A pair of geologically young craters, including one a mere 16 million years old, have been discovered in the darkest regions of the lunar surface, experts with the Southwest Research Institute (SwRI) reported in research to be published in the scientific journal Icarus.
In addition to the extremely fresh crater, a second believed to be between 75 million and 420 million years old were detected using the Lyman-Alpha Mapping Project (LAMP) instrument on board the Lunar Reconnaissance Orbiter (LRO), SwRI officials explained in a statement.
Using far-ultraviolet Lyman-alpha band skyglow and light from ultraviolet-bright stars, LAMP is capable of observing permanently shaded lunar regions. By combining those observations with data from the LRO’s Mini-RF radar, SwRI senior research scientist Dr. Kathleen Mandt and her colleagues were able to map the floors of large craters near the lunar south pole.
These craters are extremely difficult to study since sunlight never illuminates them directly, the researchers explained. Slight differences in albedo (reflectivity) measured by LAMP enabled the SwRI team to not only find the craters, which Dr. Mandt called “a really exciting discovery,” but also to estimate how old they were.
“Finding geologically young craters and honing in on their age helps us understand the collision history in the solar system,” she added. “Discovering these two craters and a new way to detect young craters in the most mysterious regions of the Moon is particularly exciting.”
Credit: NASA GSFC/SwRI
Technique could also be used on other planets and asteroids
Dr. Thomas Greathouse, LAMP deputy principal investigator with the SwRI, explained that the reason that researchers study planetary geology was to better understand the origins of the solar system. He said that it was “exciting and extremely gratifying” to find “a unique and unexpected new method for the detection and age determination of young craters.”
Dr. Mandt added that the new technique “will be useful not only on the Moon, but also on other interesting bodies, including Mercury, the dwarf planet Ceres, and the asteroid Vesta.” Collisions in space played a vital role in the formation of the moon and the rest of the solar system, she and her colleagues said, and impact craters can tell the story of those collisions.
The lunar surface is filled with such impact craters, they noted, and studying them could allow scientists to determine the motion of objects throughout the solar system’s history. Craters such as the two newly discovered ones, which are considered to be “young” based on a geological timeline, can also reveal information about how frequently collisions occurred.
Upon impact, an object causes material to be ejected and forms a ring of material that surrounds the crater. With younger craters, this ejected material is often comprised of rough rubble batches and a light coating of condensed, bright dust that, over time, become weathered and covered over by layers of darker, fluffier material.
In this case, the SwRI team determined that the areas surrounding these two newfound craters were brighter and rougher than the surrounding terrain. The older of the two craters had a rough extended ejecta blanket that had fades, suggesting that it had to be at least 75 million years old. However, the ejecta blanked was not completely covered in dark, fluffy dust, indicating that the crater was not yet 420 million years old.
—–
Image credit: Wikimedia Commons/NASA
Comments