(CNN) The charred remnants of a rocket booster plunged uncontrolled back to Earth Friday morning, an event decried in the West as an irresponsibly risky move by the China National Space Administration.
The rocket reentered the atmosphere over the south-central Pacific Ocean just after 6 a.m. ET, according to the US Space Command, which is part of the Department of Defense.
"Once again, the People's Republic of China is taking unnecessary risks with the uncontrolled rocket stage reentry of their Long March 5B rocket stage. They did not share specific trajectory information which is needed to predict landing zones and reduce risk," said NASA Administrator Bill Nelson in a statement released Friday morning.
"It is critical that all spacefaring nations are responsible and transparent in their space activities and follow established best practices, especially, for the uncontrolled reentry of a large rocket body debris -- debris that could very well result in major damage or loss of life."
This hazardous situation marked the fourth uncontrolled reentry for a Long March 5B rocket since China's space agency started flying it two years ago, as the vehicle was designed without the necessary equipment to steer itself to a safe landing. That fact has repeatedly stirred up controversy and been criticized by space policy experts who say it poses an unnecessary risk.
"I want to point out that the lower the acceptable risk is, the more expensive it is to design to that risk. But it's something that must be done," said Dr. Lael Woods, a space traffic management expert with the Space Safety Institute, during a news conference hosted by The Aerospace Corporation, a federally funded research center.
"Imagine the roads today are completely empty," she continued. "There's really not much need to have rules or stoplights and so on. But we absolutely — with our population that we have driving around on the roads today — we must have stoplights and traffic signs and rules."
The rocket booster is 108 feet (33 meters) end to end, noted Ted Muelhaupt, a space traffic expert and Aerospace Corporation consultant. Much of the hardware will burn up during the fiery reentry process as the 22-metric-ton rocket plunges back into Earth's thick atmosphere, but about 10% to 40% is expected to survive. That's how much debris can make it back into the atmosphere and pose a threat, Muelhaupt said.
A Long March 5B rocket has yet to pose a threat to people. Debris has, however, been found on land. Muelhaupt noted that after one of the boosters crash-landed in 2022, debris was found in Malaysia and the Philippines.
This specific rocket booster was used on an October 31 mission that carried another piece of China's new space station, called Tiangong, to orbit.
Most rockets flying today are built with a means to ensure that rocket boosters are safely discarded. Some companies ensure rockets are steered back toward the ocean. US rocket company SpaceX even manages to guide its first-stage rocket boosters — the largest, bottommost portion of a rocket that gives the initial thrust at liftoff — back to a controlled, pinpoint landing so they can be refurbished and used again.
Muelhaupt noted, however, that equipping a rocket to make such a maneuver is far from trivial. It costs time and development money. The extra equipment also adds mass, and when it comes to trying to escape the crushing pull of gravity and putting precious cargo into space, every pound counts.
Muelhaupt added that he doesn't foresee China attempting to redesign its rocket to add safer landing capabilities, as making that type of adjustment is not trivial.
"it can be really difficult to bring together an entire global community, or even segments of the global community to come to an agreement on what those norms should be and for standards like things like acceptable risk," Woods said. "But while it's really difficult, we believe that establishing international consensus on these norms for behavior involving space is absolutely a worthy and important endeavor."
In a Friday tweet, US Space Command referred questions about the rocket reentry to the government of China, which did not respond to a request for comment from CNN.
At a briefing with China's Ministry of Foreign Affairs (MOFA), however, spokesperson Zhao Lijian referred questions to the department in charge of the rocket booster.
"As a matter of principle, I would like to emphasize that China has always carried out activities for the peaceful use of outer space in accordance with international law and international practice, and it is internationally accepted practice for the upper stages of rockets to re-enter the atmosphere," Zhao said. "The Chinese authorities have been closely monitoring the relevant rocket wreckage orbital parameters. We will release information to the international community in an open and transparent manner and in a timely manner."