China's most sophisticated and challenging space adventure – the Chang'e 5 robotic lunar mission – ended successfully early Thursday morning with its load of rocks and dust from the moon landing on the grasslands in northern China.
The China National Space Administration said in a statement that Chang'e 5's reentry capsule touched down on its preset landing site in Siziwang banner of the Inner Mongolia autonomous region at 1:59 am.
The recovery team will make initial processing of the capsule and then use a plane to transport it to Beijing where it will be opened for technicians to remove the container holding lunar samples, the administration said.
The re-entry and landing started around 1 am when mission controllers uploaded high-accuracy navigation data to the orbiter-reentry capsule combination that was traveling around the Earth.
The capsule then separated from the orbiter about 5,000 kilometers above the southern Atlantic Ocean and began to descend toward Earth. It entered the atmosphere at the second cosmic velocity, or 11.2 kilometers per second at 1:33 am, and soon bounced off the atmosphere to further slow down its ultrafast speed that could cause damage to the vehicle. Later, the craft reentered the atmosphere at a much slower speed of about 7.9 km per second, also known as the first cosmic velocity.
When the module was about 10 km above the ground, it released its parachutes and smoothly landed on the snow-covered grasslands. Recovery personnel sent from the Jiuquan Satellite Launch Center soon came to the landing site in helicopters and off-road vehicles.
The successful landing marked the completion of the historic 23-day Chang'e 5 expedition, the first in more than 40 years, to bring lunar samples back to Earth, also making China the third country to achieve this feat after the United States and the former Soviet Union.
Next, the sealed samples will be transferred to specially designed laboratories for analyses, experiments and tests so scientists can determine the extraterrestrial substances' composition, structure and traits, thus deepening their knowledge about the history of the moon and the solar system.
A certain proportion of the samples will also be on public display to enhance science awareness among the public, especially young generations, sources close to the mission have said.
Chang'e 5, China's largest and most advanced lunar probe, consisted of 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 South China's Hainan province, setting out on China's most difficult space activity and the world's first lunar sample-return mission since 1976.
The probe separated into two parts -- the orbiter-reentry capsule combination and the lander-ascender combination -- while in lunar orbit early on the morning of Nov 30.
Late on Dec 1, the lander-ascender combination landed on the moon, becoming the world's third spacecraft to touch down on the lunar surface this century after its predecessors – Chang'e 3 and 4.
The landing site was near Mons Ruemker, an isolated volcanic formation located in the Oceanus Procellarum, or Ocean of Storms, a vast lunar mare on the western edge of the moon's near side. The area had never been visited before Chang'e 5 mission.
Shortly after landing, the combination began to fulfill its major tasks – to use a drill to obtain 500 grams of underground samples and then use a mechanical arm to scoop up 1.5 kg of surface dust. Samples were packed into a vacuum container inside the ascender. The lander also unfurled the first free-standing Chinese national flag on the moon.
The ascender activated an engine late on Dec 3 to lift itself into an elliptical lunar orbit to prepare for docking with the reentry capsule, marking the first time a Chinese spacecraft has blasted off from an extraterrestrial body.
It rendezvoused and docked with the orbiting combination early on Dec 6 and transferred lunar samples into the reentry capsule. The ascender separated from the combination later that day and was commanded to impact on the moon on Dec 8.
The 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 on Sunday and began to fly back toward Earth.
According to the space administration, the Chang'e 5 mission was designated to fulfill several objectives. In terms of space engineering, it should demonstrate and verify technical plans and apparatus for autonomous lunar sampling and packing, moon-based launching as well as lunar orbital docking. In the scientific context, it was tasked with investigating the landing site's geological and topographic features, and enabling scientists to analyze lunar samples' structure and physical traits so they can deepen their research into moon's origin and evolution.
Project planners also wanted the mission to help to foster the country's knowledge, technology and talent pool for its future manned lunar missions and other deep-space expeditions.
The first man-made object from Earth to ever reach the moon was the Soviet spacecraft Luna 2. Instead of landing, it actually crashed into the moon in September 1959. The first soft-landing on our celestial neighbor was made by the Soviet Luna 9, in February 1966.
As the result of long-time persuasions by scientists, the Chinese government approved in January 2004 an overall plan for the country's lunar exploration program and officially opened the research and development work.
The first Chang'e probe was launched in October 2007. Since then, China has launched five lunar probes, including Chang'e 5, and one experimental spacecraft.
Before Chang'e 5, the Chang'e 4, which remains operational on the moon, was the most remarkable lunar mission by China as it is the first endeavor by any nation to conduct surface observation of the moon's far side, which never faces Earth, thereby accomplishing a goal sought by scientists for decades.
The design work on Chang'e 5 began in January 2011 and was concluded in December 2012, and then designers and engineers started building the probe's prototype. Construction for the Chang'e 5 began in December 2015 at the China Academy of Space Technology.
The mission was originally scheduled to be done by the end of 2017, but the plan had to be postponed due to technical problems on the Long March 5 rocket, which had a launch failure in July of that year.