Chang'e-5 probe unfolds Chinese national flag, takes off from moon with lunar surface samples
By Deng Xiaoci and Fan Anqi Source: Global Times Published: 2020/12/3 23:31:40
The Chinese national flag shines an even brighter red from moon, and from now on it will be a grand reminder for stargazers from all over the world of the excitement and inspiration we felt from Apollo missions more than half a century ago.
Having packed samples of soil and rocks from the Earth's only natural satellite within 19 hours after its smooth soft landing, the ascender of the Chinese spacecraft using the lander as a launch pad, took off from the moon surface, according to the China National Space Administration Thursday evening.
The Chinese space agency said in a statement the CNSA sent to the Global Times on Thursday evening, the Chang'e-5 ascender has successfully taken off from the lunar surface with soil and rock samples, and sent to the lunar orbiter some 15 kilometers away with the 3,000-newton thrust engine.
Right before the lift-off of Chang'e-5's ascender from lunar surface, the lander vehicle of the Chinese spacecraft unfolded the five-star red national flag, a genuine one made from fabrics, marking a first in the country's aerospace history.
The probe's successful launch from the lunar surface, as some observers believe, marks the completion of probably the most challenging step in the mission.
"This is the first attempt in China's aerospace history to lift off from a celestial body other than Earth," chief editor of Aerospace Knowledge magazine Wang Ya'nan said. "The launch is a major test, in that the vehicle had to rely entirely on automatic maneuvers without any ground command."
Wang explained to the Global Times that the launch from the moon could not afford any time delay. "If the probe receives a command from the Earth to help it control the separation, altitude and speed, there will be at least one second delay, which will put the process in great danger."
Another factor that posed a challenge to the lunar takeoff is that the lander-ascender combination might sit on a slope, which would bring uncertainty to the probe's altitude and position. It means that the probe must ensure its own altitude is precise enough to enter the designated orbit through automatic decision-making, according to a statement sent to the Global Times from the China Aerospace Science and Technology Corporation (CASC.)
Chinese researchers have conducted numerous ground simulations to verify the takeoff, but the particularities of the lunar environment have made the verifications difficult, the CASC said.
The rendezvous and docking, if successful, could be of great value to other deep-space or even manned missions in the future, the significance of which would be no less than the Apollo mission, once the name card of human lunar exploration activities during the Cold War, Chinese analysts said.
"It will be a milestone for China's aerospace development," Song Zhongping, an aerospace expert and TV commentator, said, calling it "a foresighted practice that lays a technological foundation for future deep-space explorations."
It will also verify the viability of manned lunar landing missions, and even the construction of a lunar research base, or Mars missions, he told the Global Times.
Lunar surface substances the lander vehicle collected by scooping and drilling the landing area in around 19 hours, have been sealed and packed in a vacuum container on board the ascender, CNSA said earlier on Thursday.
Payloads on board the Chang'e-5 lander vehicle, including its lunar soil composition analytical instrument, are working normally, carrying out planned scientific tasks and providing information support for sampling.
After taking off from the lunar surface, the ascender will rendezvous and dock with an orbital module which is flying and waiting in orbit at an average altitude of 200 kilometers above the moon. The re-entry capsule will then carry the lunar sample and bring them to a designated site in North China's Inner Mongolia Autonomous Region by mid-December.
Flag mission accomplished
More stylish than previous Chang'e landing missions, the lander of Chang'e-5 displayed the five-star red national flag, made of genuine fabric, on the moon.
The Chinese national flag made its moon debut in December 2013 during the country's first lunar landing mission of Chang'e-3, and it was recorded in pictures from the spacecraft's lander and its rover Yutu-1 took for each other.
Chang'e-4 lander and rover Yutu-2 brought China's national flag to the dark side of the moon, as the Chinese spacecraft made a historic landing in the unvisited region in January 2019.
The flags that Chang'e-3 and -4 carried were in the form of the craft's coatings, rather than an actual flag. Chinese space technological development has allowed it to take a step forward in the Chang'e-5 mission, the third consecutive safe soft landing on the moon in seven years.
The Chang'e-5 flag presentation system was developed by China Space Sanjiang Group under the State-owned China Aerospace Science and Industry Corporation, better known as the CASIC.
To ensure a complete and smooth unfolding of the flag, the system adopted a secondary rod-type structure, which is applied in solar panel extending for satellites and other types of spacecraft, CASIC developers told the Global Times on Thursday.
The system weight has been controlled at around one kilogram, and all connecting parts of the system have been given special protection, such as coldness-resistance measures, to help overcome unfavorable lunar surface conditions, including a drastic temperature difference on the moon ranging from 150 C to minus 150 C, Li Yunfeng, the project leader, said in a statement the CASIC company sent to the Global Times.
"An ordinary national flag on Earth would not survive the severe lunar environment," so the research team also spent more than a year selecting the proper materials to make sure the eventual flag would be strong enough, survive under extreme coldness and heat and capable of showing the fine colors of the national flag and remain so forever, said Cheng Chang, another leading member of the developer team.
The national flag, 2,000 millimeters wide and 900 millimeter tall, represents cutting-edge technology, they said.
How to preserve its original color and shape are the two most crucial questions in designing a national flag that must survive more than 380,000 kilometers away from Earth, under extreme temperatures and radiation during its journey, Wang Ya'nan told the Global Times.
To get a sense of how difficult the task it is, five of the six flags (except for the one Apollo 11 placed on the moon) brought to the moon in the late 1960s and early 1970s during six US crewed moon landings, have been bleached white due to decades-long solar radiation, although they are reportedly still standing and casting shadows.
Many reports say the Apollo 11 flag was blown over by the exhaust from the ascent engine during lift-off.
The Soviet Union was the first country to imprint its national symbol on the moon, with a football-sized metal ball, carved with its national flag, full of explosives, smashing to the lunar ground in the Luna 2 mission in 1959.
Compared to such a method, China has a more advanced approach, which also greatly increased the complexity of the design, Wang noted.
The Chinese flag that Chang'e-5 displayed officially became the first and only fabric national flag that has ever been placed on the moon in the 21st century, which reminds many of the classic footage of an American national flag planted by Neil Armstrong in the Apollo 11 lunar mission more than five decades ago, observers said.
And they hailed that as the fresh and new icon of human's lunar exploration, the Chinese national flag would inspire today's mankind, just as Apollo 11 did, encourage and celebrate generations to make an endeavor to space.
Displaying a national flag on a celestial body represents the comprehensive strength and technological advancement of the country, Song noted.
"Yesterday's memory is still fresh and clear, when the US astronauts stepped outside their cabins and planted the first flag in human history, an American national flag, on the moon in 1969," Song Zhongping recalled. "But China is about to showcase our own national flag as well, which I believe is a recognition of the achievements and breakthroughs that we have made, which will be the most valuable thing."
Some readers have left comments under images and video of the Chang'e-5 landing published on the Global Times twitter account in recent days, saying they would not be convinced and acknowledge China's achievements until the lander takes an actual photo of the American flag planted by the previous Apollo mission.
"Is it an original video, or a TikTok post taken in the Gobi desert," one Twitter user wrote. "Where is the lunar dust while landing," another asked.
The landing was closely followed by space agencies from all over the world, and the European Space Agency, Russia's Roscosmos and NASA scientists have extended their congratulations.
Pang Zhihao, a senior space expert based in Beijing, said "the lander vehicle of Chang'e-5 was designed to turn off its engine about two meters above the surface to deliberately avoid blowing dirt."
And for the sake of innovation, the lander touched down on an unvisited region, which explains why there were no US craft nearby, Pang said.
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