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When the Chang’e-4 mission landed within the Von Karman crater on January 3, 2019, China turned the primary and solely nation to land on the far facet of the moon — the facet that all the time faces away from Earth.
Now, China is sending one other mission to the far facet, and this time, its purpose is to return the primary samples of the moon’s “hidden facet” to Earth.
The Chang’e-6 mission, launched Friday, is ready to spend 53 days exploring the South Pole-Aitken basin to review its geology and topography in addition to gather samples from totally different spots throughout the crater.
The South Pole-Aitken basin is believed to be the largest and oldest crater on the moon, spanning practically 1 / 4 of the lunar floor with a diameter measuring roughly 1,550 miles (2,500 kilometers). The affect crater is greater than 5 miles (8 kilometers) deep.
Scientists hope that returning samples to Earth will assist reply enduring questions in regards to the intriguing far facet, which hasn’t been studied as deeply because the close to facet, in addition to confirming the moon’s origin.
“The far facet of the moon may be very totally different from the close to facet,” mentioned Li Chunlai, China Nationwide Area Administration deputy chief designer. “The far is mainly comprised of historic lunar crust and highlands, so there are plenty of scientific inquiries to be answered there.”
Throughout a NASA price range listening to on April 17, congressman David Trone requested NASA administrator Invoice Nelson why China was sending a mission to the “bottom” of the moon.
“They will have a lander on the far facet of the moon, which is the facet that’s all the time in darkish,” Nelson responded. “We’re not planning to go there.”
The moon’s hidden facet has typically been known as the “darkish facet of the moon,” largely in reference to the 1973 Pink Floyd album of the identical identify.
However the phrase is a little bit of a misnomer for a few causes, in keeping with consultants.
Whereas the far facet of the moon could appear darkish from our perspective, it experiences a lunar day and lunar night time similar to the close to facet, and receives loads of illumination. A lunar day lasts simply over 29 days, whereas the lunar night time lasts for about two weeks, in keeping with NASA.
The identical facet all the time faces Earth as a result of the moon takes the identical period of time to finish an orbit of Earth and rotate round its axis: about 27 days.
Moreover, the far facet of the moon has been harder to review, which led to the “darkish facet” nickname and created an aura.
“People all the time need to know what’s on the opposite facet of the mountain and the half you can’t see, in order that’s a type of psychological motivation,” mentioned Renu Malhotra, the Louise Foucar Marshall Science Analysis Professor and Regents Professor of Planetary Sciences on the College of Arizona in Tucson. “After all, we’ve despatched house probes which have orbited the moon, and we now have pictures, so in a way, it’s much less mysterious than earlier than.”
A number of spacecraft, together with NASA’s Lunar Reconnaissance Orbiter that continuously circles and takes pictures of the lunar floor, have helped to make clear the moon.
Yutu-2, a lunar rover that Chang’e-4 launched in 2019, additionally explored loose deposits of pulverized rock and mud littering the ground of Von Karman crater, positioned throughout the bigger South Pole-Aitken basin.
However returning samples to Earth would allow the most recent and most delicate know-how to investigate lunar rocks and mud, doubtlessly revealing how the moon got here to be and why its far facet is so totally different from the close to facet.
Regardless of years of orbital information and samples collected throughout six of the Apollo missions, scientists are nonetheless making an attempt to reply key questions in regards to the moon.
“The explanation the far facet is so compelling is as a result of it’s so totally different than the facet of the moon that we see, the close to facet,” mentioned Noah Petro, NASA venture scientist for each the Lunar Reconnaissance Orbiter and Artemis III, a mission which goals to land people on the moon for the primary time since 1972. “For all of human historical past, people have been capable of lookup and see the identical floor, the identical facet of the moon.”
However in 1959 the Soviet Union despatched a probe to fly previous the far facet of the moon and captured the primary pictures of it for humanity.
“We noticed this fully totally different hemisphere: not lined in massive volcanic lava flows, pockmarked with craters, a thicker crust. It simply tells a distinct story than the close to facet,” Petro mentioned.
Returning samples with robotic missions, and touchdown people close to the transition between the 2 lunar areas on the south pole by way of the Artemis program, “will assist inform this extra full story of lunar historical past that we’re missing in proper now,” he mentioned.
Though scientists perceive why one facet of the moon all the time faces Earth, they don’t know why that individual facet completely faces our planet. However it may have one thing to do with the moon being asymmetrical, Malhotra mentioned.
“There’s some asymmetry between the facet that’s going through us and the opposite facet,” she mentioned. “What precisely brought about these asymmetries? What truly are these asymmetries? We have now little understanding of that. That’s an enormous scientific query.”
Orbital information has additionally revealed that the close to facet has a thinner crust and extra volcanic deposits, however solutions to why that’s has eluded researchers, mentioned Brett Denevi, a planetary geologist on the Johns Hopkins College’s Utilized Physics Lab.
“It has a distinct type of geochemical composition with some bizarre additional heat-producing components. There are a ton of fashions for why the close to facet is totally different than the far facet, however we don’t have the info but,” Denevi mentioned. “So going to the far facet, getting samples and doing totally different sorts of geophysical measurements is de facto necessary to determining this actually lengthy, lengthy standing thriller.”
Chang’e-6 is only one mission heading to the moon’s far facet as NASA has plans to ship robotic missions there as properly.
Denevi helped design a mission idea for a lunar rover known as Endurance, which is able to undertake an extended drive throughout the South Pole-Aitken basin to gather information and samples earlier than delivering them to the Artemis touchdown websites close to the lunar south pole. Then, astronauts can examine the samples and decide which of them to return to Earth.
One of the vital basic questions that scientists have tried to reply is how the moon fashioned. The prevailing idea is that some type of object had an affect with Earth early in its historical past, and a large chunk that went flying off our planet fashioned the moon.
Scientists additionally need to understand how the moon’s authentic crust fashioned.
Volcanic flows created darkish patches on the moon, whereas the lighter elements of the floor symbolize the moon’s primordial crust.
“We predict at one level the moon was completely molten, and it was this ocean of magma, and as that solidified, minerals floated to the highest of this ocean, and that’s that lighter terrain that we are able to see in the present day,” Denevi mentioned. “Attending to the actually huge expanses of pristine terrain on the far facet is simply one of many objectives.”
In the meantime, the examine of affect craters littering the lunar floor supplies a historical past of how issues moved round throughout the photo voltaic system’s early days at a important level when life was beginning to kind on Earth, Denevi mentioned.
“As impacts had been occurring on the moon, impacts had been occurring on the Earth on the similar time,” Petro mentioned. “And so each time we take a look at these historic occasions on the moon, we’re studying just a little bit about what’s occurring on the Earth as properly.”
Visiting the South Pole-Aitken basin could possibly be the beginning of fixing a large number of lunar mysteries, Malhotra mentioned. Whereas researchers imagine they’ve an thought of when the crater fashioned, maybe 4.3 billion to 4.4 billion years in the past, amassing rock samples may present a definitive age.
“Many scientists are positive that if we found out the age of that melancholy,” she mentioned, “it’s going to unlock all types of mysteries in regards to the historical past of the moon.”
CNN’s Wayne Chang contributed to this report.