Editor's note: China's huge Long March 5B rocket crashed back to Earth Saturday night (May 8) over the Arabian Peninsula. Read our full story of the reentry.
The U.S. Space Command is closely tracking a large Chinese rocket body falling uncontrollably back to Earth that is predicted to hit the atmosphere sometime late Saturday (May 8).
Odds are that the 23-ton (21-metric ton) Long March 5B rocket core booster, will strike an uninhabited area since 70% of Earth's surface is covered in ocean. It's not the largest piece of debris to ever fall uncontrolled back to Earth; NASA's Skylab space station reentry in 1979, for example, was much more massive, at 85 tons (77 metric tons). But the booster's fall comes just over a week after it successfully launched Tianhe, the core module of China's new space station, into orbit.
As of press time, the Long March 5B segment is currently predicted to reenter over the Indian Ocean Saturday night at 11:53 p.m. EDT (0353 GMT) give or take 11 hours, according to the Aerospace Corp., which is tracking the tumbling booster.
From Beijing, foreign ministry spokesperson Wang Wenbin said China is closely tracking the core stage and that most of it would burn up harmlessly in the atmosphere. "The probability of this process causing harm on the ground is extremely low," he said in a Reuters report posted Friday (May 7).
That said, this is the second time in recent memory that a Chinese rocket made an uncontrolled fall; pieces of another rocket in 2020 reportedly slammed into inhabited villages of Côte d'Ivoire, fortunately with no casualties. Even the very slight risk that parts of the 98 feet by 16.5 feet (30 meters by 5 m) object could hit a populated zone is causing observers — military and civilian alike — to pay attention.
There's considerable uncertainty about where and when the stage will hit, since that location depends on the current altitude of Earth's atmosphere (which varies with solar activity), the rocket body's angle when it hits the atmosphere, and the size of pieces that make it through without burning up, among other factors.
"The rocket stage's orbital inclination of 41.5 degrees means that reentry can be as far north as Chicago, New York City, Rome and Beijing and as far south as New Zealand and Chile," Aerospace Corp. wrote on Medium on Thursday (May 6.)
The U.S. military is closely monitoring the situation, along with the White House, both of which have said the issue is a reminder to space-launching nations to take responsibility for space debris after launching things into orbit.
"U.S. Space Command is aware of and tracking the location of the Chinese Long March 5B in space, but its exact entry point into the Earth's atmosphere cannot be pinpointed until within hours of its reentry," the defense branch wrote in a brief statement about the issue.
The statement added that the 18th Space Control Squadron, which monitors orbital debris, is delivering daily updates at space-track.org. "All debris can be potential threats to spaceflight safety and the space domain, and the 18th SPCS delivers front-line space defense and warnings to the global space community," officials wrote in the statement.
In a briefing with reporters on Thursday (May 6), U.S. Secretary of Defense Lloyd Austin said the department has no plans to shoot down the space debris, the way officials did during a test exercise with U.S. military satellite USA-193 (also known as NROL-21) in 2008.
"We don't have a plan to shoot the rocket down," Austin said, according to a transcript. "We're hopeful that it will land in a place where it won't harm anyone, hopefully in the ocean or someplace like that. I think this speaks to the fact that for those of us who operate in the space domain, there … should be a requirement to operate in a safe and thoughtful mode, and make sure that we take those kinds of things into consideration as we plan and conduct operations."
When asked if the U.S. military even has the capability to bring the satellite down, Austin added: "We have the capability to do a lot of things, but we don't have a plan to shoot it down, as we speak."
Amateur skywatchers are also keeping an eye out for the rocket, with the Virtual Telescope's Gianluca Masi planning to broadcast live footage from Rome late tonight if the core stage is visible. That webcast is scheduled for 10:40 p.m. EDT (0240 GMT) May 7, weather permitting. You can watch it directly from the Virtual Telescope here and on YouTube.
Follow Elizabeth Howell on Twitter @howellspace. Follow us on Twitter @Spacedotcom and on Facebook.