Old Water

Earth has a lot of water – over 70% of the planet is below sea level. Less than 3%  fresh water – almost all of that hiding as groundwater or frozen glaciers and ice-caps. Earth commands a orbital sweet spot around the sun – not too far, not too close, but just right to set us apart with liquid surface water. Water responsible for another unique distinction – plate tectonics. Water lubricates  continental plates, facilitating constant bump and grind across our molten outer core. Movement responsible for mountain ranges, weather patterns and life as we know it.

Not often pondered outside quality, supply and demand – our most basic element is taken for granted. Understanding frozen objects litter the universe doesn’t often translate to consideration of how we ended up with all that water.

A study led by Ilsedore Cleeves, an Astrochemist from the University of Michigan Ann Arbor, indicates much of our water was present before the sun formed – more importantly 30-50% of Earth’s water not only escaped heat,radiation, and vaporization when the sun booted up, some 4.6 billion years ago – it prevailed despite those conditions. When a star first “lights up”, the surrounding cosmic cloud (imagine a chaotic jumble of cosmic dust particles and ice) it’s subjected to intense heat and radiation – vaporizing ice, and separating some water molecules into oxygen and hydrogen.

Science could only speculate as to how much water survived this bombardment – in other words, what might have remained as a “universal ingredient” in planet formation. Of particular interest, the study of two very different waters – regular old water and heavy water. Heavy water contains an element called Deuterium or heavy hydrogen – Deuterium rich water (identified as having a hydrogen isotope containing  a neutron in addition to proton in the nucleus) is the product of substantial exposure to cosmic radiation.

Cleeves led researchers in creating a “planetary disk” – essentially a laboratory mock up of what happened to ice and water when the sun “lit” up. How much heat, direct solar radiation, and distance traveled by outside cosmic radiation were needed to account for measurable heavy water in our solar system.  Their conclusion, published Sept. 26 in the journal Science – water and heavy water didn’t add up. A whole lot of  water – perhaps as high as 50% came from icy interstellar space, millions of years before our sun got down to business.

“Our findings show that a significant fraction of our solar system’s water, the most-fundamental ingredient to fostering life, is older than the sun, which indicates that abundant, organic-rich interstellar ices should probably be found in all young planetary systems.” – Conel Alexander, research team member from the Carnegie Institute of Science.

Ponder that statement a moment – “abundant, organic-rich interstellar ices should probably be found in all young planetary systems” – that is so cool.