Last week, April 29, a Chinese Long March 5B launched the Tianhe module of the Chinese Space Station (CSS), which is expected to be fully operational by 2022. Unfortunately, the rocket that sent that module up into low earth orbit also entered a temporary orbit, meaning it will soon make one of the largest ever uncontrolled re-entries of a space machine, SpaceNews reports.
The European Space Agency stated that the rocket is likely to fall back down to Earth on May 9 at approximately 17:23 UTC, though they say there is a margin of error of approximately one day.
Today, May 4, the rocket is orbiting the Earth approximately once every 90 minutes and is traveling at around 17,149 mph (27,600km/h) and at an altitude of more than 186 miles (300 kilometers).
Experts weigh in on 'unacceptable' Long March 5B re-entry
Jonathan McDowell, Astrophysicist at the Astrophysics Center at Harvard University, told The Guardian that "it's potentially not good. 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."
McDowell also said it was lucky no one got hurt last time. He joins several other experts in warning that large heat-resistant parts of the rocket core have a chance of falling over inhabited areas.
The rocket's current orbit takes it over New York, Madrid, and Beijing, and it could make its re-entry anywhere on its current route.
This morning's data on the altitude-versus-time of the Tianhe / CZ-5B objects. The core stage orbit continues to slowly decay as expected. pic.twitter.com/E8EPJ9yzRu— Jonathan McDowell (@planet4589) May 4, 2021
Separately, McDowell told SpaceNews he thought it was "unacceptable" that the Long March 5B wasn't programmed for a controlled re-entry — he stated that since 1990 nothing over 10 tons has been allowed to make an uncontrolled re-entry due to the risk of damaging property and injuring citizens. The Astrophysicist has made several posts on social media updating on the status of the orbiting object.
As a reference, the Long March 5B core stage currently in orbit is seven times larger than the Falcon 9 second stage — one of which made an uncontrolled re-entry over US soil in March.
As McDowell referenced, it's not the first time a Long March 5B rocket has made an uncontrolled re-entry either. Last May, the NASA administrator at the time, Jim Brindestine, criticized another reentry "that was really dangerous," saying at the time that it was "really fortunate [...] that it doesn’t appear to have hurt anybody."
Long March 5B rocket one of the largest objects ever to make uncontrolled re-entry
Last week's Long March 5B rocket launch was one of 11 missions aimed at constructing China’s CSS space station. The CSS forms part of the country's efforts to bolster its position as the country with the third-largest space program after the US and Russia.
The CSS will weigh approximately 60 tons making it smaller than the International Space Station (ISS), which weighs approximately 408 tons. The ISS launched back in 1998, though it will soon end its operations, with Russia also expected to build its own station by 2025.
In 2019, ESA scientists melted satellite parts on Earth to gain a better understanding of how they burn up on re-entry - their study was conducted in order to better understand the safety risks of human-built space machines on re-entry.
To date, the largest ever uncontrolled re-entry of a space machine happened in 1979 when parts of NASA's Skylab space station fell to Earth, with the US space agency having been unable to pinpoint the exact location at which it would fall to Earth — according to NASA, that space station weighed 100 tons. China's very first space station, the 8.5 ton Tiangong-1, also made an uncontrolled re-entry in 2018.
Stay posted for updates on the Long March 5B's re-entry this week.