抖阴旅行射

On Dec. 3, 2020, an ascent vehicle belonging to China鈥檚 Chang鈥檈 5 space mission rose up from the surface of the moon, carrying just under 4 pounds of lunar rocks. Roughly two weeks and more than 200,000 miles later, they landed in Mongolia, marking the first time in 45 years that new moon rocks had returned to Earth.听

Carolyn Crow, a planetary scientist at the University of Colorado Boulder, has had a front row seat for the decades-in-the-making event. She鈥檚 part of a team of scientists from China, the United States, Europe and Australia that has taken the first-ever look at two confetti-sized pieces of those samples.听

The group Oct. 7 in the journal Science, providing new insights that could change the way humans look at the moon.听

At about 2 billion years old, the rocks are much younger than any that astronauts collected over six Apollo missions from 1969 to 1972. (The Soviet Union was the last country to return moon rocks to Earth during its robotic Luna 24 mission in 1976). The samples could help scientists fill a gap in the moon鈥檚 geologic record鈥攁 period after the lava that once flowed onto the surface of the moon stopped for good.听

The new rocks will also help scientists create a better timeline of when the moon was pummeled by asteroids and comets鈥攊nformation that can help reveal the geologic history of other planets.

鈥淭here are still many outstanding questions about the moon, and it鈥檚 really exciting to try to answer some of them,鈥� said Crow, an assistant professor in the Department of Geological Sciences.

New terrain

Crow isn鈥檛 new to moon rocks. In 2019, she joined a group that analyzed a collection that had sat untouched in storage since arriving on Earth in 1972 as part of the Apollo 17 mission.听

The Chang鈥檈 samples presented a thrilling new opportunity, she said.

鈥淚 had been sitting here in Colorado thinking it would be so awesome to work on these samples, and then I got an email asking me if I wanted to,鈥� she said. 鈥淥f course I did.鈥�

All of the roughly 800 pounds of rocks and dust that Apollo astronauts collected were 3 billion years old or older.听The Chang鈥檈 5 mission, however, traveled to a different part of the moon, home to the planet鈥檚 youngest basalt lava flows, more than 850 miles from the nearest American landing site.

There, you can find Mons R眉mker. This ancient volcano once erupted lava, creating rivers of molten rock that wove through trenches called 鈥渞illes.鈥� It was among the last places where lava leaked onto the lunar surface before the moon became the cold body it is today.

鈥淭hese samples fit into a region of time we don鈥檛 know anything about,鈥� Crow said.听

Just the beginning

The new rocks raise more questions than they answer.听

Scientists, for example, have long been puzzled about how the ancient moon cooled down. Lunar geologists believe that lava flows on the moon likely died off well before 2 billion years ago. But some regions, including around Mons R眉mker, seem to have become geologically active again, at least for a short period of time. One popular theory for that restart suggests that radioactive elements deep below the moon鈥檚 crust may have helped to turn up the heat in certain areas.

But, when Crow and her colleagues examined the Chang鈥檈 samples, they didn鈥檛 find a lot of those baking elements.

鈥淭here鈥檚 got to be something else that鈥檚 heating up the moon at this time,鈥� Crow said.听

The team鈥檚 analysis also suggests that asteroids and comets may have struck the moon鈥檚 surface at a lower rate than scientists once believed. That鈥檚 important, Crow said, because researchers use this rate to date the age of terrain听on the surface of Mars and other planets.

鈥淥ur research will cause a shift in what those ages are,鈥� she said. 鈥淭his has big implications for planetary science beyond the moon.鈥�
听
Over the next decade, NASA鈥檚 plans to send astronauts to new areas of the moon, including the icy stretches of the lunar south pole. Crow will be ready. She and her colleagues are working to acquire multi-million dollar equipment for 抖阴旅行射 Boulder so that scientists can conduct similar tests on lunar samples from Colorado鈥攎aking the university one of the rare institutions in the U.S. that would be a 鈥渙ne-stop shop鈥� for dating moon rocks.

听鈥淲e鈥檙e going to all new regions with all new records,鈥� Crow said. 鈥淭here鈥檚 still so much that we don鈥檛 understand.鈥�

Alexander Nemchin of Curtin University in Australia and Dunyi Liu of the Chinese Academy of Geological Sciences led the new research. Other coauthors included researchers from the Australian National University, University of Manchester, Brown University, Washington University, University of Notre Dame, Swedish Museum of Natural History and Planetary Science Institute.听