The 21-ton Long March 5B rocket carried a module of China’s new space station into low Earth orbit last week.
But the 30-meter long rocket itself also reached orbit and will now become one of the largest ever launchers to make an uncontrolled reentry, according to SpaceNews.com
Experts say that most expendable rockets do not reach a velocity that would take them into orbit and they normally reenter the atmosphere and land in a known reentry zone.
The speed of the rocket means it is orbiting the Earth every 90 minutes and it is passing just north of New York, Madrid and Beijing, and as far south as Chile and Wellington, New Zealand.
It is most likely that any debris not burned up on reentry will land in the ocean or an uninhabited area, but “the risk remains of damage to people or property,” according to SpaceNews.
Last May the first launch of Long March 5B also saw the first stage reach orbit and it had an uncontrolled reentry six days later.
The US military said it reentered over the Atlantic Ocean but had it happened 15 to 30 minutes earlier any debris not burning up would have hit US soil.
Spaceflight observer Jonathan McDowell said that the size of the rocket means it would be an unprecedented reentry.
“The Long March 5B core stage is seven times more massive than the Falcon 9 second stage that caused a lot of press attention a few weeks ago when it re-entered above Seattle and dumped a couple of pressure tanks on Washington state,” he told SpaceNews.
“I think by current standards it’s unacceptable to let it re-enter uncontrolled.
“Since 1990, nothing over 10 tons has been deliberately left in orbit to re-enter uncontrolled.”
Items that can survive reentry include components made of heat resistant materials, such as stainless steel or titanium tanks.
China is aiming to complete its Tiangong Space Station by 2022 following the launch of the remaining modules.