Scientists are digging into the secrets of Moon dust to answer an age-old question: where did Earth’s water come from? For a long time, experts believed that water-rich meteorites crashing into the young Earth provided the primary source of our oceans. But new research led by Tony Gargano, a postdoctoral fellow at NASA, puts this theory to the test.
The team studied samples from the Apollo lunar missions. They used a technique that pinpointed water contributions from meteorites and found that the amount is much smaller than previously thought.
The Moon is like a time capsule, preserving the history of impacts in our solar system. Unlike Earth, the Moon’s surface isn’t constantly reshaped by weather or geological changes, making it an excellent record keeper. Gargano notes, “The lunar regolith is one of the rare places we can still interpret a time-integrated record of what was hitting Earth’s neighborhood for billions of years.”
By using a method called triple oxygen isotope analysis, which examines the most abundant element in rocks, the researchers could identify meteorite materials on the Moon’s surface. Astonishingly, only about 1% of the regolith was traced back to carbon-rich meteorites.
Recent findings published in the Proceedings of the National Academy of Sciences suggest that even under the best-case scenario, meteorites could only explain a tiny fraction of Earth’s ocean water. Justin Simon, a NASA planetary scientist, clarified, “Our results don’t say meteorites delivered no water; they suggest that late meteorite delivery is unlikely to be the main source.”
The study used known water content from carbonaceous meteorites, scaling these figures to estimate their potential contribution to Earth. Even with generous estimates, the volume was not enough to fill our oceans.
The Apollo missions, which collected lunar samples over fifty years ago, still play a vital role in scientific research today. Gargano remarks, “I’m part of the next generation of Apollo scientists — trained on the samples and the questions Apollo made possible.” Upcoming missions like Artemis III aim to explore new lunar terrains, potentially revealing even more about water sources in our early solar system. These areas, especially those in permanent shadow near the Moon’s poles, hold promise for further insight into this mystery.
These discoveries not only reshape our understanding of Earth’s water origins but also highlight the Moon’s ongoing significance in planetary science. With new missions on the horizon, who knows what other secrets the Moon may still hold?
