China launches Wentian space station module with giant rocket


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Another large Chinese rocket was launched into space on Sunday at 2:22 pm Beijing time, and again no one knows where or when it will fall.

This will be a repeat of two earlier launches of the same Long March 5B rocket, which is one of the largest in use today. For about a week after launch, space debris watchers from around the world will watch the 10-story, 23-ton rocket booster as wisps of air friction slowly drag it down.

The likelihood of it hitting anyone on Earth is slim, but significantly higher than what many space experts consider acceptable.

The powerful rocket was designed specifically to launch parts of China’s Tiangong space station. The latest mission raised Wentian, a laboratory module that will expand the station’s research and development capabilities. It will also add three more places for astronauts to sleep and another airlock for spacewalks.

The completion and operation of the space station are described in state media as important to China’s national prestige. But the country has suffered some damage to its reputation during previous rocket flights.

After the first launch of a Long March 5B in 2020, the booster re-entered West Africa, with debris causing damage but no villages in the Ivory Coast.

The booster from the second launch in 2021 crashed harmlessly in the Indian Ocean near the Maldives. However, Bill Nelson, NASA Administrator, issued a statement criticizing the Chinese. “It is clear that China is not meeting responsible standards for its space debris,” he said.

China dismissed these criticisms with great fanfare. Hua Chunying, a senior Foreign Ministry official, accused the United States of “hype”.

“In the past few days, the US and several other countries have been promoting the landing of Chinese missile debris,” Ms. Hua said. “To date, there have been no reports of damage from landing debris. I have seen reports that since the launch of the first artificial satellite more than 60 years ago, there has not been a single incident where debris has hit someone. American experts estimate the chances of this being less than one in a billion.”

China’s space agencies did not respond to a request for an interview about the upcoming launch.

Space has enormous prestige for the Chinese government, which sees every major launch as an increase in its space power, said Namrata Goswani, author of Fight for the Sky: Great Power Competition for Control of Space Resources.

According to Dr. Goswani, China has surpassed Russia in the sophistication of its space program. “China is ahead of the Russian space program in terms of its lunar and Martian programs, as well as its military space organization,” she said.

On a sunny and warm morning, crowds of Chinese space enthusiasts scattered along the beach near the rocket launch site on Hainan Island in the south of the country. Others crowded the rooftops of the hotels along the beach.

Zhang Jingyi, 26, set up her camera on the roof of a hotel along with about 30 other people on Sunday morning.

According to her, this was her 19th “missile chase” trip. She booked a hotel room four months ago.

“There are more people there than ever,” she said.

Ms. Zhang gave the rocket a nickname fans use: “Fat Five.” “When it is launched, there will be a small earthquake,” she said.

China has landed a rover on the far side of the moon, collected lunar material and brought it back to Earth for scientific research, and landed and operated a rover on Mars. The United States is the only country to have accomplished this latest feat.

“China hasn’t done or done anything that the US hasn’t already done in space,” said Joan Johnson-Freese, a US Naval War College professor and former chair of national security. “But it’s reaching technical parity, which is very worrying for the US.”

She likened the Chinese space program to a tortoise compared to an American hare, “although the tortoise has sped up considerably in recent years.”

As of April this year, China has completed a total of six space station construction missions. Three crews of astronauts lived on board the station, including a trio that will receive the Wentian module this week.

Approximately 15 minutes after launch, the launch vehicle successfully placed the Wentian spacecraft on its intended orbital trajectory. It should rendezvous with the Tianhe space station module about 13 hours after launch. The Chinese space agency has given no indication that it has made any changes to the launch vehicle.

“It will be the same story,” said Jonathan McDowell, an astrophysicist at the Center for Astrophysics in Cambridge, Massachusetts, who tracks the appearance and disappearance of objects in space. “Perhaps the rocket designers could have made some minor changes to the rocket that would have allowed them to then deorbit the stage. But I don’t expect it.”

