type and the most common type of meteorites falling to Earth. The Hayabusa2 and OSIRIS-REx missions recently collected and returned material from two carbonaceous asteroids, Ryugu and Bennu, respectively. Together, the results from those samples are revealing information not gleaned from studies of meteorites and are revolutionizing our understanding of the formation and evolution of planetary bodies at the dawn of our Solar System.

Mars Sample Return (MSR) missions have been a priority for the planetary community for decades. The NASA Perseverance rover mission is collecting diverse samples from Mars for potential return to Earth, whereas the JAXA Martian Moons eXploration (MMX) mission will bring back samples from Phobos, the largest of Mars’ two moons. High-resolution analyses of these samples in Earth-based laboratories will enable us to answer key questions that current martian data (meteorites, rovers, and orbiters) are unable to fully address. MSR results will better inform our understanding of the geological and planetary evolution of the red planet, the possibility of habitability and life on Mars, the potential for human exploration, and the formation of its moons and the martian system.

Landed robots, rovers, and orbital spacecraft provide regional-scale information about the nature of the Moon’s surface, but such data require ground truth information made accessible through lunar samples. Such samples include a range of material including hand-specimen-sized rocks, pieces of rocks chipped from boulders by astronauts wielding geologic hammers, to soil—scooped, trenched, and drilled from the upper few meters of the Moon’s surface by robots as well as humans. This chapter provides an overview of recent discoveries made using the lunar sample collection, highlights outstanding questions about the Moon’s origin and evolution, and discusses how these knowledge gaps will be addressed by future sample return missions.