Chang’e 6 | From the Moon’s far side Premium
The Hindu
Chang’e 6: China’s lunar exploration mission has returned soil and rock samples from the side of the moon that’s permanently facing away from the earth
On June 25, Chinese personnel picked up a 300-kg cannister from the Inner Mongolian Autonomous Region; it contained two fistfuls of soil and rocks. The event made international headlines because the cannister had started its journey on the moon’s far side — the side permanently facing away from the earth — and the soil and rocks it carried came from there, a place in the Solar System only Chinese robots have visited thus far.
The mission, called Chang’e 6 (named after a mythological moon goddess), was part of the Chinese lunar exploration programme and the country’s most important yet. A sample-return mission is more complicated than other types of robotic missions to the moon — including orbiters, landers, and rovers — because of the number of moving parts and stronger time constraints.
For Chang’e 6, the China National Space Administration (CNSA) sent a lander to the moon’s surface, like India did with the Vikram lander of Chandrayaan 3. There, a drill and scooper extracted some material samples from and just below the moon’s surface and deposited them in the cannister. The cannister was then placed in an ascender module that lifted off from the lander to orbit, where it rendezvoused with the orbiter. The cannister was here moved to a returner spacecraft. This spacecraft flew to within 5,000 km of the earth and ejected the cannister. The cannister finally made its way to the ground after a bounced atmospheric re-entry manoeuvre.
The lander landed on the moon’s far side, which doesn’t have line of sight from the earth, so no signal from the earth’s surface could reach it. The CNSA instead had ground stations communicate with the lander by sending signals to a satellite it had already installed in orbit around the moon. When this satellite came in view of the lander, it relayed the signals to the lander, collected the replies, and later beamed them to the earth. The mission lasted 53 days.
Once the capsule landed, officials flew it to the Chinese Academy of Space Technology in Beijing. There, experts of the Chinese Academy of Sciences would have taken the samples out and placed them in storage, in preparation for research and analysis. The world’s first mission to the moon’s far side was Chang’e 4, which in 2019 delivered a lander and a rover there. In Chang’e 5, the CNSA executed a sample-return mission from the near side, and followed it up with Chang’e 6.
Also read | China launches lunar probe mission to collect samples for first time from far side of moon
Various countries of the world have made ‘returning’ to the moon a priority of their respective national space programmes. Two vague leaders have emerged in this race: one led by the U.S. and the other by China. The U.S. is currently focusing on sending payloads built by private companies to the moon and on a major programme to regularly land humans on the moon from the early 2030s.