Lunar Probe
China’s Unmanned Spacecraft Returns to Earth
After successfully landing on moon and collecting samples from the lunar surface, China’s unmanned spacecraft, Chang’e 5 landed back on Earth on December 17, 2020. The China National Space Administration (CNSA) said in a statement that Chang’e 5’s re-entry capsule touched down on its landing site in Inner Mongolia autonomous region. The recovery team is making initial processing of the capsule and will then use a plane to transport it to Beijing where it will be opened for technicians to remove the container holding lunar samples.
The successful landing marked the completion of the 23-day expedition of Chang’e 5, 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. The entire unmanned mission, has returned with over 4 pounds of rock and soil sample from the surface of the moon.
As next steps, 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, CNSA noted. It also informed that a certain proportion of the samples will also be on public display to enhance science awareness among the public, especially young generations.
The space administration had earlier informed that the rocks and dust from the moon have been delivered from Chang’e 5’s ascender to their final host - the probe’s re-entry capsule, which will bring them to Earth. Chang’e 5, China’s largest and most sophisticated lunar probe had four main components - an orbiter, lander, ascender and re-entry capsule. The spacecraft was launched on November 24, 2020 by a Long March 5 heavy-lift carrier rocket, the biggest and mightiest launch vehicle in China, at the Wenchang Space Launch Center in Hainan province, setting out on China’s most challenging lunar adventure and the world’s first mission since 1976 to bring lunar samples to Earth.
The rocket was tasked with placing the 8.2-metric tonne Chang’e 5 in an Earthmoon transfer trajectory. As the landing procedures began, the lander-ascender combination of the 8.2-metric tonne Chang’e 5 started its 7,500-newton-thrust engine to reduce its flying speed and began to descend toward the moon from about 15 kilometers above the lunar surface. When the lander-ascender reached an altitude of 2.5 km, it conducted a rapid positional adjustment and continued approaching the lunar surface. The lander-ascender suspended its descent when it was about 100 meters from the moon and hovered for a short time to carry out accurate detection of obstacles before continuing to descend at a slower, steady speed. 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. Shortly after the landing, it began to use a drill to obtain samples from 2 meters beneath the lunar surface,” CNSA noted. 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 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, the space administration highlighted.
The landing combination made an engineassisted touchdown on the moon and later conducted assignments as using a cutting-edge drill to obtain underground rocks from 2 meters beneath the surface and a mechanical arm to gather surface dirt. The 400-kilogram ascender docked with the 2.3-metric ton orbiter re-entry capsule combination transferred a sealed container holding 2 kilograms of lunar samples into the capsule. The operation was the first automated rendezvous and docking of any spacecraft in lunar orbit. The last time two components of a spacecraft docked with each other in lunar orbit was in December 1972 during the final Apollo mission, and that was monitored and controlled by astronauts, CNSA pointed out. One of the most crucial devices during the highly sophisticated docking maneuver was a microwave radar, which is mounted on the orbiter that worked with its transponder on the ascender to measure the rapidly changing distance and provided communication between the two traveling vehicles to allow them to adjust their position during the docking. Several hours after the docking, the ascender departed from the orbiter re-entry capsule combination and the combination continued orbiting the moon before its journey back to Earth, the space administration said in a statement.
After the two-day surface operations were done, the ascender’s rocket elevated it to lunar orbit to rendezvous and dock with the re-entry module. After the underground operation, the recovering of surface dirt, and completion of all collection and packing processes, samples were packed into a vacuum container inside the ascender. Chang’e 5 was supposed to work for about two days in a region to the north of Mons Ruemker, a mountain overlooking a vast lunar mare called Oceanus Procellarum, or the Ocean of Storms, on the western edge of the moon’s near side. The area is said to have never been visited before Chang’e 5 mission.
The ascender activated an engine to lift itself into an elliptical lunar orbit to prepare for docking with the re-entry capsule, marking the first time a Chinese spacecraft has blasted off from an extraterrestrial bod, stated CNSA. Upon arrival in Earth’s orbit, the pair separated in due course, and the re-entry capsule conducted a series of complicated maneuvers to return to a preset landing site in North China’s Inner Mongolia autonomous region.
A total of about 382 kilograms of lunar rocks and dust were recovered by the US Apollo mission astronauts and the Soviet Luna robotic landers from 1969 to 1976. Back on the lunar surface, the lander will continue using its three scientific payloads to carry out survey and measurement -- the panoramic camera is tasked with mapping the topography of the landing site; the infrared spectrometer will determine the physical composition of stones and dirt around the landing site; and the soil measurement instrument will detect and analyse the subsurface structure of the drilling point. The orbiterreentry capsule is in lunar orbit at an average altitude of about 200 km above the moon, according to the space administration.
In a published statement, the space administration stated that the Chang’e 5 mission is intended to fulfill several objectives. “In terms of space engineering, it will demonstrate and verify technical plans and apparatus for autonomous lunar sampling and packing, and moon-based launching, as well as lunar orbital docking. In the scientific field, it will investigate the landing site’s geological and topographic features, and enable scientists to analyse the lunar samples’ structure and physical traits so they can deepen their research into the moon’s origin and evolution.” CNSA further added that the mission will also help to foster the country’s knowledge, technology and talent pool for its future manned missions to the moon and other deep-space expeditions. Pei Zhaoyu, spokesman for the Chang’e 5 mission, said if the mission becomes successful, it will be a milestone in the nation’s lunar exploration endeavor and will show the world China’s scientific, technological and engineering capabilities. Furthermore, Chang’e 5 will strengthen the nation’s status and influence in the international space community, pave the way for the country’s future lunar expeditions and boost its space science, and will offer more opportunities to lunar researchers around the world, he said. Scientists around the world are welcome to participate in the research related to the lunar samples brought back by the mission. This would not only be a significant moment in the space exploration of China but also the world.