By Girish Linganna
Jun 3: A Chinese spacecraft successfully landed on the far side of the moon on June 2 to gather soil and rock samples. This mission aims to uncover differences between the less-explored far side and the more familiar near side of the moon.
The landing happened at 6:23 a.m. Beijing time (3.53 a.m India time) in a large crater called the South Pole-Aitken Basin, according to the China National Space Administration (CNSA).
The China National Space Administration (CNSA) has now achieved two successful landings on the far side of the moon. This recent landing follows the Chang'e 4 mission, which placed a lander-rover combination there in January 2019. No other country has managed even one landing on the moon's far side.
If everything goes as planned, Chang'e 6 will make further history for China. This mission aims to collect samples from the moon's far side and bring them back to Earth. This will give researchers their first close-up look at material from this part of the moon.
"The Chang'e-6 mission is the first to collect samples and return them from the far side of the moon," said CNSA officials in a translated statement. (Note: Chang'e 6 is a robotic mission, not a crewed one.) "This mission includes many engineering innovations and involves high risks and significant challenges."
Chang'e 6 launched on May 3 with a daring and unique mission: to bring back samples from the far side of the moon, the side that always faces away from Earth. (The moon is tidally locked to Earth, meaning it takes the same amount of time to rotate once on its axis as it does to orbit Earth. That's why we always see the same side of the moon from here.)
Why Do We Always See the Same Side of the Moon Even Though It Spins?: In simple terms, the Moon takes 27.3 days to complete one rotation, which is the same time it takes to complete one revolution around the Earth. Because of this, we always see the same side of the Moon from Earth.
Before Chang'e 4, all lunar missions focused on the near side of the moon because it's easier to explore. Communicating with robots on the far side is more challenging and usually requires special relay satellites. China launched these relay satellites before both the Chang'e 4 and Chang'e 6 missions. China's latest moon relay satellite, Queqiao-2, helped with the Chang'e 6 landing, according to CNSA officials.
Queqiao-2 Relays Signals : China’s Queqiao-2 communications relay satellite entered lunar orbit on March 24. It will serve as a communication link between Earth and lunar missions on the moon's far side, and will be used until at least 2030.
Queqiao-2 will orbit the moon and relay signals for the Chang'e-6 mission. The Chang'e-6 robotic probe aims to collect samples from an ancient basin on the moon's far side, marking the first time material from this hidden side will be brought back to Earth.
According to CNSA, Queqiao-2 entered its planned elliptical orbit on April 2 after performing a mid-course correction, near-moon braking, and orbital adjustments around the moon.
Chang'e 6 reached lunar orbit about four days after launch. It then spent a few weeks examining its planned landing site and preparing for June 2nd's main event. The landing went smoothly as planned: Chang'e 6's lander gently touched down in Apollo Crater, while the mission's orbiter, with its Earth-return module, continued to orbit the moon.
Adjustable Thrust Engine : The Chang'e-6 lander used an adjustable 7,500-newton thrust engine to reduce its speed in lunar orbit and start its descent.At about 2.5 kilometers above the lunar surface, the lander was set to quickly adjust its position before continuing its descent.The spacecraft paused about 100 meters above the surface to carefully avoid any hazards before landing.It used light detection and ranging (LiDAR) technology and optical cameras to identify a safe landing spot.
Chang’e-6 marks China’s fourth successful lunar landing out of four attempts and the second one on the far side of the moon. It is also the third lunar landing in 2024, following Japan’s SLIM in January and Intuitive Machines’ IM-1 Odysseus lander in February.
The lander will spend about 48 hours examining its surroundings and collecting around 4.4 pounds (2 kilograms) of lunar soil and rocks. Some samples will be taken from the surface, while others will be drilled from up to 6.5 feet (2 meters) underground using Chang'e 6's onboard drill.
Chang'e 6: Next Steps : After collecting samples, an ascent vehicle will launch from the Chang’e-6 lander with the samples. This launch is expected to occur about 48 hours after landing, taking the samples into lunar orbit. The ascent vehicle will then need to meet and dock with the Chang’e-6 orbiter waiting in orbit.
The samples will be placed in a reentry capsule for the trip back to Earth. The timing of the moon departure will be precise. The sample container will join the Chang'e 6 orbiter and start its journey back to Earth, landing with parachutes on June 25.The capsule will first bounce off the atmosphere and aim to land in the grasslands of Inner Mongolia. The samples will then be taken to special facilities for handling, analysis, and storage.
Chang’e-6 is part of China's larger lunar program. The country plans to follow it with two missions to the moon's south pole: Chang’e-7 in 2026 and Chang’e-8 around 2028. China also aims to launch its first crewed lunar mission by 2030.