Another large Chinese rocket was launched into space on Sunday at 2:22 pm Beijing time, and once again, no one knows where and when it will land.
It will be a re-launch of two earlier missiles from the same missile, the Long March 5B, one of the largest currently in use. For about a week after launch, the world’s space debris watchers will track the 10-story, 23-ton rocket as filaments of atmospheric friction slowly pull it down.
The chance of hitting anyone on Earth is low but much higher than what many space experts consider acceptable.
The powerful rocket is specifically designed to launch parts from the Chinese space station Tiangong. The final mission lifted the Wentian, a laboratory unit that will expand the station’s scientific research capabilities. It will also add three additional sleeping areas for astronauts and another air lock for them to conduct spacewalks.
The completion and operation of the space station has been described in state media as important to China’s national standing. But the country did some reputational damage during the missile’s previous flights.
After the first Long March 5B launch in 2020, the booster re-entered over West Africa, with debris causing damage but no casualties in villages in the Ivory Coast nation.
Booster from the second launch, in 2021, Harmlessly scattered in the Indian Ocean near the Maldives. However, Bill Nelson, Administrator of NASA, issued a statement criticizing the Chinese. “It is clear that China is failing to meet responsible standards regarding space debris,” he said.
China rejected this criticism with great fanfare. Senior Foreign Ministry spokeswoman Hua Chunying accused the United States of “hype”.
“The United States and a few other countries have accelerated the landing of Chinese missile debris over the past few days,” Ms. Hua said. “So far, no damage from landing debris has been reported. I have seen reports that since the launch of the first man-made satellite more than 60 years ago, there has not been a single incident where a piece of debris hit a person. American experts estimate the chances of That’s less than one in a billion.”
Chinese space agencies did not respond to a request for an interview about the upcoming launch.
Space is of enormous prestige for the Chinese government, which sees every major launch adding to its space power buildup, said Namrata Goswani, author of “Scramble for Heaven: A Superpower Competition for Control of Outer Space Resources.”
Dr. Goswani said that China has overtaken Russia in the development of its space program. “China is ahead of the Russian space program in terms of its lunar and Mars programs, as well as the organization of military space,” she said.
On a warm, sunny morning, crowds of Chinese space fans swarmed across the beach near the rocket launch area on Hainan Island in the south of the country. Others crowded the rooftops of hotels along the beachfront.
Zhang Jingyi, 26, put her camera on the roof of a hotel with about 30 others on Sunday morning.
She said it was her 19th flight to “chasing missiles.” I booked her hotel four months ago.
“There are more people than ever,” she said.
Seconds before the rocket took off, “everyone started to count down. Then the crowd exploded in cheers and exclamations,” she said in a later interview.
China landed a rover on the far side of the moon, collected lunar materials and brought them back to Earth for scientific study, and landed a rover on Mars. The United States is the only other country to achieve this latest feat.
“China has not and has not done anything that the United States has not already done in space,” said Joan Johnson-Freese, a professor at the U.S. Naval War College and former chief of the Department of National Security Affairs. “But it is reaching technical parity, which is a major concern for the United States.”
She likened the Chinese space program to a tortoise compared to the American hare, “although the tortoise has accelerated significantly in recent years.”
As of April, China has completed a total of Six missions to build the space station. Three crews of astronauts lived aboard the station, including the trio that will receive the Wentian unit this week.
About 15 minutes after launch, the rocket’s booster successfully placed the Wentian spacecraft on its intended orbital path. It is scheduled to rendezvous with the Tianhe space station module about 13 hours after liftoff. The Chinese space agency has not given any indication that it has made any changes to the booster.
“It’s going to be the same story,” said Jonathan McDowell, an astrophysicist at the Center for Astrophysics in Cambridge, Massachusetts. Tracks the comings and goings of things in space. “It is possible that the missile designers made some subtle changes to the missile that would then allow them to disengage the platform by thrust. But I don’t expect that.”
