In a glorious conclusion to its journey to the moon, the return capsule of China’s Chang’e-5 probe touched down on Earth at 1:59 am on December 17. It carried the country’s first samples collected from the moon; the world’s first lunar samples since 1976.

An illustration shows the orbital transfer injection by Chang’e-5’s orbiter-reentry capsule combination. [IMAGE: CNSA]

China’s most sophisticated and challenging space adventure – the Chang’e-5 robotic lunar mission – ended successfully early on the morning of December 17, when its payload of rocks and dust from the moon landed on the grasslands of northern China.

The China National Space Administration (CNSA) said in a statement that Chang’e-5’s reentry capsule touched down at its preset landing site in Siziwang Banner of the Inner Mongolia Autonomous Region at 1:59 am.

The recovery team will make an initial assessment of the capsule and then use a plane to transport it to Beijing where it will be opened by technicians. These technicians will then remove the container holding the lunar samples, the administration said.

The reentry and landing started around 1:00 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 1:33 am at the second cosmic velocity, or 11.2 kilometers per second, and soon bounced off the atmosphere to further slow down its ultrafast speed that could have caused damage to the vehicle. Later, the craft reentered the atmosphere at the 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 landed smoothly on the snow-covered grasslands. Recovery personnel sent from the Jiuquan Satellite Launch Center soon arrived at 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, and also made China the third country to achieve this feat after the United States and the former Soviet Union.

Recovery personnel work at the landing site of the return capsule of the Chang’e-5 probe in Siziwang Banner, North China’s Inner Mongolia Autonomous Region, on December 17, 2020. [IMAGE: CHINA DAILY]

Chang’e-5, China’s largest and most advanced lunar probe, consisted of four main components — an orbiter, a lander, an ascender and a reentry capsule. The spacecraft was launched by a Long March-5 heavy-lift carrier rocket early on November 24 at the Wenchang Space Launch Center in South China’s Hainan Province, kick-starting China’s most difficult space project ever and the world’s first lunar sample-return mission since 1976.

Recovery personnel work at the landing site of the return capsule of the Chang’e-5 probe in Siziwang Banner, North China’s Inner Mongolia Autonomous Region, on December 17, 2020. [IMAGE: CHINA DAILY]

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 November 30.

Late on December 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 the Chang’e-5 mission.

Shortly after landing, the combination began to fulfill its major tasks. It used a drill to obtain 500 grams of underground samples and then employed a mechanical arm to scoop up 1.5 kg of surface dust. Samples were packed into a vacuum container inside the ascender.

Staff workers hoist the return capsule onto a vehicle in Siziwang Banner, North China’s Inner Mongolia Autonomous Region, on December 17, 2020. [IMAGE: CHINA DAILY]

The lander also unfurled the first free-standing Chinese national flag on the moon.

The ascender activated an engine late on December 3 to lift itself into an elliptical lunar orbit in preparation 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 December 6 and transferred the lunar samples into the reentry capsule. The ascender separated from the combination later that day and was sent back to the moon on December 8.

The return capsule of the Chang’e-5 probe lands in Siziwang banner, North China’s Inner Mongolia autonomous region, on December 17, 2020. [IMAGE: CHINA DAILY]

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 December 13 and began to fly back towards Earth.

According to the space administration, the Chang’e-5 mission was designated to fulfill several objectives. In terms of space engineering, it needed to demonstrate and verify technical plans and apparatus for autonomous lunar sampling and packing, moon-based launching, and lunar orbital docking. In a scientific context, it was tasked with investigating the landing site’s geological and topographic features, and enabling scientists to analyze the lunar samples’ structure and physical traits so they can deepen their research into the 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 extended lobbying by scientists, in January 2004 the Chinese government approved 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.

The vessel containing lunar rocks and soil is handed over to the National Astronomical Observatories in Beijing on December 19. [IMAGE: CHINA DAILY]

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 observations on 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 on 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.

Source: China Daily