For the fifth time in less than three years, a massive Chinese rocket stage is expected to plunge to Earth, perhaps as soon as Friday.
But several of those tracks pass over a large swath of the Earth’s populated areas, meaning there’s still the possibility of someone being injured by the rocket’s return. And that raises another question: Why does China, alone among space-faring nations, allow the unplanned return of its boosters, instead of ditching them at sea, as most others do, or returning them to a soft landing, like Space X?
NASA Administrator Bill Nelson has repeatedly condemned China for its behavior. In a statement last year, he said the Chinese were acting irresponsibly. “Spacefaring nations must minimize the risks to people and property on Earth of re-entries of space objects and maximize transparency regarding those operations,” he said. “It is clear that China is failing to meet responsible standards regarding their space debris.”
“The technology exists to prevent this,” said Muelhaupt. The rest of the world doesn’t “deliberately launch things this big and intend them to fall wherever. We haven’t done that for 50 years.”
The booster of China’s massive Long March-5B rocket stays aloft for several days after launch and then comes crashing back to Earth, tumbling out of control. This one was launched Monday, carrying the final module of the Tiangong space station that China is assembling in Earth’s orbit.
As of Wednesday, the Aerospace Corporation’s calculations had the stage possibly landing over areas of land where 88 percent of the world’s population lives. And so the possibility of casualties, Muelhaupt said, is between one in 230 to one in 1,000. That risk far exceeds the internationally recognized standard that says a reentering space object should not have greater than a one in 10,000 chance of causing injury.
The Chinese rocket stage is massive — weighing 22 metric tons and measuring as long as a pair of 53-foot semitrailers parked end to end, Muelhaupt said. He estimates that between 10 and 40 percent of the booster will survive reentry and hit the Earth.
After a launch of the Long March-5B in May 2020, a piece of the rocket landed in the Ivory Coast in Africa. In July, debris fell in Indonesia and Malaysia. Chinese Long March rockets are the third, fourth, fifth and sixth largest uncontrolled re-entries ever into Earth’s atmosphere, he said.
NASA has gone to great lengths to ensure the expendable core stage of its Space Launch System rocket falls into the Atlantic far from people, Jim Free, NASA’s associate administrator for exploration systems development, told reporters Thursday. “We have very clear direction to safely dispose of what we put in orbit,” he said. “That is core to what NASA does.”
Russian boosters fall in designated areas of Kazakhstan and Russia that are unpopulated.
Getting other nations to behave responsibly, however, remains a problem. While the nations launching objects to space are liable if they cause injury or damage on the ground, there are no laws that prohibit nations from letting large pieces of debris crash to Earth.
“The reality is that there aren’t any real laws or treaties internationally that govern what you’re allowed to do in terms of reentry,” said Marlon Sorge, a technical fellow at the Aerospace Corporation. “So, there isn’t really a direct legal way to control what’s going on an international level.”
In other words, there are few, if any, rules to the road that govern space. Instead, there are efforts underway by the Aerospace Corporation, and others to create standards that countries with space programs would adhere to.
“While it’s really difficult, we believe that establishing an international consensus on these norms for behavior involving space is absolutely a worthy and important endeavor,” said Lael Woods, a space traffic management expert at the Aerospace Corporation.
Meantime, space is littered with all sorts of debris, including upper stages from rockets that can stay in orbit for months, even years. While many burn up when they fall through the atmosphere, some survive, at least in part.
Earlier this year, for example, a part of a SpaceX’s booster landed in Australia, where it was found by a sheep farmer.
“Pretty frightening, actually,” Mick Miners, told the New York Times. “I was quite surprised. It’s not something you see every day on a sheep farm.”