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The mission, named after the mythical Chinese goddess of the moon, brought the first fresh lunar samples in more than 40 years to Earth later this month.
The moon rocks collected by Chang’e-5 have been dated to 1.97 billion years old – relatively young, astronomically speaking, to the 4.5 billion year old moon. The objective of the mission was to recover rocks in the youngest areas of the lunar surface.
“This is the perfect sample to fill a 2 billion year gap,” said Brad Jolliff, study co-author and Scott Rudolph professor of Earth and Planetary Sciences in Arts and Sciences at the ‘University of Washington and director of the university’s McDonnell Center for the Space. Sciences, in a press release.
“All of the volcanic rocks collected by Apollo were over 3 billion years old,” he said. “And all of the young impact craters whose age has been determined from sample analysis are less than a billion years old. The Chang’e-5 samples therefore fill a critical gap.”
Rocks on the moon act as a time capsule for its history and evolution. Unlike the Earth, the Moon does not have tectonic plates or other processes that erase the existence of craters over time. Instead, these craters help scientists date different regions of the lunar surface.
Having a definitive date for Chang’e-5 rocks helps scientists better establish the chronology of events on the moon – and even provides a good model for dating craters on other rocky planets.
“Planetary scientists know that the more craters there are on a surface, the older it is; the fewer craters, the younger the surface. That’s a nice relative determination,” Jolliff said. “But to put absolute age dates on that, you have to have samples of those surfaces. The Apollo samples gave us a number of surfaces that we were able to date and correlate with the crater densities. crater chronology has been extended to other planets – – for example, for Mercury and Mars – to say that surfaces with a certain density of craters have a certain age. “
The composition of basalt, or dark, fine-grained volcanic rock, in the samples also shows that volcanic activity was still occurring on the moon about 2 billion years ago. The Chang’e-5 mission landed at Oceanus Procellarum, which is an area of solidified lava from an ancient volcanic eruption.
This means that there was probably once a heat source in the area to stimulate volcanic activity, but there is no evidence of this heat source. This means that researchers will need to explore other possibilities behind the activity.
“The task will now be to find a mechanism that will explain how this relatively recent warming of the Moon may have supported the formation of basaltic magmas with temperatures exceeding 1,000 degrees Celsius (1,832 degrees Fahrenheit) – and ultimately help researchers improve the dating the age of the entire solar system, ”said Gretchen Benedix, co-author of the study and professor at the Center for Space Science and Technology at Curtin University in Australia, in a statement.
China is targeting 2024 for its next moon landing with the Chang’e-6 mission, which will collect and return samples from the South Pole-Aitken basin on the far side of the Moon.
The research to understand all the secrets locked in the Chang’e 5 lunar samples is only just beginning, the researchers say. And the team leading this research is global, working together across the globe.
“The consortium includes members from China, Australia, US, UK and Sweden,” Jolliff said. “It’s science done in the ideal way: international collaboration, with free sharing of data and knowledge – and all done in the most collegial way possible. It’s diplomacy through science.”
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