Moon rocks brought to Earth by Chinese mission fill key gaps in history
China’s new Moon-rock treasure trove may be a billion years younger than the material the Apollo program brought home decades ago. In December, China’s Chang’e 5 spacecraft managed to return
1.73 kilograms of Moon rock from a region called Oceanus Procellarum to scientists on Earth. Since then, scientists with access to the precious material have begun a bevy of experiments to understand the rocks and the secrets of the Solar System that they might hold.
The spacecraft seems to have snagged the perfect sample to fill a critical hole in scientists’ knowledge: two tiny pieces have been dated to about 1.97 billion years old, give or take 50 million years. “It’s the perfect sample to close a 2-billionyear gap,” said Brad Jolliff, a planetary scientist at Washington University in St. Louis in Missouri.
Scientists hoping to untangle the 4.5-billion-year history of the Solar System have combined those time-stamped samples with a technique to identify relative ages called crater dating. “Planetary scientists know that the more craters on a surface, the older it is, and the fewer craters, the younger the surface,” said Jolliff. “But to put absolute age dates on that, you have to have samples from those surfaces.” The age of the samples is also important because they are a type of rock called basalt, which forms during volcanic eruptions. Scientists previously only had evidence of lava flowing on the Moon up until about 3 billion years ago.