China’s Chang’e 5 enters crucial 48 hours of its mission after moon landing

04-Dec-2020 Intellasia | South China Morning Post | 6:02 AM Print This Post

Space exploration is full of drama. On Tuesday, the very day that China’s Chang’e 5 spacecraft landed on the moon and started gathering the first lunar rock samples in over 40 years, the giant radio dish collapsed at the Arecibo Observatory, a legendary icon of American ambitions to conquer deep space.

“Congratulations to the China National Space Administration,” the European Space Agency (ESA) tweeted. The ESA also retweeted the news about Arecibo, the radio telescope in Puerto Rico that the United States last month decided to withdraw from service after more than half a century of operation.

Those sentiments were echoed in space research communities across the globe. To some, the two events felt symbolic.

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A technically challenging landing by Chang’e followed persistent and increasing funding of space programmes by the Chinese government, while Arecibo has struggled for years and had its budget cut in Washington.

“We must be clear that China is still behind the US in many areas [including space],” Professor Wu Xuebing, director of the department of astronomy at Peking University, said. “But we hope to catch up one day.”

Chang’e 5 initiated a brake sequence more than a week after its launch from the Wenchang space centre in the southern island province of Hainan. Within about 15 minutes, the spacecraft slowed from 6,120km/h (3,803mph) to almost zero in a strictly planned descent.

It was a challenging job that required powerful rocket engines with extremely precise control. A year ago, India’s lunar craft Vikram applied the brake a little too hard and crashed.

China has landed two rovers on the moon before, but this mission had an additional challenge. Chang’e 5 is the tallest Chinese spacecraft on the moon, so it is easier to flip if it lands on an uneven surface.

The ground control could only sit and watch the last stage of landing, because of a radio communication delay, while the spacecraft made critical decisions such as avoiding slopes and rocks by itself using various sensors and artificial intelligence technology.

Chinese scientists hope to retrieve some samples that are different from those brought back by past American and former Soviet missions.

Chang’e 5 landed near Mons Rumker, a volcano believed to be still active. The rocks and dust there could therefore be the most recent on the moon. The area is also rich in radioactive elements such as uranium, and only samples can help to explain their mysterious presence.

Time will be tight. The spacecraft had only a solar battery, so it must complete all of its tasks within 48 hours before a long, cold night falls.

A robotic arm will gather some rocks and dust from the surface while a two-metre drill retrieves samples from underground. The samples will be packed into a canister and depart with an ascent spacecraft.

It was a high-risk mission for China because many new technologies were used for the first time, Luan Enjie, a chief designer of previous lunar missions, said.

For instance, the drill samples need to be loaded into the canister and sealed perfectly, otherwise they risk being contaminated by the Earth environment. And the re-entry capsule will arrive at a speed so high that it would burn if it were to directly plunge into the atmosphere.

“So we will let it bounce like a skipping stone before coming down,” Luan told state broadcaster China Central Television on Wednesday.

The plan is for some seeds of crops and plants to return with the lunar rock samples, a space scientist involved in the mission told the South China Morning Post.

They hope to analyse the contents of these samples to see whether they would support growing food. The scientist involved did not rule out the possibility of using some of the dust collected to cultivate the seeds. “It is definitely a good idea,” he said. Wu said he regretted that the Arecibo collapse coincided with the Chang’e landing. The facility had formerly been the world’s largest single-dish telescope for decades. It even sent a radio message to a possible intelligent alien civilisation in star cluster M13 in 1974.

Chinese scientists have used a lot of data collected at the Arecibo in their research, according to Wu.

But the facility in Puerto Rico was getting old. Its distant location outside the US mainland increased the costs of upgrades and maintenance.

It was damaged by several tropical storms and earthquakes, the latest occurring in January, before vital cables broke in August and last month. But debate within the US research community over whether it should be abandoned had begun much earlier.

The completion of the Fast (five-hundred-metre aperture spherical telescope) facility in southwest China was also likely to have diminished Arecibo’s remaining usefulness to the US government, according to several astronomers.

Located in Pingtan, Guizhou province, Fast is more than 60 per cent larger than Arecibo in diameter and, with newer designs, technology and materials, outperformed it by all measures when it was completed in 2016.

But the astronomers said the design of Fast had applied lessons learned from Arecibo, and only Arecibo could verify some of Fast’s important findings.

“They were like a couple. When one is gone, the other will be lonely,” one astronomer based in Beijing said.

Competition in space between China and the US is expected to intensify. China will soon start building a full-scale space station, land its first rover on Mars and invite other countries to jointly construct a robotic base on the moon.

The US aims to launch the giant James Webber space telescope, test a new heavy rocket and send a female astronaut to the moon by 2024 if the incoming administration of president-elect Joe Biden sticks to the existing plans.

“It is difficult to say who will win in the end,” Wu said. “But if China and the US can join hands, it will be a win for the human race.”

https://sg.news.yahoo.com/china-chang-e-5-enters-121741108.html

 

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