Determining which fuels fed the Moon’s flame-fountains
During the Apollo 15 and Apollo 17 missions to the Moon, astronauts collected glass beads found on the satellite’s surface. While ‘Moon Glass’ necklaces would surely make lovely keepsakes, the real motivation was to analyze the glass to determine how it ended up on the inert surface of the Moon. The answer appears to be nothing less than fountains of flame and magma, and raises questions about the origins of the Moon and its geology.
The eruptions in question were likely the result of jets of basaltic lava bursting through a vent on the Moon’s surface. Rather than ooze out of the fissure, lava would have splattered, with the small droplets cooling quickly to form glass beads. This happens on Earth as well, but the gases driving the initial jet is likely different. Earthbound fire-jets are usually pressurized carbon dioxide or water, whereas these lunar fire-jets were probably filled with carbon monoxide.
The exact gas that powered the fountains is hard to prove, but by analyzing what the glass is made of, scientists have been narrowing the possible candidates. It’s important to determine, because knowing what possible volatile substances were present on the Moon will help us understand its creation. The Moon is thought to have been formed by an Mars-sized object breaking a piece off the Earth. Such a violent event makes it slightly counter-intuitive that volatiles, compounds with relatively low boiling points, would survive that encounter. The fire-fountains that created the Moon glass indicate that some volatiles were present, and the question is now to determine if they truly originated from Earth or if they were somehow deposited later in the Moon’s history.
Source: Carbon Monoxide 'Fire Fountains' Erupted on the Moon by Irene Klotz, Discovery News