(Illustration: The U.K. and France as seen from the Space Station, and found here).

Just when you thought it was safe to go outside again, or maybe even stay inside, depends on the chance:

Heads up. Huge rocket looks set for uncontrolled reentry following Chinese space station launchhttps://t.co/tERfS2lFY9

— Andrew Jones (@AJ_FI) April 30, 2021

Details via SpaceNews on Friday:

China launched the first module for its space station into orbit late Wednesday, but the mission launcher also reached orbit and is slowly and unpredictably heading back to Earth.

The Long March 5B, a variant of China’s largest rocket, successfully launched the 22.5-metric-ton Tianhe module from Wenchang Thursday local time.
Tianhe separated from the core stage of the launcher after 492 seconds of flight, directly entering its planned initial orbit.

Designed specifically to launch space station modules into low Earth orbit, the Long March 5B uniquely uses a core stage and four side boosters to place its payload directly into low Earth orbit.

However this core stage is now also in orbit and is likely to make an uncontrolled reentry over the next days or week as growing interaction with the atmosphere drags it to Earth.
If so, it will be one of the largest instances of uncontrolled reentry of a spacecraft and could potentially land on an inhabited area.
…
Ground based radars used by the U.S. military to track spacecraft and other objects in space have detected an object and catalogued it as the Long March 5B rocket body.
Now designated 2021-035B, the roughly 30-meter-long, five-meter-wide Long March 5 core stage is in a 170 by 372-kilometer altitude orbit traveling at more than seven kilometers per second.

A possible amateur ground observation of the rocket core showing regular flashes suggests that it is tumbling and thus not under control.
…
Where and when the new Long March 5B stage will land is impossible to predict.
The decay of its orbit will increase as atmospheric drag brings it down into more denser. The speed of this process depends on the size and density of the object and variables include atmospheric variations and fluctuations, which are themselves influenced by solar activity and other factors.

The high speed of the rocket body means it orbits the Earth roughly every 90 minutes and so a change of just a few minutes in reentry time results in reentry point thousands of kilometers away.

The Long March 5B core stage’s orbital inclination of 41.5 degrees means the rocket body passes a little farther north than New York, Madrid and Beijing and as far south as southern Chile and Wellington, New Zealand, and could make its reentry at any point within this area.

The most likely event will see any debris surviving the intense heat of reentry falling into the oceans or uninhabited areas, but the risk remains of damage to people or property.

Further particulars from Gizmodo, also from Friday:

Jonathan McDowell, an astrophysicist at the Harvard-Smithsonian Center for Astrophysics, suspects this is a deliberate design choice.

“Both CZ-5B launches have left their core stage in orbit for uncontrolled reentry,” he explained in an email. “They are over 20 [metric tons]. It has been standard practice for 30 years for the rest of the world not to leave objects this big—or even half this big—in orbit without controlled deorbit.”

To which he added: “This design choice in 2021 is unacceptable and tarnishes China’s great achievement in launching Tianhe.”

Heads up, for sure  — and speed-up reentry just to be on the safe side, Sandra:

As one commentator noted: ‘An American astronaut in a Russian suit riding a Chinese Space ship...’

(Illustration: Salvador Dali’s ‘Baby Map of the World,’ found here)