If the design of the rocket has not changed, no engines will control its descent, and the booster engines cannot be restarted. The last shower of debris, with several tons of metal expected to survive all the way to the surface, could occur anywhere along the path of the launch vehicle, which travels north to 41.5 degrees north latitude and south to 41.5 degrees north. degrees south latitude.

This means that there will be no danger to Chicago or Rome, which are slightly north of the orbital trajectories, but Los Angeles, New York, Cairo and Sydney, Australia are among the cities that the booster will fly over.

The science of predicting where a tumbling rocket stage will land is complex. Earth’s atmosphere inflates and deflates depending on how much the sun shines on a given day, and this phenomenon speeds up or slows down the rate of fall. If the calculation was wrong by half an hour, the falling debris had already traveled a third of the way around the Earth.

By design, the center stage of the Long March 5B launch vehicle will push the Wentian module, which is more than 50 feet long, into full orbit. This means that the booster will also reach orbit.

This is different from most rockets, whose lower stages typically return to Earth immediately after launch. The upper stages that reach orbit typically restart the engine after releasing the payload, guiding them towards atmospheric re-entry over an unoccupied area, such as the middle of the ocean.

Malfunctions sometimes cause unintended, uncontrolled re-entries, such as the second stage of a SpaceX rocket that crashed over Washington State in 2021. But the Falcon 9 stage was smaller, about four tons, and less likely to cause damage or injury.

The US and NASA have not always been as careful as they are now when re-entrying large objects into the atmosphere.

Skylab, America’s first space station, crashed to Earth in 1979, with large debris falling into Western Australia. (NASA has never paid a $400 fine for trash.)

NASA also did not plan to scrap its Upper Atmosphere Research Satellite, or UARS, after the completion of that mission in 2005. Six years later, as a dead satellite the size of a city bus was heading towards the out-of-control entrance, NASA calculated that there was a 1 in 3,200 chance that someone could be injured. It ended up crashing into the Pacific Ocean.

Typically, 20 to 40 percent of rockets or satellites survive re-entry, said Ted Mühlhaupt, a debris expert with Aerospace Corporation, a nonprofit heavily funded by the federal government that does research and analysis.

This suggests that a 10,000 to 20,000 pound Long March 5B booster could hit the Earth’s surface.

Mühlhaupt said the United States and some other countries avoid uncontrolled re-entry of space debris if the chances of someone on earth being injured are higher than 1 in 10,000.

To date, not a single case is known when someone was injured by the fall of man-made space debris.

“That number of 1 in 10,000 is somewhat arbitrary,” Mr. Mühlhaupt said. “It’s been widely accepted, and recently there’s been concern that when a lot of objects come back into the system, they stack up to the point where someone might get hurt.”

If the risk is higher, “it’s pretty common practice to dump them in the ocean,” said Marlon Sorge, executive director of the Aerospace Corporation’s Center for Orbital and Re-entry Debris Research. So you know you won’t hit anyone.

Mr Mühlhaupt said that without details of the design of the Chinese missile, it is impossible to calculate a risk assessment. But “I’m very confident it’s above the threshold” of a 1 in 10,000 risk, he added. “Far above the threshold.”

The Long March 5B launch vehicle is about three times as massive as UARS. Approximately, it can be assumed that this is three times the risk of 1 in 3200 that NASA estimated for UARS, and possibly higher.

“In a way, that’s three UARS,” said Dr. McDowell. According to him, the likelihood that this launch vehicle could injure someone “could be as high as one case in several hundred.”

During a pre-launch broadcast on CGTN, Chinese state media Xu Yansong, a former Chinese National Space Administration official, referred to the 2020 Ivory Coast incident. Since then, he says, “we have improved our technology.” shoot down a rocket stage in a deserted area, but he didn’t give any specifics.

The same series of events may soon play out again.

In October, China will launch a second Mengtian laboratory module into orbit to complete the assembly of Tiangong. It will also fly on another Long March 5B rocket.

Li Yu contributed to the study.

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