Wednesday, May 05, 2021

Chinese rocket “could hit inhabited area” on Earth

The sky is certainly not falling, as Chicken Little might have warned. But there is a risk, albeit a small one, that debris from a Chinese space rocket could impact on an inhabited place on Earth in the coming days.

The object of concern is a 22 metric tonne part of the Chang Zheng 5 rocket that was use to launch the first part of China's new space station into orbit.

The Long March 5B Chinese rocket launched a module of the country's space station on 29th April but the rocket's core is falling out of Earth's orbit and is expected to make an uncontrolled re-entry this week. And many experts fear it could land on an inhabited area.

"It's potentially not good," said Jonathan McDowell, Astrophysicist at the Astrophysics Center at Harvard University. "Last time they launched a Long March 5B rocket they ended up with big long rods of metal flying through the sky and damaging several buildings in the Ivory Coast," he said. "Most of it burned up, but there were these enormous pieces of metal that hit the ground. We are very lucky no one was hurt."

This piece of space junk is of bigger concern however given both its size and weight, and also because it's unlikely to burn up as it falls to Earth.

On Tuesday the core was orbiting Earth around every 90 minutes at about 27,600 km/h at an altitude of more than 300km. The US military has named it 2021-035B and has added it to the list of some 27,000 pieces of space it tracks daily. You can track 2021-35B here:

It is highly likely the remnants of Chang Zheng 5 will simply crash into the sea, given the vast expanse of ocean it passes over. Indeed the chance of being hit by China's space junk is said to be one in a trillion, and obviously zero if living outside its current path of orbit. Nonetheless, the spent rocket does pass over parts of the US, South America, Africa, Spain, the Middle East, India, China and Japan.

There are worst case scenarios, such as landing on a nuclear power station or similar facility. And there are concerns its landing in a highly populated could kill and injure dozens if not hundreds of people.

These possibilities are of course slim. But McDowell says some pieces of the rocket will survive re-entry and that it would be the "equivalent of a small plane crash scattered over 100 miles".

Since 1990 nothing over 10 tonnes has been deliberately left in orbit to re-enter uncontrolled. And it is not the first time a large piece of Chinese space junk has crashed back down to Earth. In 2018 China's defunct space lab, Tiangong-1, came crashing down into the Pacific Ocean [BBC].

"It's really negligent on China's part,"  McDowell said, "Things more than ten tonnes we don't let them fall out of the sky uncontrolled deliberately."

It is expected to crash back to Earth on Saturday 8th May 2021, but while a Department of Defense spokesperson revealed the date of its expected reentry into Earth's atmosphere, its exact entry point can't currently be determined.

Even if Saturday passes off uneventfully there might be further concerns in the future as the launch was just the first of 11 missions needed to complete China's upcoming space station, intended to rival the ISS.

[BBC / CNNGuardian / Daily Mail / Space News]

tvnewswatch, London, UK

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