New research shows that more than 4 billion years ago, the early lunar crust was rich in water; This contradicts a previously accepted assumption. Graduate student Tara Hayden, studying a lunar meteorite, discovered the mineral apatite (the most common phosphate) in a sample of early lunar crust.

“The discovery of apatite in the early lunar crust is extremely exciting because we can finally begin to understand this unknown phase of lunar history. We found that the early crust contained more water than we expected, and its volatile stable isotopes reveal a much more complex history than we previously knew. Lunar meteorites provide a fascinating new insight into lunar evolution.” “It reveals its fragments and expands our knowledge beyond the samples collected during the Apollo missions. I look forward to learning more about the far side of the moon as a new phase of lunar exploration begins,” said Hayden, who now works as an astrochemist.

New data points to an unexpectedly wet early lunar crust
A lunar meteorite sample studied by Tara Hayden. Source: Tara Hayden
After the Apollo moon samples were delivered, they were initially assumed to contain very little “volatile material”, leading to the moon being popularly described as “crazy dry”.

In 2008, Alberto Saal and other researchers discovered the presence of significant amounts of water and other volatiles in the Apollo sample collection. After fifteen years of reanalysis of samples, new moon meteorites revealed much more water on the moon’s surface.

“We know most about the history of water on the Moon from Apollo samples, but these samples are believed to represent only five percent of the moon’s entire surface. Until we get more samples from future Artemis missions, the only other surface samples we have are lunar meteorites,” Hayden said.

Hayden made the discovery while verifying the stone’s provenance for a collector. It turned out that the sample not only belonged to the Moon, but also contained valuable data about water.

“I was lucky that the meteorite not only came from the Moon, but most surprisingly, it had exactly the chemical composition that is important to our understanding of water-bearing minerals on the Moon,” Hayden said.

This study primarily focused on the apatite mineral, which contains volatile elements in its mineral structure. Apatite has been found in all types of lunar rocks except the first crust of the Moon. The ferroanorthuzite group is known to be very old (4.5-4.3 billion years old) and is the only type of rock that formed directly from the Lunar Magma Ocean when the Moon was almost completely molten. The discovery of apatite in such rocks made it possible for the first time to directly study this unknown stage in the development of the Moon.

“Uncovering the history of water in the early lunar crust, approximately 4.5 billion years ago, is important for improving our understanding of the origin of water in the Solar System. Ancient rock samples from the Moon in the form of lunar meteorites provide an excellent opportunity for such studies,” said Hayden Science. His man is Mahesh Anand.

Hayden says the timing of the discovery was perfect, as NASA’s Artemis missions were preparing to launch and researchers, including the chief science officer, were working to develop programs and goals for astronauts: “For a long time, the lunar surface was thought to be dry for the past thousands or even millions of years.” “But maybe there’s more water on the moon’s surface than we thought, and we need to find a way to get it out.”