The Water in Your Body Is 4 5 Billion Years Old

The Water in Your Body Is 4 5 Billion Years Old The water moving through your body right now is older than the Sun it orbits. It began as ice in the cold dark of space, long before our star first caught light, and tonight we follow it home. Settle in, let your breathing slow, and let the story carry you. By every ordinary rule of how planets form, Earth should have been born dry. It came together close to a young, radiation-heavy Sun, in a region far too hot for water to survive, and yet it became a blue world, with more than half of your own body made of water on quiet loan from its oceans. This episode traces the long, patient hunt for where that water came from, and how much of it turns out to be older than anyone expected. We begin inside the body and work outward. We look at Mars, the neighbor that had rivers and lakes and slowly lost almost all of them. We learn to read the chemical fingerprint hidden in every drop of water, the ratio of heavy hydrogen to ordinary hydrogen that records where and when it formed. Then we follow that fingerprint through the case, one calm suspect at a time. The water-bearing meteorite that fell on a Sunday morning in Australia. The comets that seemed the obvious answer, until a spacecraft tasted one and found it did not match. The migrations of the giant planets, and Jupiter's grand detour that swept water-rich rocks toward the young Earth. The pristine asteroid sample carried home to a desert. The surprising discovery that the Sun itself makes a little water. The ancient crystal that pushed Earth's first oceans back almost to the beginning. And finally the deepest layer of all, the interstellar ice that predates the Sun. Sleep well. We will drift together again another night. Sources and further reading Wilde, Valley, Peck and Graham (2001). Evidence for liquid water and a cool early Earth from a 4.4-billion-year-old detrital zircon, Jack Hills, Western Australia. Nature. Gomes, Levison, Tsiganis and Morbidelli (2005). Origin of the cataclysmic Late Heavy Bombardment period of the terrestrial planets, and the migration of the giant planets. Nature. Known collectively as the Nice model. Walsh, Morbidelli, Raymond, O'Brien and Mandell (2011). A low mass for Mars from Jupiter's early gas-driven migration. Nature. The Grand Tack hypothesis. Altwegg et al. (2015). Rosetta ROSINA measurement of the deuterium-to-hydrogen ratio of comet 67P/Churyumov-Gerasimenko, roughly three times Earth's ocean value. Science. Hartogh et al. (2011). Ocean-like water in the Jupiter-family comet 103P/Hartley 2, for context in the comet debate. Nature. Genda and colleagues (mid-2000s). Modeling of magmatic degassing and the volume of Earth's early ocean. Daly et al. (2021). Solar wind contributions to Earth's oceans, based on atom-probe tomography of grains from asteroid Itokawa. Nature Astronomy. Ryugu sample return analyses (2022 to 2023). Hydrogen isotope and hydrated-mineral measurements from the Hayabusa2 initial analysis teams. Drabon and colleagues (2021), building on earlier modeling by Norman Sleep and others (from 1989 onward). Evidence and models for large early impacts capable of vaporizing the early ocean. University of Copenhagen (2023). Work on the multiple isotopic components of Earth's water inventory, including a share inherited as interstellar ice. Zellner (2017), Cataclysm No More, and related re-analyses questioning a sharp Late Heavy Bombardment spike. Missions and observatories Apollo (NASA, 1969 to 1972). Returned lunar samples used to date the impact record. Hayabusa (JAXA). Returned the first grains of asteroid Itokawa in 2010. Hayabusa2 (JAXA). Launched December 2014, returned samples of asteroid Ryugu to South Australia in December 2020. Rosetta and the ROSINA instrument (ESA). Orbited comet 67P/Churyumov-Gerasimenko from 2014. Mars Express and the MARSIS radar (ESA). Reported radar reflections beneath the Martian south polar cap in 2018 (Orosei and colleagues). The liquid-water interpretation remains debated. Cassini-Huygens (NASA, ESA, ASI, 2004 to 2017). Sampled the Enceladus plumes and studied Titan. Galileo (NASA). Evidence for subsurface oceans on Europa, Ganymede and Callisto. New Horizons (NASA, 2015). Data consistent with a possible subsurface ocean on Pluto. MESSENGER (NASA). Confirmed water ice in permanently shadowed polar craters on Mercury. Hubble Space Telescope (NASA, ESA) and the James Webb Space Telescope (NASA, ESA, CSA). Water vapor in exoplanet atmospheres such as K2-18b, and water ice and vapor in protoplanetary disks around newborn stars. Subscribe To: ‪@the_cosmicdrift‬