Water covers about 71 percent of the Earth’s surface, but no one knows how or when such massive quantities of water arrived on Earth.
According to CTV News Canada, previous studies covering the origin of water on Earth suggested that melted meteorites “floating around” in space since the formation of the solar system four and a half billion years ago could be a reason.
However, new research published in the journal Nature on March 15, 2023, says meteorites have an “extremely low water content”. In fact, they are one of the driest extraterrestrial materials ever measured.
A team of researchers led by the University of Maryland, analyzed seven melted, stony meteorites that crashed into Earth billions of years ago. The team was able to pull fragments that showed these meteorites were pieces of planetesimals, which are objects that collided to form the planets in our solar system.
Because these meteorites fell to Earth only recently, this experiment was the first time anyone had ever measured their volatiles. UMD geology graduate student Liam Peterson used an electron microprobe to measure their levels of magnesium, iron, calcium, and silicon.
He then joined University of Maryland Assistant Professor of Geology Megan Newcombe, to measure their water contents with a secondary ion mass spectrometry instrument.
“We knew that plenty of outer solar system objects were differentiated, but it was sort of implicitly assumed that because they were from the outer solar system, they must also contain a lot of water,” said Sune Nielsen, a study co-author, and geologist at the Woods Hole Oceanographic Institution, reports Phys.org. “Our paper shows this is definitely not the case. As soon as meteorites melt, there is no remaining water.”
These results, which let researchers rule them out as the primary source of Earth’s water, could have important implications for the search for water—and life—on other planets. It also helps researchers understand the unlikely conditions that aligned to make Earth a habitable planet.
Newcombe said their findings have applications beyond geology. Scientists of many disciplines—and especially exoplanet researchers—are interested in the origin of Earth’s water because of its deep connections with life.
“Water is considered to be an ingredient for life to be able to flourish, so as we’re looking out into the universe and finding all of these exoplanets, we’re starting to work out which of those planetary systems could be potential hosts for life,” Newcombe said. “In order to be able to understand these other solar systems, we want to understand our own.”
