New analysis reveals that the largest plain on the nearside of the moon, known as the Oceanus Procellarum, was not shaped by a giant impact crater, as many scientists believed, but rather by geological activity within the moon crust.
In a study published in Nature on October 1st, researchers analyzed data released by NASA’s Gravity Recovery and Interior Laboratory (GRAIL) mission and found that the flatland was probably formed by the stretching and thinning of the crust similar to tectonic movement on Earth (1).
New analysis reveals that the largest plain on the moon, previously thought to be a result of a large crater impact, was a result of the geological activity within the Moon’s crust.
Launched in 2011, the GRAIL consisted of a pair of probes that circulated the Moon at very low altitudes, taking careful measurements of their location and relative distance to each other (3). NASA used these measurements to create a detailed map of the Moon’s gravitational field that has given astronomers a deeper understanding of the Moon’s composition and clues to its past.
The map revealed valleys where the crust of the Moon has been stretched and thinned, only to be later filled in with lava flows.
The findings were unexpected, says Jeffrey Andrews-Hanna, a GRAIL co-investigator at the Colorado School of Mines who led the study. He noted that: “rift zones aren’t something known on the Moon, although we see them on Earth, Venus and Mars,” (2).
Hanna and colleagues explained that the regions around the Oceanus Procellarum have high concentrations of radioactive elements that serve to make the area hotter than its surroundings and allow it to cool more quickly. As the regions cooled and contracted, the crust at the edges stretched and thinned to from valleys in distinctive rectangular patterns, which could not have resulted from an asteroid impact (1).
“Our gravity data are opening up a new chapter of lunar history, during which the moon was a more dynamic place than suggested by the cratered landscape that is visible to the naked eye,” says Dr. Andrews-Hanna. He stressed that: “more work is needed to understand the cause of this newfound pattern of gravity anomalies, and the implications for the history of the moon.” (3)
Sources:
1. Andrews-Hanna, J. C., et al. (2014). Structure and Evolution of the Lunar Procellarum Region as Revealed by GRAIL Gravity Data. Nature, 514, 68-71. Retrieved October 6, 2014, from http://www.nature.com/nature/journal/v514/n7520/full/nature13697.html
2. Gibney, E. Moon’s Largest Plain Is Not an Impact Crater. Nature.com. Retrieved October 6, 2014, from http://www.nature.com/
3. NASA Mission Points to Origin of ‘Ocean of Storms’ on Earth’s Moon.. (2014, October 1). NASA. Retrieved October 6, 2014, from http://www.nasa.gov/