Alien Life Once Existed on the Moon, New Magnetic Field Discovery Suggests
If you think we've already learned all there is to know about the moon—think again. Though our moon does not possess a magnetic field, it once did, signaling that alien life may have existed there in the past.
Between 3.56 and 4.25 billion years ago, it ranged in strength from 20 to 100 microtesla, a unit that measures microflux density. Since the Earth is only 50 microtesla strong, they concluded that, at the height of its power, the moon's magnetic field was twice as strong as ours. By 3.19 billion years ago, prior research concluded it had already declined in intensity to less than 4 microtesla.
Though what happened after that is a mystery, researcher Sonia Tikoo and her team looked at an old moon rock collected in 1971 from the vast lava plain known as the "Sea of Rains." Dubbing the Apollo 15 sample 15498, they noticed that the sample was partially coated with melted glass, and as such, likely formed during a meteor impact on the moon's surface.
"Magnetic studies of lunar rocks indicate that the Moon generated a core dynamo with surface field intensities of ~20 to 110 μT between at least 4.25 and 3.56 billion years ago (Ga)," she wrote in the abstract of her study. "The field subsequently declined to <~4 μT by 3.19 Ga, but it has been unclear whether the dynamo had terminated by this time or just greatly weakened in intensity. We present analyses that demonstrate that the melt glass matrix of a young regolith breccia was magnetized in a ~5 ± 2 μT dynamo field at ~1 to ~2.5 Ga. These data extend the known lifetime of the lunar dynamo by at least 1 billion years."
Since a magnetic field is one of the requirements for a planet to support life, this extra billion years adds a whole new dimension to the question of whether or not there ever was a man on the moon.
Recently, a new study suggested that many of the moon's craters are in fact skylights, ancient lava tubes leading to a vast repository of ice below the lunar surface. Ice means water, and water means life. Coupled together, these discoveries put us ever closer toward discovering that our moon once possessed the ability to sustain life.
The paper goes onto explain that a protracted history such as this requires a substantial, long-lasting power source like core crystallization or precision. "No single dynamo mechanism proposed thus far can explain the strong fields inferred for the period before 3.56 Ga while also allowing the dynamo to persist in such a weakened state beyond ~2.5 Ga," it continues. "Therefore, our results suggest that the dynamo was powered by at least two distinct mechanisms operating during early and late lunar history."
Exactly when the lunar dynamo ceased remains unclear. Taking the likely geothermal properties of the moon into consideration, science has no explanation of dynamo scenarios powered by large impacts or purely thermal convection that could have predicted this magnetic field would have lasted for that long.
"We think that the early strong-field period may have been powered a relatively exotic mechanism—the Earth's gravitational pull on the lunar mantle may have mechanically churned the conducting fluid in the lunar core to drive the dynamo," Tikoo told Space.com. "We think this process could have generated enough energy to explain the strong field period."
"The late lunar dynamo field we inferred from this study was likely powered by slow solidification of the moon's core," she continued. "As the moon cooled off over time, the molten iron in the core began to solidify like water freezing to ice. This process can release thermal energy and cause hot, buoyant liquid metal to rise in the core like the fluid in a lava lamp. That combination of heat release and buoyancy-driven motion can prove the extra boost needed to power a long-lived magnetic field."
"The concept of a planetary magnetic field produced by moving liquid metal is an idea that is really only a few decades old," study co-author Benjamin Weiss said in a statement. "What powers this motion on Earth and other bodies, particularly on the moon, is not well-understood. We can figure this out by knowing the lifetime of the lunar dynamo."