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Oxygen in the Solar System


Oxygen in the Solar System Initiative: Origins of Isotopic
and Redox Complexity

Oxygen is the third most abundant element in the cosmos. Late in the last millennium, cosmochemists discovered that objects in the solar system not only show wide ranges in the isotopic composition of oxygen that are remnants of distinct nucleosynthetic histories, but also extreme variations in oxygen fugacity as evidenced in mineralogy and mineral chemistry. Yet, while these variations are well documented, an overarching model to explain their development in any combination of temporal and spatial coordinates is beyond our current grasp.

But our scientific reach should always exceed our grasp. The NASA Cosmochemistry Program and the Lunar and Planetary Institute are therefore sponsoring a five-year initiative (2003–2007) aimed at better understanding how these variations came to be, and what they tell us about the formation and evolution of the solar system. The Solar System Oxygen Initiative is absolutely not limited to that single element. Rather, the Initiative anticipates that wide ranges of topics need to be addressed in order to further our understanding of how oxygen isotopic and chemical variations were established in the solar system. Thus, (1) the nucleosynthetic origins of isotopically anomalous oxygen, (2) nebular variations in C/O, (3) core formation in planets of the inner solar system, and (4) the influence of cometary materials on the volatile element inventories of the terrestrial planets are all but a few of the topics to be considered. Addressing such a wide variety of topics will be difficult. Our intent, therefore, is to leverage the latent, inherent synergies of the NASA Cosmochemistry Program and also incorporate input from the international geoscience community.

The Solar System Oxygen Initiative has been divided into three teams, currently loosely defined as:

  • Terrestrial Planets – Accretion, planetary petrologic evolution, large-scale isotopic structures, redox state, core formation, and evolution of the hydrosphere.
  • Asteroids and Meteorites – Asteroid spectroscopy and surface modeling, dynamical scrambling of the belt, meteoritic evidence for parent body redox processes, and isotopic variations.
  • Oxygen in Earliest Solar System Materials and Processes – Nucleosynthesis, isotope reservoirs, solar nebula models, early sun and solar composition, interplanetary dust particles, cometary ices and dust, presolar grains, chondrite components (CAIs, chondrules, and matrices), outer planets, planetary atmospheres and satellite systems.

The teams have held workshops and convened special sessions at scheduled conferences with the intent of providing a focus for researchers interested in the topic, and a venue for them to present their ideas. Collaborations were encouraged, particularly interdisciplinary collaborations between teams. The Initiative will wrap up with publication of 2 books similar to the Basaltic Volcanism Study Project book (but smaller!) in which members of each team present the current understanding of “oxygen” in the solar system relative to their part of the Initiative.

For further information on the Solar System Oxygen Initiative in general, contact either Stephen Mackwell, Director, Lunar and Planetary Institute ([email protected]) or James J. Papike, University of New Mexico ([email protected]).

Oxygen in the Solar System Science Teams


Last updated
June 4, 2019