Recent analysis of lunar rock samples that were brought back from the Apollo 17 mission have revealed even more information regarding our moon’s evolution, specifically how long it took for it to completely cool down after forming.
Scientists studied a rock called “troctolite 76535” and what they found has changed previous theories regarding the evolution of the moon. It was previously believed that after the moon formed, it took approximately 100 million years to completely cool down. However, new studies have dramatically lessened that time frame to around 20 million years.
The experts chose the troctolite 76535 sample because it wouldn’t have been altered much while on the moon as explained by William Nelson who is a researcher at the University of Hawaiʻi at Mānoa, “It has not been strongly modified by impacts during its time on the moon's surface.” “Such pristinity is rare for lunar rocks.”
While measuring how much phosphorus was in the rock, the researchers also discovered other chemical variation patterns in the mineral grains, such as plagioclase and olivine. “This was unexpected, as previous studies had reported both of these minerals to lack any chemical variation,” Nelson told Space.com, adding that the variations found in the grains “could not have survived for as long as previously thought.”
In regards to the 20-million-year cooling period rather than the previous estimate of 100 million years, Nelson noted that “If the sample had cooled as slowly as previously suggested, then it should have no variations in P [phosphorus] content and that the variations would have been “ironed out” a very long time ago.
Even though it’s been nearly 50 years since the sample was collected, it is still revealing fascination information regarding the history of our moon, especially with help from new technology. “I believe quite a bit can still be learned from the Apollo sample collection,” Nelson said. “First and foremost, as demonstrated by this study, analytical techniques are always improving.” “Signals that were previously hidden because they were subtle can now be detected and leveraged in new ways.”
It’s incredible to think that this new study has changed the timeline of about 80 million years in regards to how long it took the moon to cool down and solidify. And with more lunar missions, additional samples will be brought back to Earth to be analyzed. We will surely find out even more fascinating information regarding our lunar companion. The study was published in the journal Nature Communications where it can be read in full.
A photo of the moon rock troctolite 76535 can be viewed here.