Oceans cover seventy percent of the Earth's surface is covered in water, and there's even more water trapped inside the Earth. Where did it all come from? And when? There have long been two possible answers to those questions: it could have been here since the very beginning, or it could have arrived later, carried by bombarding asteroids and comets.
The prevailing thought has been that the latter is more likely because, when the planets were forming nearly four and a half billion years ago, Earth's neck of the solar system would have been too hot for there to be water around.
But the either-or answers, the conjecture and lack of evidence have never sat well with Adam Sarafian, a graduate student in Geology and Geophysics at Woods Hole Oceanographic Institution. The question nagged at him until he decided to tackle it.
We know water as H2O - two hydrogens and an oxygen. But not all water is alike. Hydrogen can come in two forms, hydrogen or deuterium. Water from different places, times, and processes in the solar system have different ratios, or signatures, of hydrogen and deuterium.
What Sarafian set out to do was compare water on Earth to water trapped in chunks of rock from an asteroid known as Vesta. Vesta is special because it froze just fourteen million after the formation of the solar system. That means any water found in it was present in the inner solar system from the earliest days. If water on Earth looked like water from Vesta, that would suggest that Earth also had its water since the beginning.
But getting a sample of Vesta isn't easy. The American Museum of Natural History has such rocks, known as eucrites. But Sarafian was a young graduate student with a hard question and an unlikely hypothesis. He says it took some convincing, but he did finally get the samples he was after.
He also got an answer to his question which has shocked many. There is water in eucrites from Vesta, and it looks just like water on Earth. What's more, water from both Earth and Vesta looks just like water from another category of space rocks, called carbonaceous chondrites, which were some of the earliest meteorites to form.
Sarafian and his colleagues published this result in the prestigious journal Science in 2014, when Sarafian was just a second-year graduate student. But this isn't his first major accomplishment. He set pole-vaulting records in high school, and competed at the national level in college, despite a broken hand and two broken feet.
He's needed that kind of grit and persistence to get to where he is now. In elementary school, Sarafian found it difficult to read and was diagnosed with a learning disability. He found ways to compensate, but says academics wasn't his strong suit in high school and college. In order to pursue his passion for geology, he says he "locked himself away for a while" and figured out how to read scientific papers.
Today, Sarafian says he can skim a study or dive in deep and, either way, he finds it enjoyable. Fiction, though, remains a challenge - one he says typically isn't worth his time.
Note: This program originally aired January 11th on WCAI.
For more on Sarafian and his research: