Parts of China's Giant Long March 5B Rocket May Be Set to Plummet to Earth

It is feared debris from China's recent rocket launch, the Long March 5B, will crash back to Earth at an unknown location.

The rocket was launched on July 24 from the Wenchang launch site in Hainan province, carrying the Wentian experiment module, a new solar-powered lab, to China's Tiangong Space Station. Due to its large size, there are concerns that not all of the ejected first-stage rocket will burn up in the atmosphere as it falls, instead, crash landing somewhere on the planet.

Normally, after a rocket uses up all the fuel in its first stage, the empty part is ejected to remove the extra weight, falling to Earth. Usually, these parts burn up as they hit the atmosphere at high speeds.

Long March 5B
Stock image of a Long March 5B rocket launching Wenchang launch site on China's southern Hainan island on May 5, 2020. The first rocket stage debris from a recent launch is expected to crash land in unpredictable locations. STR/AFP via Getty Images

The Long March 5B is very large, however: it measures 176 feet tall, and weighs more than 1.8 million pounds.

"It will break up, but past experience shows that a bunch of 30-meter-long [100 foot] metal fragments will end up crashing into the ground at a few hundred km/hr," said Jonathan McDowell, an astronomer at the Harvard-Smithsonian Center for Astrophysics, in a tweet.

The larger the spacecraft, the larger the number of chunks of space debris falling back into the atmosphere, especially those made of heat-resistant materials.

"It is always difficult to assess the amount of surviving mass and number of fragments without knowing the design of the object, but a reasonable "rule-of-thumb" is about 20-40 percent of the original dry mass," Holger Krag, head of the Space Safety Program Office for the European Space Agency, told SpaceNews.

The location of the landings is very hard to predict, especially at the moment, as solar activity has caused atmospheric fluctuations that complicate the modeling of the flight path. The speed of the process of orbital decay also depends on the size and density of the objects.

Once we know the precise measurements and angle of the rocket's orbit, we should be able to more accurately predict when and where the debris will fall, according to tweets by McDowell.

The chances of the debris hitting an inhabited area are very low: NASA has estimated that the odds of a person being hit by a piece of space debris are around 1 in 3,200.

However, due to the increase in space junk in Earth's orbit, the chances of pieces of debris falling from the sky is increasing, especially in the Global South, according to research published in the journal Nature Astronomy.

There are up to 27,000 smaller pieces of debris being tracked by NASA, clogging up the orbit zone and traveling at up to 15,700 mph in low-Earth orbit.

Rockets can be designed to be actively deorbited, so that they can land in a specific area where there is no chance of injury or damage to property. In the wake of this predicted uncontrolled debris fall from the Long March 5B, a similar event last year where a Chinese rocket core stage fell into the Indian Ocean, and another in 2020 where debris including a 40-foot pipe fell onto two villages in the Ivory Coast and damaged several buildings, NASA has called out China's risk management.

NASA administrator Bill Nelson said that China was "failing to meet responsible standards regarding their space debris." However, China doesn't agree, and in response to the 2021 Indian Ocean debris incident, the Chinese foreign ministry said that the likelihood of damage was "extremely low."

According to the authors of the Nature Astronomy paper, these risks are preventable.

"Launch providers have access to technologies and mission designs today that could eliminate the need for most uncontrolled re-entries," they said.

"On the issue of uncontrolled rocket body reentries, the states of the Global South hold the moral high ground: their citizens are bearing most of the risks, and unnecessarily so, since the technologies and mission designs needed to prevent casualties exist already."