Sample Return Through the Ages
Jessica Barnes and Jemma Davidson– Guest Editors
Table of Contents
This thematic issue of Elements provides an overview of the mineralogical, petrological, and geochemical information learned about different planetary bodies through the study of extraterrestrial samples retrieved by both crewed and robotic missions. Sample return missions provide unique insights into the geological and chemical histories of a wide variety of celestial bodies, from the Sun and Moon to asteroids and planets. Each article—themed to a specific planetary body (e.g., the Moon, Mars) or series of bodies (e.g., asteroids, comets)—summarizes a previous mission or series of missions and their sample collection(s), and relevant current/future missions, and mission concepts. This issue focuses on the scientific benefits and discoveries gained or promised by sample return missions.
- To See a World in a Grain of Sand
- It’s Not Just a Phase: Over 50 Years of Lunar Sample Science
- Seeing Red: Retrieving Rocks from Mars and Phobos
- One’s Trash is Another’s Treasure: Cosmic Rubble Piles
- Space Weathering: Clear with a Chance of Solar Wind and Micrometeoroid Showers
- Ice to Meet You: Sampling Cold Bodies
THE VARISCAN OROGENY IN EUROPE – UNDERSTANDING SUPERCONTINENT FORMATION
Guest Editors: Urs Schaltegger (University of Geneva, Switzerland) and Karel Schulmann (University of Strasbourg, France; Czech Geological Survey, Czech Republic)
The Variscan orogen formed between 380 and 300 million years ago through several accretionary and collisional cycles, culminating with the construction of the Pangea supercontinent. This process occurred via sequential opening and closure of oceanic basins, synchronous detachment of Gondwana derived continental ribbons, and their outboard amalgamation onto the Laurussia margin. The Variscan orogen is rather unique compared with other orogenic belts on Earth: its overthickened and dominantly magmatic crust in the central belt, surprisingly minor mantle involvement in the magmatic and geodynamic processes, coherent and pulsed magmatism along the collision suture, and its complex accretionary history. Because its final product, Pangea, is the youngest and best-understood supercontinent on Earth, the Variscan orogeny offers clues for understanding the mechanisms of supercontinent formation.
- Variscan Orogeny: A Three Oceans Problem Karel Schulmann (Université de Strasbourg, France; Czech Geological Survey, Czech Republic), José-Ramón Martínez-Catalán (Universidad de Salamanca, Spain), and Urs Schaltegger (University of Geneva, Switzerland)
- Modeling the Variscan Orogeny Taras Gerya (ETH Zürich, Switzerland) and Petra Maierová (Czech Geological Survey, Czech Republic)
- Extent and Role of Cratonic Lithosphere in the Variscan Orogeny Stanislaw Mazur (Polish Academy of Sciences, Poland), Stephen Collett (Czech Geological Survey, Czech Republic), Imma Palomeras (Universidad de Salamanca, Spain), Christian Schiffer (Uppsala University, Sweden), and Olivier Vanderhaeghe (Université de Toulouse, France)
- Evolution and Structure of the European Variscan Lithospheric Mantle Lukáš Ackerman (Czech Academy of Sciences, Czech Republic), L. Gordon Medaris, Jr. (University of Wisconsin-Madison, USA), Andréa Tommasi (Université de Montpellier, France), and Alain Vauchez (Université de Montpellier, France)
- Granites and the Nature of the Variscan Crust Jean-François Moyen (Université Jean-Monnet, France), Alexandra Guy (Czech Geological Survey, Czech Republic), Patrizia Fiannacca (Università di Catania, Italy), Vojtech Janoušek (Czech Geological Survey, Czech Republic), Carlos Villaseca (Universidad Complutense de Madrid, Spain), and Puy Ayarza Arribas (Universidad de Salamanca, Spain)
- A Mantle Perspective on Variscan Lithosphere Evolution from Mountain Building to Collapse and Rifting Jacek Puziewicz (Univ. Wrocław, Poland), Sonja Aulbach (Goethe Univ., Germany), Olivier Vanderhaeghe (Paul Sabatier Univ., France), and Małgorzata Ziobro-Mikrut (Jagiellonian Univ., Poland)
- Assembling Pangaea – The Complex Morphology of the Laurussia-Gondwana Collision Brendan Murphy (St. Francis Xavier University, Canada), R. Damian Nance (Ohio University and Yale University, USA), Karel Schumann (Université de Strasbourg, France; Czech Geological Survey, Czech Republic), Yvette D. Kuiper (Colorado School of Mines, USA), and José R. Martínez Catalán (Universidad de Salamanca, Spain)
- Birth and Growth of Minerals from Aqueous Solutions (February 2025)
- Biomineral Geochemistry: Windows into Past Climates and Calcification (April 2025)
- Greenalite – A Tiny Crystal with a Big Story (June 2025)
- Re-Os – Clock With Clout (August 2025)
- Sample Return Through the Ages (October 2025)
- The Variscan Orogeny in Europe – Understanding Supercontinent Formation (December 2025)
Thematic Articles
In the 1960s and 1970s, NASA’s Apollo and the Soviet Union’s Luna missions captured imaginations across the world and revolutionized our under-standing of Earth’s moon and the Solar System. Over 50 years on, the realm of space exploration has expanded significantly, both in terms of the celestial bodies that have been explored and the nations working on these endeavors. In the coming decades, we will return samples from Mars and one of its moons, and humans will return to the Moon. This article sets the scene for this Elements issue, which will explore what we have learned about the formation and evolution of planetary bodies, including Earth, from analysis of returned samples, the links with orbital datasets, and priorities for the future.
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.
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.
Airless planetary surfaces are continually modified by energetic solar wind ions and hypervelocity dust impacts, a phenomenon known as space weathering. Models for space weathering are built on the foundation of returned sample analysis, but understanding these changes to surface regolith is also key to interpreting spacecraft remote sensing observations. Lunar samples first revealed the myriad microstructural and chemical effects of space weathering, and Genesis then provided important context for the mechanism of solar wind modifying these surfaces. Sample return from near-Earth asteroids has further transformed our understanding of how diverse bodies experience space weathering. The analysis of samples from these mineralogically diverse sources has contributed to a model for space weathering and planetary surface evolution across the Solar System.
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.