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  China's Chang'e 6 far side lunar sample mission

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Author Topic:   China's Chang'e 6 far side lunar sample mission
Robert Pearlman
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Posts: 52511
From: Houston, TX
Registered: Nov 1999

posted 05-03-2024 10:33 AM     Click Here to See the Profile for Robert Pearlman   Click Here to Email Robert Pearlman     Edit/Delete Message   Reply w/Quote
Xinhua state news agency release
China launches Chang'e-6 to retrieve samples from moon's far side

China on Friday (May 3) launched the Chang'e-6 spacecraft to collect and return samples from the moon's mysterious far side — the first endeavor of its kind in the history of human lunar exploration.

A Long March-5 rocket, carrying the Chang'e-6 spacecraft, blasted off from its launchpad at the Wenchang Space Launch Site on the coast of China's southern island province of Hainan at 5:27 p.m. Beijing Time (5:27 a.m. EDT or 0927 GMT).

Approximately 37 minutes after liftoff, the Chang'e-6 spacecraft separated from the rocket and entered its planned Earth-moon transfer orbit, which had a perigee altitude of 200 kilometers and an apogee altitude of about 380,000 kilometers, according to the China National Space Administration (CNSA).

The launch of the Chang'e-6 spacecraft was a complete success, the CNSA announced.

"Collecting and returning samples from the far side of the moon is an unprecedented feat. Now we know very little about the moon's far side. If the Chang'e-6 mission can achieve its goal, it will provide scientists with the first direct evidence to understand the environment and material composition of the far side of the moon, which is of great significance," said Wu Weiren, an academician of the Chinese Academy of Engineering and chief designer of China's lunar exploration program.

The Chang'e-6 spacecraft, like its predecessor Chang'e-5, comprises an orbiter, a lander, an ascender and a returner.

After it reaches the moon, it will make a soft landing on the far side. Within 48 hours after landing, a robotic arm will be extended to scoop rocks and soil from the lunar surface, and a drill will bore into the ground. Scientific detection work will be carried out simultaneously.

After the samples are sealed in a container, the ascender will take off from the moon and dock with the orbiter in lunar orbit. The returner will then carry the samples back to Earth, landing in north China's Inner Mongolia Autonomous Region. The entire flight is expected to last about 53 days, the CNSA said.

As the moon's revolution cycle is the same as its rotation cycle, the same side always faces Earth. The other face, most of which cannot be seen from Earth, is called the far side or "dark side" of the moon. This term doesn't refer to visible darkness, but rather the mystery shrouding the moon's largely unexplored terrain.

Remote-sensing images show the moon's two sides are very different. The near side is relatively flat, while the far side is thickly dotted with impact craters of different sizes and has much fewer lunar mares than the near side. Scientists infer that the lunar crust on the far side is much thicker than that on the near side. But why that is so remains a mystery.

An impact crater known as the Apollo basin, located within the South Pole-Aitken (SPA) Basin on the far side of the moon, has been chosen as the primary target landing and sampling site for the Chang'e-6 mission, according to Wang Qiong, deputy chief designer of the Chang'e-6 mission.

The colossal SPA Basin was formed by a celestial collision over 4 billion years ago and has a diameter of 2,500 kilometers, equivalent to the distance from Beijing to Hainan, and a depth of about 13 kilometers. It is the oldest and largest impact crater on the moon and in the solar system, and it may provide the earliest information about the moon, scientists say.

"First-hand, direct samples from the moon's far side are essential to giving us a deeper understanding of the characteristics and differences of the two sides of the moon, and to revealing the secrets of the moon," said Zeng Xingguo, a scientist at the National Astronomical Observatories of the Chinese Academy of Sciences.

"The whole mission is fraught with numerous challenges, with each step interconnected and nerve-wracking," Wang said.

In order to realize communication between Earth and the probe on the far side of the moon, China sent the Queqiao-2 relay satellite, whose name translates to "magpie bridge-2," into a highly elliptical lunar frozen orbit earlier this year.

Although the Chang'e-4 mission achieved the world's first soft landing on the far side of the moon in 2019, Chang'e-6 still faces significant risks as the rugged terrain of the moon's far side poses great challenges for its landing, space experts say.

The Chang'e-6 mission needs to see new technological breakthroughs in such areas as lunar retrograde orbit design and control, rapid intelligent sampling, and takeoff from the far side of the moon, Wang said.

"The amount of samples that Chang'e-6 can collect is uncertain and cannot be estimated accurately at present. Our goal is to collect 2 kilograms," said Deng Xiangjin, a space expert from the China Aerospace Science and Technology Corporation.

The Chang'e-6 mission is carrying four payloads developed through international cooperation. Scientific instruments from France, Italy and the European Space Agency/Sweden are aboard the Chang'e-6 lander, and a small satellite from Pakistan is aboard the orbiter.

Robert Pearlman
Editor

Posts: 52511
From: Houston, TX
Registered: Nov 1999

posted 05-08-2024 10:47 AM     Click Here to See the Profile for Robert Pearlman   Click Here to Email Robert Pearlman     Edit/Delete Message   Reply w/Quote
Xinhua state news agency release
Chang'e-6 enters lunar orbit after near-moon braking

China's Chang'e-6 lunar probe has successfully entered its circumlunar orbit, the China National Space Administration (CNSA) said on Wednesday (May 8).

At 10:12 a.m. Beijing Time (10:12 p.m. EDT on May 7 or 0212 GMT), Chang'e-6 successfully performed a near-moon braking procedure before entering the circumlunar orbit, according to the CNSA.

