To paraphrase Rodney Dangerfield “Water don’t get no respect.” You drink it, you wash your car with it, you swim in it, but unless you are in the parched portion of the western U.S., you probably don’t think too deeply about water. Nevertheless, that simple combination of one oxygen and two hydrogen atoms is essential to life as we know it.
Water is Earth’s most abundant greenhouse gas and hence plays an important role in climate modulation. Water dissolved in minerals greatly decreases their strength and is perhaps a key ingredient that allows plate tectonics to operate on Earth. For these reasons, and many others, water is an important research topic at DTM, on which a number of breakthroughs have been made recently.
Collaborative work led by DTM’s Hubble Postdoctoral Fellow Jacqueline Faherty, using Carnegie’s Magellan Baade telescope at Las Campanas in Chile, accumulated enough photons emitted by a chilly, relatively nearby, brown dwarf to detect the presence of water ice clouds in its atmosphere, the first such detection outside our Solar System.
DTM staff scientist Conel Alexander was part of a team that explored whether water in the Solar System was completely destroyed and reassembled from its constituent atoms during the process of Sun and Solar System formation. The answer is no. A good portion of the water presently in the Solar System likely was water prior to the birth of the Sun. Previous work by Alexander documented the hydrogen isotopic similarity of water in primitive meteorites with that of Earth, implying that Earth’s water likely came with its planetary building blocks rather than added later, for example by comet impacts.
Work by DTM staff scientist Erik Hauri in collaboration with Alberto Saal of Brown University shows that Earth’s initial water need not have been lost during the violent collisions that accompanied Earth formation. They went to the least likely place to find water, the Moon, and by refining the detection limits for water using DTM’s ion probe, found water concentrations in lunar volcanic glasses that were not dramatically different from some lavas on Earth.
My own work with postdoctoral research associate Jonathan O’Neil, now a professor at the University of Ottawa, showed that 4.3 billion year old lavas in northern Quebec were erupted into bodies of liquid water, providing additional evidence that Earth’s surface, only a couple of hundred millions years after Earth’s birth, was already cool enough to support the presence of oceans or lakes.
Staff scientist Steve Shirey was part of a team that showed the presence of minerals included in diamonds from the deep mantle that contain high concentrations of water, which emphasizes the sizeable water storage capacity of Earth’s interior.
These discoveries showcase the strength of the multidisciplinary expertise at DTM to track water from outside our Solar System through the processes that formed our planet over four billion years ago. Next time you drink a glass of water, think about some of the interesting stories those water molecules might have to tell about the history of Earth and the Solar System.
Acting Director, Terrestrial Magnetism
Carnegie Institution for Science