If the rocket design does not change, no thrusters will guide its landing, and the booster engines cannot be restarted. The last rain of debris, with a few tons of metal expected to remain all the way to the surface, could occur anywhere along the path of the booster, which travels north as far as 41.5 degrees north latitude and up to 41.5 degrees south latitude.
This means there will be no danger to either Chicago or Rome, both of which are located slightly north of the orbits, but Los Angeles, New York, Cairo and Sydney, Australia, are among the cities over which the craft will travel.
The science of predicting where a rocket’s fall stage will fall is tricky. The Earth’s atmosphere bulges and contracts depending on how bright the sun is on a given day, and this phenomenon speeds up or slows down the rate of fall. If the calculation was stopped by half an hour, the falling debris would have traveled a third of the distance around the world.
By design, the Long March 5B central booster stage will propel the Wentian module, which is more than 50 feet long, into orbit. This means that the booster will also reach orbit.
This differs from most rockets, as the lower stages usually drop to the ground immediately upon launch. The upper stages that reach orbit typically fire the engine back up after releasing their payloads, directing it back toward an uninhabited area, such as the middle of the ocean.
Crashes sometimes cause unintended unsupervised re-entries, such as The second stage of the SpaceX rocket that fell over Washington State in 2021. But the Falcon 9 stage was smaller, about four tons, and less likely to cause damage or injury.
The United States and NASA have not always been as careful as they are now when returning large objects to the atmosphere.
Skylab, America’s first space station, Fell to the ground in 1979, with great pieces hitting Western Australia. (NASA never paid a $400 fine for littering.)
NASA also didn’t plan to get rid of the Upper Atmosphere Research Satellite, or UARS, after that mission ended in 2005. Six years later, the dead satellite, which was about the size of a city bus, was headed toward an uncontrolled area. Entering, NASA calculated the probability of someone being infected as 1 in 3200. It’s over Falling in the Pacific Ocean.
Ted Mullhaupt, a debris expert at Aerospace Corporation, a federally funded nonprofit that does research and analysis, said 20 to 40 percent of a rocket or satellite will survive re-entry.
That would indicate that 10,000 to 20,000 pounds of the Long March 5B booster could hit the Earth’s surface.
Mr. Muelhaupt said the United States and some other countries avoid uncontrolled re-entry of space debris if the chances of someone on Earth being infected are higher than 1 in 10,000.
So far, there have been no known cases of someone being injured by falling man-made space debris.
“This number is somewhat arbitrary,” said Mr. Muelhaupt. “It’s been so widely accepted, and lately there has been concern about a lot of things coming back in, they add up to the point where someone gets hurt.”
If the stakes are higher, “it’s fairly common for them to be dumped into the ocean,” said Marlon Sorge, executive director of the Aerospace Corporation’s Center for the Study of Orbital Debris and Reentry. “This way, you know you won’t hit anyone.”
Without details of the Chinese missile’s design, Mr. Muelhaupt said, it would not be possible to calculate an estimate of the risks. But, he added, “I am very confident that this is above the threshold” of 1 in 10,000 risks. “Much higher than the minimum.”
The Long March 5B booster is about three times the mass of the UARS. A rough guess would be that it represents three times the risk of 1 in 3200 that NASA estimated for UARS, and possibly higher.
“Those are pretty much three UARs,” said Dr. McDowell. He said the likelihood of someone developing this booster “could be as high as one in a few hundred.”
During a pre-broadcast on CGTN, a Chinese state media outlet, Xu Yansong, a former official with the China National Space Administration, referred to the 2020 incident in Ivory Coast. He has since said, “We’ve improved our technology.” To drop the missile stage in an uninhabited areaAnd the But he did not give details.
The same chain of events could start again soon.
In October, China will launch a second laboratory module called Mengtian into orbit to complete the assembly of Tiangong. It will also fly on another Long March 5B rocket.
You contributed to my research.