full moon
An image of one full side of the moon. NASA

Even though the first astronauts stepped on the moon nearly 50 years ago, researchers are still working to reveal the secrets of Earth’s only astronomical body orbiting Earth. More specifically, whether or not the moon once had or does have liquid water on it.

A study from the Scripps Institute at the University of California San Diego reveals that the moon is likely very to be dry inside with no liquid water, contrary to what a study published in June from Brown University argued.

The new results out of USC San Diego were thanks to the study of the “Rusty Rock” a rock that was returned to Earth after the Apollo 16 mission in 1972, according to USC. This rock is special because it appears to have rust on it, and rust of course needs water to form. The rock and the rust on it were both confirmed to have originated from the moon so neither could have come from elsewhere. This ruled out the option that water had come from elsewhere to cause the rust.

James Day, a geochemist and the lead author of the study published in Proceedings of the National Academy of Sciences, said the rock is a wet rock that comes from a dry part of the moon. He and his team determined this by conducting chemical analyses of the rock, reported USC.

“These rocks are the gifts that keep on giving because every time you use a new technique, these old rocks that were collected by Buzz Aldrin, Neil Armstrong, Charlie Duke, John Young, and the Apollo astronaut pioneers, you get these wonderful insights,” Day told USC, according to a press release.

These analyses revealed that the rust contained light isotopes of zinc, like that type that would probably be the result of condensing zinc due to the evaporation that occurred during the moon’s formation, according to the study. These zinc isotopes are also present in the lunar volcanic glass beads.

Zinc is a volatile element as are potassium, chlorine and water. When the moon formed, if it formed in a catastrophic formation, it may have depleted these volatile elements, says the study. If this is what happened then the moon’s interior would be full of these depleted isotopes and it would also be dry.

This research contradicts published research out of Brown University from June. That research was published as a study in Nature Geoscience as an analysis of glass deposits found on the moon and suggests that the moon actually has an abundance of water in its interior.

This contradiction opens a new area for research and further study of such isotopes found in the beads and in the rust on the rock. The difficulty is that it’s a challenge to discover where the rocks formed and how they did. A PhD student at USC is studying this now to get to the bottom of the composition of the various deposits.