China claims space junk will land in international waters as US watches on

Chinese media says space junk will land in international waters when it makes its re-entry into Earth's atmosphere this weekend.

The claims, published in Global Times, a daily tabloid run by the Chinese Communist Party, say reports the Long March 5B rocket is "out of control" and could land in an inhabited area are "hype".

The Global Times said the situation is "not worth panicking about".

The article claimed the debris was likely to "burn up during re-entry … leaving only a very small portion that may fall to the ground, which will potentially land on areas away from human activities or in the ocean".

It comes as the US Pentagon said the US Secretary of Defence Lloyd Austin was aware of the situation, and tracking the rocket's trajectory on Wednesday.

The Pentagon believes it will re-enter Earth's atmosphere on Saturday, US time (Sunday in Australia).

The debris is believed to weigh several tonnes, and could crash to Earth in the coming weeks, Steve Freeland wrote for The Conversation.

Professor Freeland said because of the Earth's orbit, it's difficult to predict where the objects will land, and it could be anywhere within a band of latitudes "a little farther north than New York, Madrid and Beijing, and as far south as southern Chile and Wellington, New Zealand".

The body of the rocket "is almost intact coming down," Pentagon spokesman John Kirby said.

Kirby said it is "too soon" to know whether any action, such as destroying the space debris, can be taken if human-occupied regions are threatened.

"We're tracking it. We're following it as closely as we can," he said.

"It's just a little too soon right now to know where it's going to go or what, if anything, can be done about that."

The April 29 launch was the first of three elements of the planned Chinese space station, CSS, powered by the Long March 5B rocket.

Predictions of re-entry nearly impossible

After its separation from the space station module, the rocket began to orbit Earth in an irregular trajectory as it slowly lost altitude.

These movements mean making predictions about how the junk will fall to Earth are nearly impossible.

It could end up breaking apart upon entry, with only smaller pieces of debris making impact. Experts also note if the rocket falls from the sky mostly intact, there is a good chance it will just splash down into the ocean, as the planet is 70 per cent water.

But neither of those outcomes is certain, and there is a chance the rocket could crash into an inhabited area, or hit a ship.