Luna  China's rocket stage finally crashed in the Indian Ocean

Luna China’s rocket stage finally crashed in the Indian Ocean

A large part of the Earth is relieved: this Saturday, July 30, a whole stage of the rocket will “return to the Earth’s atmosphere” (read: it will crash). A few hours before the crash, we still don’t know where it will fall exactly on our planet. The 22-ton machine finally “returned” at 6:45 pm, over the Indian Ocean. The exact drop point and impact size of the debris is still unknown.

On Twitter, a man tweeted a video from Kuching, Malaysia showing the dispersal of the craft.

A rocket that took off on July 24 from China

On Sunday July 24, China launched the second of three space station modules under construction. The machine named Wentian, about 20 tons and without an astronaut on board, was launched by a Long March 5B rocket from the Wenchang launch center on the tropical island of Hainan (southern). Nearly 18 meters long and 4.2 meters in diameter, this laboratory module landed on Tianhe, the first module of the station to be in orbit since April 2021.

Problem: A 22-ton rocket stage carrying Wentian will fall back to Earth after nearly a week in orbit. And no specialist could say where exactly. According to the Aerospace Corporation, of the 22 tons, “only” 5 to 9 tons will actually crash on our planet, with the rest burning up upon entering the atmosphere.

An “uncontrollable” return

According to the Aerospace Corporation, the crash is estimated in a long corridor from California to Japan through South America and South Africa.

Usually, the “return to the atmosphere” is “controlled”, that is, the directions and trajectories are calculated so that the device crashes, usually, in the sea. For example in 2001, the Mir orbital station had a “return” in a controlled manner after 15 years in space. 135 tons ended up in the Pacific Ocean, near the Fiji Islands.

As for this Long March 5B (LM5B) rocket stage, it is a mystery. For the last rockets sent into space, the big stages separated immediately after takeoff, in the sea. This is an international standard, which is not respected by China. SpaceX has even made stages that can be reused later. But LM5B will reach orbit, then circle the Earth until the gravity of the atmosphere takes effect.

Impossible calculations

Why is it so hard to find more? Because the machine rotates the Earth at 27,400 km / h. And that everything will change depending on the exact moment he begins his descent. A one-hour difference in atmospheric entry represents a difference of 27,350 km.

Also, the engine doesn’t work in a “straight” way either, it turns in all directions. And the density of the upper layer of the atmosphere varies. “This makes it impossible to predict when the satellite will spend enough time on it to start melting and self-destruct, before falling back”, decrypted Jonathan McDowell, from the Aerospace Corporation.

Although the countries of this corridor are trembling, scientists want to be reassured: “there is a 99.5% chance that nothing will happen”, the Aerospace Corporation continues. Which seems to have happened.

However, it is necessary to consider the main engine but also its remnants. In May 2020, the stage of an LMB5 crashed into the sea, but its wreckage was widely seen in West Africa. Regardless, this Saturday night, many people were happy to know that the sky did not fall on their heads.

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