Presented By: Earth and Environmental Sciences
Smith Lecture: “Water” In and On the Surface of Terrestrial Planetary Bodies, by Any Means
Yang Liu, Jet Propulsion Laboratory
Searching for life in the solar system has been a continuing quest for planetary scientists. Water is the elixir of life, as we know, and as such, the central theme of space missions chasing after water in the solar system (e.g., Mars, Europa, Titan).
Our home planet is unique in the inner solar system for the presence of liquid surface water. It is only ~30 years ago that the Earth’s mantle was discovered to contain one ocean-worth water stored as OH in nominally anhydrous minerals (e.g., olivine, pyroxene). Despite these small relative abundances, water in the Earth’s mantle plays dramatic roles in many geological processes, from forming surface water through volcanic degassing to causing chemical and physical changes in the mantle. The search of water IN and ON the terrestrial bodies represents the logical extension of our knowledge of water on Earth.
Recently, our Moon has become the focus of such searches for water. The remote-sensed data has showed there is wide-spread “water” on the Moon (e.g., Pieters et al., 2009; Colaprete et al., 2011). However, it does not provide unambiguous ground-truth of water IN lunar soils. Toward this aspect, my colleagues and I have examined several Apollo lunar soils. Our results provide evidence for the first identification of OH in lunar soils that were derived from both solar-wind and non-solar-wind sources (Liu et al., 2012a), versus H in lunar volcanic glass. Proving solar-wind-formed water on the Moon is important in searching for water on other airless bodies in the solar system. The on-going missions to Mercury and 4 Vesta have actually observed minor amounts of water on these airless bodies, but are they similar to that on the Moon?
Mars, on the other hand, is the only other planet with clear signs of past/present liquid water. As such, “follow the water” has been the central focus of NASA’s martian exploration program. However, questions remain on when, where, and how water comes and goes on Mars. We recently recognized that impact melt pockets in martian meteorites record signatures of subsurface water, and thus provide an unique if not only tool to examine subsurface water reservoirs on Mars (Chen et al., 2015; Liu et al., 2018).
Here, I present results from my research on lunar and martian samples, and discuss future directions toward searching for water on the inner solar system bodies.
Our home planet is unique in the inner solar system for the presence of liquid surface water. It is only ~30 years ago that the Earth’s mantle was discovered to contain one ocean-worth water stored as OH in nominally anhydrous minerals (e.g., olivine, pyroxene). Despite these small relative abundances, water in the Earth’s mantle plays dramatic roles in many geological processes, from forming surface water through volcanic degassing to causing chemical and physical changes in the mantle. The search of water IN and ON the terrestrial bodies represents the logical extension of our knowledge of water on Earth.
Recently, our Moon has become the focus of such searches for water. The remote-sensed data has showed there is wide-spread “water” on the Moon (e.g., Pieters et al., 2009; Colaprete et al., 2011). However, it does not provide unambiguous ground-truth of water IN lunar soils. Toward this aspect, my colleagues and I have examined several Apollo lunar soils. Our results provide evidence for the first identification of OH in lunar soils that were derived from both solar-wind and non-solar-wind sources (Liu et al., 2012a), versus H in lunar volcanic glass. Proving solar-wind-formed water on the Moon is important in searching for water on other airless bodies in the solar system. The on-going missions to Mercury and 4 Vesta have actually observed minor amounts of water on these airless bodies, but are they similar to that on the Moon?
Mars, on the other hand, is the only other planet with clear signs of past/present liquid water. As such, “follow the water” has been the central focus of NASA’s martian exploration program. However, questions remain on when, where, and how water comes and goes on Mars. We recently recognized that impact melt pockets in martian meteorites record signatures of subsurface water, and thus provide an unique if not only tool to examine subsurface water reservoirs on Mars (Chen et al., 2015; Liu et al., 2018).
Here, I present results from my research on lunar and martian samples, and discuss future directions toward searching for water on the inner solar system bodies.
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