The near-moon braking procedure is a key orbital control for Chang'e-6 during its flight. The braking makes its relative speed lower than the lunar escape velocity, so that it can be captured by the moon's gravity and fly around the moon.

Supported by Queqiao-2 relay satellite, Chang'e-6 will later adjust the altitude and inclination of the orbit around the moon, and choose a proper time to carry out the separation of the orbiter-returner combination and the lander-ascender combination.

Then the lander-ascender combination will conduct a soft landing on the South Pole-Aitken Basin to carry out the sampling and return mission on the far side of the moon as planned.

Robert Pearlman
Editor

Posts: 52511
From: Houston, TX
Registered: Nov 1999

posted 06-01-2024 07:42 PM     Click Here to See the Profile for Robert Pearlman   Click Here to Email Robert Pearlman     Edit/Delete Message   Reply w/Quote
collectSPACE
China's Chang'e-6 lands on moon to bring back first far side samples

China has achieved its fourth robotic moon landing, advancing a mission to combine the feats of its two prior probes: touching down on the lunar far side and bringing samples back to Earth.

The China National Space Administration's (CNSA) Chang'e-6 spacecraft landed on target in the southern part of Apollo crater, located within the moon's South Pole-Aitken basin, on Saturday (June 1). The touchdown, at 6:23 p.m. EDT (2223 GMT or 6:23 a.m. Beijing time on June 2), came 24 days after the multi-module Chang'e-6 arrived in lunar orbit.

Robert Pearlman
Editor

Posts: 52511
From: Houston, TX
Registered: Nov 1999

posted 06-04-2024 04:24 AM     Click Here to See the Profile for Robert Pearlman   Click Here to Email Robert Pearlman     Edit/Delete Message   Reply w/Quote
China National Space Administration (CNSA) release
Chang'e 6 completes sampling, ascender takes off from the back of the moon and enters the planned lunar orbit

At 7:38 a.m. Beijing Time on June 4 [7:38 p.m. EDT or 2338 GMT on June 3], the Chang'e-6 ascender took off from the back of the moon with lunar samples. After the 3000N engine worked for about 6 minutes, it successfully sent the ascender into the predetermined lunar orbit.

Above: On June 3, 2024, the "mobile camera" [rover] carried by Chang'e-6 moved autonomously and successfully took and sent back a photo of the lander and ascender. (CNSA)

From June 2 to 3, Chang'e-6 successfully completed intelligent rapid sampling in the South Pole-Aitken Basin on the back of the moon, and packaged the precious lunar return samples in the storage device carried by the ascender in a predetermined form. During the sampling and packaging process, researchers simulated the geographical model of the sampling area and simulated sampling in the ground laboratory based on the probe data sent back by the Queqiao-2 relay satellite, providing important support for sampling decisions and operations in various links.

Intelligent sampling is one of the core key links of the Chang'e-6 mission. The probe withstood the high temperature test on the back of the moon, and collected lunar samples by drilling with drilling tools and surface sampling with a robotic arm, realizing multi-point and diversified automatic sampling.

Above: This image is a mosaic of color images taken by the panoramic camera of the lunar surface on the north side of the landing site before Chang'e 6 took samples. The top of the image is the Chaffee crater in the north of the landing site, and the bottom of the image is the landing leg and the lunar soil that was squeezed and bulged during the landing. (CNSA)

The Chang'e-6 lander was equipped with a variety of payloads, including a landing camera, a panoramic camera, a lunar soil structure detector, and a lunar mineral spectrometer, which were powered on normally and carried out scientific exploration as planned, playing an important role in scientific exploration tasks such as the detection and research of lunar surface morphology and mineral composition, and the detection of lunar shallow structure. Before the probe drilled and sampled, the lunar soil structure detector analyzed and judged the underground lunar soil structure in the sampling area, providing data reference for sampling.

The international payloads carried by the Chang'e-6 lander, such as the European Space Agency's lunar surface negative ion analyzer and the French lunar radon gas detector, worked normally and carried out corresponding scientific exploration tasks. Among them, the French lunar radon gas detector was powered on during the Earth-Moon transfer, the lunar orbit phase, and the lunar surface working section; the European Space Agency's lunar surface negative ion analyzer was powered on during the lunar surface working section. The Italian laser corner reflector installed on the top of the lander became a position control point that can be used for distance measurement on the back of the moon.

After the surface sampling was completed, the five-star red flag carried by the Chang'e-6 lander was successfully unfolded on the back of the moon. This is the first time that China has independently and dynamically displayed its national flag on the back of the moon. The national flag is made of new composite materials and special technology. Due to the different landing location on the moon, the Chang'e-6 national flag display system has been adaptively improved on the basis of the Chang'e-5 mission.

Compared with the ground takeoff, the Chang'e-6 ascender does not have a fixed launch tower system, but uses the lander as a "temporary tower." Compared with the Chang'e-5 lunar surface takeoff, Chang'e-6 took off from the back of the moon and could not get direct ground measurement and control support. Instead, it needed to achieve autonomous positioning and attitude determination with the help of the Queqiao-2 relay satellite and the special sensors it carried, which made the project implementation more difficult. After the Chang'e-6 ascender ignited and took off, it went through three stages of vertical ascent, attitude adjustment and orbital injection, and successfully entered the scheduled circumlunar flight orbit.

Subsequently, the ascender will rendezvous and dock with the orbiter and returner combination waiting in the circumlunar orbit, and transfer the lunar samples to the returner; the orbiter and returner combination will fly around the moon, waiting for the right time to return for the lunar-to-earth transfer, and the returner will re-enter the atmosphere with the lunar samples near the earth, and is scheduled to land at the Siziwang Banner landing site in Inner Mongolia.

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