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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
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