Tiny glass beads collected by NASA’s Apollo 17 astronauts are offering scientists fresh insights into the moon’s volcanic activity from billions of years ago. These surprising shimmering fragments, smaller than sand grains, were created when ancient lunar volcanoes expelled molten rock, which swiftly solidified into smooth glass in the frigid vacuum of space.

Utilizing contemporary tools that weren’t available half a century ago, researchers have meticulously studied the surfaces of the glass beads. They found a fine mineral powder, only visible under microscopes, that formed as the beads passed through gas clouds during eruptions.

A recent study published in the journal Icarus indicates that these surface coatings illustrate the evolution of the moon’s volcanic environment. The research spearheaded by Brown University uncovers a dynamic history of lunar volcanoes, marked by fluctuations in gas chemistry, temperature, and pressure.

“It’s akin to perusing the diary of an ancient lunar volcanologist,” commented Ryan Ogliore, a professor at Washington University in St. Louis.

The beads, expelled from the moon’s interior 3.3 to 3.6 billion years ago, cooled into smooth glass droplets. They display variations in color, shape, and chemical makeup, distinct from anything found on Earth, hinting at explosive eruptions akin to Hawaii’s fire fountains.

“The beads are minute, pristine capsules of the lunar interior,” Ogliore noted.

These fragile beads were protected from Earth’s air to avert contamination. Researchers concentrated on black glass beads from the Taurus-Littrow Valley, adjacent to the Sea of Serenity, formed following a significant impact on the moon.

The predominant mineral in the coatings was sphalerite, which consists of zinc, sulfur, and iron. The lower layers of the micro-buildup contained more iron, suggesting they formed earlier when conditions were hotter and denser. The upper sections formed later as temperatures decreased.

The black beads contained a greater abundance of zinc-and-sulfur minerals compared to orange beads from earlier samples, indicating thicker or hotter gas clouds during their formation.

To study the samples, the team employed a high-energy ion beam to disintegrate material, assessing its chemical composition. They also utilized advanced methodologies like atom probe tomography and electron microscopy.

“We’ve possessed these samples for 50 years, but now we have the technology to truly comprehend them,” Ogliore remarked. “Many of these tools would have been unfathomable at the time the beads were first gathered.”