The day Chinese rocket debris nearly crashed in New York

A few minutes away, the re-entry into the atmosphere of the Long March 5B rocket could have turned into a tragedy. On May 12, the remains of a Chinese heavy launcher have fallen back to Earth at the end of an uncontrolled descent. They flew over the metropolises of Los Angeles and New York before finishing their race about fifteen minutes later in the Atlantic Ocean off West Africa and in certain villages in Côte d’Ivoire where they did not ’caused no casualties.

The rocket had been launched a few days earlier from the Wenchang launch base on Hainan Island, southern China, as part of an experimental flight setting the stage for the country’s upcoming lunar expeditions. After a week in orbit, it returned to Earth and scientists had all the trouble in the world to determine where the first stage of the aircraft was going to land.

Normally, as part of a controlled return to Earth, space debris ends its course in the heart of the Pacific Ocean, in a huge strip of 24 million square kilometers far from all land, known as the point NEMO. Hundreds of aircraft are currently sleeping there, including the Mir station, since 2001.

But in some cases, when a craft has been inactive for a while and ends up out of the control of flight engineers, the descent back to Earth is not controlled. As a specialist on the issue explained to RTL.fr in 2018 on the occasion of the return to Earth of the Chinese space station Tiangong-1, the uncontrolled re-entry of space debris is difficult to model because of the complex dynamics of the upper atmosphere.

“The accuracy of a re-entry corresponds to 10% of the time remaining before re-entry. Ten days before, you can estimate it to be more or less one day. One day, it is fourteen orbits. Ten days before, so you have no idea where it can fall. The day before the start of the school year, you have an accuracy of around 2 hours. 2 hours is 60,000 km “, underlined Christophe Bonnal, expert in space debris at Cnes.

These uncontrolled descents present a limited risk to Earth which is mostly covered with oceans, forests and deserts. Especially since only 10 to 30% of the mass of objects survives their re-entry into the atmosphere. On May 12, most of the first stage of the Chinese rocket disintegrated while plunging towards Earth. Most of its debris was lost at sea, off the coast of West Africa. But several testimonies reported that pieces had been found in Côte d’Ivoire.

A metal pipe about ten meters long , for example, fell on the village of Mahounou which was in the path of the rocket. Local media also reported on a house that had been damaged. An investigation was opened by the local authorities and the Chinese embassy said it was ready to assist the Ivorian authorities in identifying the objects. The episode has most likely ended diplomatically since, like almost all cases of this type.

Not a first

This is not the first time that parts of a Chinese rocket have fallen on populated areas. Remains of launchers are regularly found near Chinese launch sites which are often located in the middle of the land rather than on the coasts. The russian launches, organized from the Baikonur base, also sometimes give rise to falling debris, from the stages of launchers, in the steppes of Kazakhstan. In 2017, an employee tasked with picking up the remains of a fallen rocket was killed in a fire sparked by their fall.

The return to Earth of space debris is much more frequent than we think. One or two large, whole objects enter Earth’s atmosphere every week and disintegrate before hitting the ground. But no direct human victim has not been deplored to this day. In 2011, an American was punched in the shoulder by a piece of metal belonging to a Delta 2 rocket in Oklahoma, but the debris was moving at low speed and she was not injured.

Space waste is also problems for satellites. The space surrounding the Earth is increasingly congested. Tens of thousands of objects orbit our planet and the risk of encountering debris is greater than ever. A space collision could jeopardize nearby satellites and those crossing the area to reach a higher altitude. The International Space Station must also maneuver regularly to avoid obstacles. The European Space Agency plans to send a satellite cleaner to remove such debris within five years.

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