But just because we have a lot of new moon rocks doesn’t mean we know everything about lunar geology. Many of our lunar samples come from the same relatively small area, says Jolliff, and even the ones that are farther apart are very similar to each other.
By REBECCA SOHN
The newest moon rocks to have landed on Earth are now headed to the lab.
On Dec. 17, the Chinese National Space Administration’s Chang’e 5 mission accomplished something no one has done in over 40 years — they brought a little piece of the moon to Earth.
That makes China the third country, along with the U.S. and the former Soviet Union, to bring back a sample from the moon, and the first since 1976, when the Soviet Union did so as part of their Luna 24 mission.
Scientists still have a lot of questions about the moon’s history, composition, and formation, and these new moon rocks could help provide some answers.
“I think of a sample collection like this as sort of like delivering us a treasure chest,” says Bradley Jolliff, a planetary scientist at Washington University in St. Louis.
A brief history of moon rocks
The first mission to sample the moon was also the first to land people on it — the Apollo 11 mission in 1969. Astronauts collected nearly 50 pounds of moon samples, and that was only the beginning.
The Apollo missions, which ran from 1961 to 1975, have brought over 800 pounds of lunar rock to Earth, teaching us about the moon’s history and composition. Scientists learned, for instance, that like the Earth, the moon has distinct layers — a crust, a mantle, and a core.
Scientists also saw that the moon and Earth are made of very similar types of rock, and were able to the formulate the current leading theory about how the moon formed: a Mars-sized object collided with the newly formed Earth, forming a cloud of debris that eventually became the moon.
But just because we have a lot of moon rocks doesn’t mean we know everything about lunar geology. Many of our lunar samples come from the same relatively small area, says Jolliff, and even the ones that are farther apart are very similar to each other.
“Imagine going to a place in the United States, picking up 100 kilograms of rocks, and then saying, tell me everything about the entire planet Earth,” says Christopher Edwards, a planetary scientist at Northern Arizona University. “It would be really hard and you would probably get a lot of stuff wrong.”
Many of the lunar rocks we have are incredibly old. The process of plate tectonics, in which the Earth’s hot, fluid mantle moves continents and eventually transforms much of Earth’s rock into magma, makes truly ancient rock a rarity here, says Jeremy Boyce, a planetary scientist at NASA’s Johnson Space Center who studies some of the Apollo samples.
But the moon, which has a completely cool and non-fluid mantle, does not have the same process. “On the moon, a lot of those rocks are still sitting there on the surface,” Boyce says of ancient rock samples. Many rocks on the moon are 3 to 4 billion years old, only slightly younger than our solar system.
Why the new rocks are so important
Until now, scientists haven’t been able to study the moon’s younger rock. The new samples from Chang’e 5 will change this. They’re from near Mons Rümker, a volcanic mountain where the rock is thought to be much younger — about 1 billion years old.
There are a lot of reasons scientists are eager to study this younger rock, one of which is that it could help us more precisely date not only the moon, but many rocky planets and other objects.
Here’s how that works: Scientists date lunar rock by using something called a chronology curve, says Jollliff. Essentially, they estimate the age of the rock by counting the number of craters in the area the rock comes from; those increase as objects impact the rock over time.
To make this estimation, scientists need to match the number of craters to a precise age. Right now, they only have data points for lunar rock that is 3 to 4 billion years old.
Modern techniques can date the new sample extremely accurately, and once scientists know its precise age, they can add a valuable data point to their chronology curve. The dating system will also help us more accurately estimate the age of all sorts of objects in space, like rocky planets and other moons.
Another reason scientists are keen to study this young volcanic rock is to find out more about how volcanism works on the moon. Jolliff says that it’s unclear why there was apparently volcanic activity on the moon for such a long period of time.
Most of the moon’s volcanic activity, he says, is thought to have occurred 3 or 4 billion years ago, when the moon was still pretty young.
But since the moon does not have plate tectonics, which drives volcanism on Earth, it’s unclear what could have caused much later volcanic activity. “That’s something that you can tease out of the samples by studying them in the lab,” Jolliff says.
The younger age and different chemistry of the new sample could aid in countless other areas of lunar research. Mark Loeffler, another planetary scientist at Northern Arizona University, studies the impact of radiation on the surface of the moon and on planets.
Over tens of millions of years, radiation from the sun causes the structure of rocks to deteriorate around the edges, giving it a characteristic rim. Based on his research, Loeffler has every reason to believe that this rim would also exist in the new sample, since it is over a billion years old.
But if it didn’t, it would totally upend that research, forcing scientists like Loeffler to reevaluate their ideas.
What else might we find out?
Other findings are all but impossible to foresee, says Juliane Gross, a planetary scientist at Rutgers University and NASA’s Deputy Curator of Apollo moon samples. “We might learn about other geological processes that operated in that region, processes that we might not even realize existed because they are not represented in the current sample collection,” she wrote in an email.
There’s also the matter of new technologies to analyze the samples. In the forty years since the last Luna mission, almost every conceivable tool for analyzing lunar rock has improved, and quite a few have been developed.
A notable example is X-ray computed tomography, which allows scientists to “see inside” pieces of rock without cutting them open or even touching them. The question isn’t what technology has evolved, says Boyce, but, “is there any technology that hasn’t evolved?”
Of course, the old samples haven’t gone away. Gross was recently one of three women who opened a sealed collection of Apollo samples, carefully preserved and untouched since they were first brought to Earth, so that future scientists might use new technology on pristine samples.
That same technology will allow scientists to learn more from these new samples much faster and more easily than in the past.
That said, “even if we did nothing but snap our fingers and double the size of the Apollo collection, we would learn new things,” says Boyce.
The moon rock waiting game
It might be a while before non-Chinese scientists learn anything about the Chang’e 5 samples, much less get to examine them. The Chinese National Space Administration (CNSA) has historically been quite secretive, and there are many details of the mission that most scientists outside China don’t know.
But Chinese scientists have said they will publish and share their findings, and Jolliff says that other nations, including the U.S., might be able to collaborate in research efforts focused on the samples in four to six months.
This mission will not be the only one to return to the moon. The CNSA has ambitious plans to eventually build a research base on the moon, and NASA is planning a return to human lunar landings by 2024 with its Artemis mission.
There are current and future lunar missions being conducted by many other countries, including Indian, Japanese, Russian, and South Korean space agencies.
When it comes to the moon, many people think “we’ve been there and done that, and learned everything there is to know about it,” says Jolliff. “And that’s just not the case.”
Originally published at Mashable Pakistan