China's Lunar Lander Found a New Kind of Moon Rock
The first lunar rover in more than 40 years has uncovered a new type of moon rock.
A team of geologists and planetary scientists behind the recent Chinese Chang'e-3 moon mission just announced the discovery of a never-before-seen type of basalt on the moon. The team, led by Zongcheng Ling-an astronomer at Shandong University in Weihai, China-identified the rock using a pair of optical spectrometers on board the mission's Yutu lunar rover. The new discovery is published in Nature Communications.
"I think it's fair to say we really don't understand the moon nearly as well as many people may think."
In December 2013, the Chinese rover was the first vehicle to stroll across our moon's surface since U.S. astronauts last walked there in 1972. The vehicle lost mobility after about one month, but during that time its suite of science tools captured data well beyond the capabilities of early 70's Apollo technology. "Now after more than 40 years, we finally have new ground truth," that is, direct on-the-ground observations, "of a new landing site on the moon," Ling says.
Lunar Mysteries
The new find is a type of basalt, a volcanic rock formed by cooling lava flows and rich in silica minerals. At about 2.96 billion years old, the rock is the youngest identified to date. (Keep in mind, scientists think the moon is about 4.5 billion years old.) Unlike other samples taken across the lunar landscape during NASA's Apollo missions or the even-earlier Soviet Luna program, this new basalt has unusually rich quantities of iron, titanium, and an olive-green mineral called olivine. That's important, Ling says, because this interesting composition may help us unlock the mystery of moon's formation and cooling.
You can see the part of the moon where the Yutu rover identified this new type of rock if you look into a clear moonlit sky (From the Northern Hemisphere.) If the moon were a watch face, look at about 11 o'clock to find a large circular dark spot called Mare Imbrium. Now peer towards the northernmost edge of that dark circle-that's where the Yutu rover sits among these basalt rocks, slowly gathering dust.
"Now after more than 40 years, we finally have new ground truth."
Thomas Watters, a planetary scientist with the Smithsonian Institution and NASA's Lunar Reconnaissance Orbiter, notes that humanity has explored precious little of the moon's surface. Therefore, he says, "it's not terribly surprising that [Ling and his colleagues] found a type of basalt that had not been seen or sampled before-but I think it's nonetheless significant. This type of find improves the picture we can paint of the moon's evolutionary history. The moon still has a lot of surprises. I think it's fair to say we really don't understand the moon nearly as well as many people may think. Maybe even less than we thought we did just 10 years ago."
Where It Came From
Easily the biggest remaining lunar mystery is tied up in how, exactly, the moon formed. Today most scientists believe the moon was created 4.5 billion years ago when our own proto-planet collided with another rocky planetoid the size of Mars-mixing the two planets together and hurling a chunk into orbit where it cooled into the Moon we see today. But the story splits at this point. Some scientists think the heat of this impact liquified the entire moon into what was basically an enormous ball of magma. Others think that the impact wasn't quite as energy-intense, and gave the moon just a partial lava ocean. Because our Moon's origin is so inextricably tied to our own planet's history, figuring out which of these two paths is the truth will help scientists to better understand how Earth cooled and formed in the aftermath, Watters says.
This is exactly the kind of question the Yutu rover's new rock will illuminate, says Ling. The new basalt is not only a snapshot into an never-before-studied segment of the moon's volcanic past, but it also may reveal interesting dynamics of the shifting magma flows that were happening below the moon's mantle at the time. That's because right now, the scientists believe the new basalt rock is "a rock mixture formed from two different sources that combined and hybridized," says Ling.
For now, Ling says, it's off to the laboratory with this new rock data to see what it can reveal about the past.
