Lunar swirl tattoos on the moon surface are due to strong electric potentials, a new research has revealed.
The origins of the tangled lunar swirls observed by the Lunar Reconnaissance Orbiter (LRO), appearing almost finger-painted on the moon's surface, have been a mystery to scientists who have been studying it since its discovery. Past studies, however, gave the scientists several clues to its origin.
These swirls are noted to be present on areas where early traces of magnetic field are entrenched on the moon's crust. Due to the harsh space environment, minute meteorites, and solar wind, materials can chemically change and become darker. Researchers noted that the bright swirls are less windswept than the surrounding areas, however.
Some researchers theorized that the lunar tattoos are streaks left by ancient comets crashing onto the lunar surface creating wispy traces. Their light and dark streaks could also be due to the fine dust particles that swirl depending on their magnetic susceptibility. Scientists also postulated the lunar swirls may be due to a solar wind response to magnetic forces, which protected it from weathering.
Focusing on the magnetic shield theory, scientists developed computer models to test whether these lunar swirls are formed as a response to strong electric potentials caused by solar winds.
Bill Farrell, who leads DREAM-2 Center for Space Environments (Dynamic Response of the Environment at Asteroids, the Moon, and moons of Mars), seemed skeptical about the said theory because the moon's embedded magnetic fields are notably weaker, as much as 300 times than that of Earth. Farrell said that lunar surface would not have enough strength to deflect the electric charges of the solar wind.
But the new research concluded that when solar winds pass through, the moon's magnetic field produces a powerful electric field, which slows down and deflects solar wind particles. This reduces the harsh effect of the solar wind and bright swirl areas are produced.
The scientists, however, do not exclude the possibility of other theories.
"Until you have somebody making measurements on the lunar surface we may not get a definitive answer, but the new observations that analyze the swirls in ultraviolet and far-ultraviolet light are consistent with earlier observations that indicate the swirls are less weathered than their surroundings," said NASA project scientist John Keller.
Scientists involved in the DREAM-2 team want to test their hypothesis further by observing whether the lunar surface's magnetic shield will respond differently to varying solar wind strengths and directions. The researchers are also interested to develop a model of the processes of space weathering to help them understand how it affects the lunar surface.
Additionally, the LRO team is planning to improve the Lyman Alpha Mapping Project (LAMP) signal-to-noise ratio during dayside observations to enhance their study of the lunar swirls.
The study is published in three separate papers: Journal of Geophysical Research: Space Physics, Icarus, and Journal of Geophysical Research: Planets.