Debris from April 29 launch set to plunge back through the atmosphere in the next few hours.
Remnants of China’s largest rocket, launched last week, are expected to plunge back through the atmosphere in the coming hours, according to tracking centres in Europe and the United States.
The 18-tonne main segment of the Long March-5B rocket that launched the first module of China’s new space station into Earth’s orbit on April 29 is now in freefall and experts have said it is difficult to say precisely where and when it will re-enter the atmosphere.
China’s foreign ministry said on Friday that most debris would burn up on re-entry and was highly unlikely to cause any harm.
“The probability of causing harm … on the ground is extremely low,” Chinese foreign ministry spokesman Wang Wenbin told reporters.
US Space Command estimated re-entry would occur at 02:11 GMT on Sunday, plus or minus one hour, while the Center for Orbital Reentry and Debris Studies (CORDS) at Aerospace Corporation, a US federally funded space-focused research and development centre, updated its prediction to two hours either side of 03:02 GMT with the rocket re-entering over the Pacific.
EU Space Surveillance and Tracking (EU SST) said its latest prediction for the timing of the re-entry of the Long March 5B rocket body was 139 minutes either side of 02:32 GMT on Sunday.
EU SST said the statistical probability of a ground impact in a populated area is “low”, but noted that the uncontrolled nature of the object made any predictions uncertain.
Space-Track, reporting data collected by US Space Command, estimated the debris would make re-entry over the Mediterranean Basin.
Visitors walk through a model of China’s Tianhe space station at an exhibition on the development of China’s space exploration last month [Tingshu Wang/Reuters]Travelling at a speed of approximately 4.8 miles (13.7km) per second, a difference of just one minute in the time of re-entry translates to hundreds of miles difference on the ground.
“This is difficult to predict and not an exact measurement,” Space-Track wrote on Twitter.
The Long March 5B – comprising one core stage and four boosters – lifted off from China’s Hainan island on April 29 with the unmanned Tianhe module, which contains what will become living quarters on a permanent Chinese space station.
The rocket is set to be followed by 10 more missions to complete the station.
Most experts believe the risk to people is low.
“Given the size of the object, there will necessarily be big pieces left over,” said Florent Delefie, an astronomer at the Paris-PSL Observatory.
“The chances of debris landing on an inhabited zone are tiny, probably one in a million.”
In May 2020, pieces from the first Long March 5B fell on Ivory Coast, damaging several buildings. No injuries were reported.
Debris from Chinese rocket launches is not uncommon within China. In late April, authorities in the city of Shiyan, Hubei Province, issued a notice to people in the surrounding county to prepare for evacuation as parts were expected to land in the area.
“The Long March 5B reentry is unusual because during launch, the first stage of the rocket reached orbital velocity instead of falling down range as is common practice,” the Aerospace Corporation said in a blog post.
“The empty rocket body is now in an elliptical orbit around Earth where it is being dragged toward an uncontrolled re-entry.”
The empty core stage has been losing altitude since last week, but the speed of its orbital decay remains uncertain due to unpredictable atmospheric variables.
It is one of the largest pieces of space debris to return to Earth, with experts estimating its dry mass to be approximately 18 to 22 tonnes.
The core stage of the first Long March 5B that returned to Earth last year weighed nearly 20 tonnes, surpassed only by debris from the Columbia space shuttle in 2003, the Soviet Union’s Salyut 7 space station in 1991, and NASA’s Skylab in 1979.