China’s Chang’e-4 accomplishes mission goals

The photo of lunar lander Chang’e-4 taken by rover Yutu II on Friday. Photo: courtesy of China National Space Administration At 4:47 pm Friday, photos of two five-star red flags on China’s lunar lander and rover flashed on a screen at Beijing’s space flight and control center.

The images from the far side of the moon were eye-catching and inspiring as it marks a success for the country’s Chang’e-4 lunar probe mission and new accomplishment in man’s quest to know the earth’s satellite better.

China National Space Administration (CNSA) said on Friday that the lander Chang’e-4 and lunar rover Yutu II have taken photos of each other on the far side of the moon Friday afternoon and transmitted clear images to the ground, marking a complete success for the country’s lunar mission.

According to the CNSA, the transmission took place with the help of Queqiao relay satellite and marks the 5th winning streak in China’s lunar probe missions. The international payloads are also operating smoothly and probe data is being transmitted effectively.

Huang Jun, a professor at the School of Aeronautic Science and Engineering at Beihang University, told the Global Times that sending images from the other side of the moon is more difficult because transmitting signals is harder.

The photo of lunar rover Yutu II taken by lander Chang’e-4 on Friday. Photo: courtesy of China National Space Administration

Chang’e-4 probe made its first-ever soft landing on the far side of the moon on January 3. Over nine days, the probe has completed a series of procedures including establishing an independent data transmission link with Queqiao, starting the payload, detaching the rover from the lander, “noon nap” and waking up of the rover as well as taking photographs of each other. After this task, the mission will start scientific exploration and continue to study the lunar surface.

CNSA revealed that scientists have designed the route of the rover keeping in mind the surrounding terrain captured by a navigation camera and then used Queqiao to send out the photograph order. The panoramic camera of the rover clicked the lander, which took a picture of Yutu II with its topographic camera. Both images were processed on the earth.

Pei Zhaoyu, deputy director of the Lunar Exploration and Space Program Center of CNSA, explained to media that “shooting each other” refers to the lander and rover taking pictures of the side of the crafts with the national flag. “The lander’s side with the red flag faces the equator so the illumination is good. When the rover detached from the lander, it faced the South Pole so it needed to go around the lander to be able to have the flag in site. It needs to adjust its position and the angle of the panoramic camera to capture a clear image,” Pei said.

Huang said that controlling Chang’e-4 and Yutu II is required when they are taking photos and the control signal must be accurately transmitted from the ground to the far end of the moon via Queqiao.

Jiao Weixin, a space science professor at Peking University, told the Global Times that the rover’s camera is mainly used to observe the moon from a short distance and avoid obstacles. The ground staff sends instructions to move the rover to the site on which research needs to be conducted to collect data. “The main significance of shooting each other is to mark the occasion,” he said.

On December 15, 2013, rover Yutu and lander Chang’e-3 also photographed each other on the near side of the moon.

International cooperation

CNSA said that before the start of Chang’e-4 mission in December, the administration had “close communication” with US’ National Aeronautics and Space Administration (NASA) to discuss the use of its LRO satellite to observe the landing for scientific purposes.

The US said it would provide orbital data of the LRO to the Chinese team, while the Chinese side informed the US about the planned site and time of the lunar probe’s landing. Both sides expected cooperation to bear more scientific achievements.

Jiao told the Global Times that the US lunar exploration orbiter took photo of the landing of Chang’e-3, an unmanned lunar exploration probe. The picture shows our landing spot is very close to the meteor crater, “which means we used hover technology that successfully dodged the obstacle,” said Jiao.

The US will not seek cooperation with China unless the latter is strong, said experts, noting that the successful mission may lead to greater possibility of China-US cooperation.

“The US surpasses us in technology, but its lunar exploration task does not have a clear goal and faces controversy and pressure at home. On the contrary, China is steadily marching toward its goal,” said Jiao.

“Lunar exploration faces great technological and economic challenges, thus international cooperation is inevitable: after all, it’s not Cold War era anymore,” said Jiao.

“Science is borderless,” he

Posted in: AIR & SPACE
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