World awaits Chinese rocket to reenter the atmosphere, not knowing where it will land

The Long March-5B rocket is projected to reenter the Earth's atmosphere at about 18,000 mph between 11 p.m. Saturday and 5:30 a.m. Sunday Eastern, according to space agencies and experts. At around 100 feet tall and about 22 metric tons, the rocket stage is set to become one of the largest objects to ever reenter the Earth's atmosphere on an uncontrolled trajectory.

Where the rocket will land remains unclear. Scientists have said the risk to humans is astronomically low, but it is not impossible for it to land in a populated area. The Aerospace Corporation, a nonprofit largely financed by the U.S. government, predicted Saturday that it would splash down in the Atlantic Ocean, with the closest countries being Portugal and Spain.

But the rocket could reenter at anywhere between 41.5 degrees north latitude and 41.5 degrees south latitude, meaning major cities like New York could be hit with debris. The European Space Agency has predicted a "risk zone" that encompasses much of the world, including nearly all of the Americas, all of Africa and Australia, parts of Asia and the European countries like Italy and Greece.

China has been criticized for its handling of the rocket booster, which was launched into space on April 29 to ferry the first module of the Tianhe space station. China did not make the necessary preparations for a controlled reentry, which would have slowed the rocket enough to enter Earth's atmosphere over a predetermined remote area or ocean, thus reducing the chance of debris impacting populated regions.

Astrophysicists have described China's decision as potentially hazardous corner-cutting. "There's clearly a significant chance that it's going to come down on land," Jonathan McDowell, an astrophysicist at the Harvard-Smithsonian Center for Astrophysics, told CNN on Saturday.

China's state media, however, has reacted angrily to the international scrutiny, saying its launch was being unfairly maligned. State media slammed U.S. media outlets for covering China's "out-of-control space junk" in contrast to the SpaceX wreckage.

Chinese Foreign Ministry spokesman Wang Wenbin defended the plan as "standard international practice," saying at a news conference this week that "China is always committed to the peaceful use of outer space," according to state media.

"China is ready to work with all relevant parties to make joint efforts for the peaceful use of outer space and safeguarding space security," Wang said.

The size of the rocket makes its reentry more unpredictable than others. Most satellites and other man-made objects are small enough to burn up in the atmosphere. But the Long March booster is much larger, raising concern that pieces could survive and hit the ground.

The rocket's tumbling motion as it passes through the mesosphere, an outer layer of Earth's atmosphere, has also made calculations of its speed tricky to project.

Space has been a point of national pride for China, which is expected to run the only operational space station after the retirement of the International Space Station in the next four years. The country, which has spoken of putting people back on the moon, has completed a flurry of successful lunar and Mars missions in recent years.

But China's growing space program has contributed to the growing problem of space debris. The Secure World Foundation, a think tank, said that China in 2007 "created a cloud of more than 3,000 pieces of space debris" after the country shot down a dead satellite with a missile.

During the first flight of the Long March 5B rocket last year, the booster passed over populated portions of Earth before pieces of debris landed in Africa. Jim Bridenstine, the NASA administrator at the time, slammed the Chinese space agency for the booster's return, saying the event "could have been extremely dangerous."