China's Chang'e-5 probe completed its second orbital correction in the moon-Earth transfer orbit Wednesday, according to the China National Space Administration.
Lunar rocks and soil collected by Chang'e 5 robotic mission will soon land on the snow-covered grasslands of Siziwang Banner in the Inner Mongolia autonomous region, the Jiuquan Satellite Launch Center, which governs the landing site, said.
All preparations have been made and personnel are ready to welcome the returning reentry capsule containing the precious samples, the center said in a statement on Tuesday afternoon.
A host of factors, including the reentry capsule's small size and its unique descending pattern, the thick snow and extremely low temperatures, as well as the fact that the vehicle is scheduled to touch down at night, will cause more difficulties than previous search and recovery operations, it said.
"The capsule's volume is about 14 percent that of our manned spaceship, but the area that it may land in is 16 times greater than that of previous manned missions," the center explained.
Recovery workers have performed several full-element exercises and have also thoroughly mapped the landing area.
Bian Hancheng, technical head of the recovery team from the center, said the reentry capsule was designed to adopt a special method to return to the ground. Because spacecraft flying back from the moon are traveling faster than those reentering from Earth orbit, the capsule will bounce off the atmosphere once to help it decelerate before making a final, fiery plunge to Earth.
This method is characterized by challenges to the capsule's flight control systems and a much larger landing area, he added.
Yu Dengyun, deputy chief designer of China's lunar exploration program, said the ultrafast speed during the reentry process will verify the probe's aerodynamic design, heat-resistant materials and flight control system.
Chang'e 5, China's largest and most sophisticated lunar probe, has four main components: an orbiter, lander, ascender and reentry capsule. The spacecraft was launched by a Long March 5 heavy-lift carrier rocket early on Nov 24 at the Wenchang Space Launch Center in Hainan province, setting out on the country's most challenging lunar adventure and the world's first mission since 1976 to bring lunar samples back to Earth.
Late on Dec 1, the lander-ascender combination landed on the moon, becoming the third spacecraft to touch down on the lunar surface this century after its predecessors－Chang'e 3 and 4. Shortly after landing, they began to fulfill their major tasks－to use a drill to obtain underground samples and then use a mechanical arm to scoop up surface soil. Samples were packed into a vacuum container inside the ascender.
The ascender lifted itself into an elliptical lunar orbit late on Dec 3. It rendezvoused and docked with the orbiter-reentry capsule combination early on Dec 6 and transferred the lunar samples into the capsule. The ascender separated from the combination later that day and was commanded to land on the moon on Dec 8.
The orbiter-reentry combination made two orbital injection operations over the weekend after traveling in a near-circular lunar orbit for nearly six days. After the injection maneuvers, the pair entered a moon-Earth transfer trajectory and began to fly back toward Earth.
(Sources: Xinhua and China Daily)