A huge piece of Chinese space junk is expected to crash back to Earth on Friday (November 3), but no one knows exactly where or when it will come down.
The debris in question is the 23-tonne (21 metric tons) core stage of a Long March 5B rocket, which reached Earth orbit on Monday (October 31) following the launch of the third and final module for China’s Tiangong space station.
Atmospheric drag pulls the rocket body lower and lower since then. The latest observations and models suggest that Long March 5B will descend on Friday morning, but the error bars on that prediction remain wide for now.
The Aerospace Corporation, for example, predict (opens in new tab) an atmospheric re-entry on Friday at 7:20 a.m. EDT (1120 GMT), plus or minus three hours. This large window puts part of North America, nearly all of Central America, much of Africa and a chunk of southeastern Australia, among other areas, in the potential line of fire for falling space debris.
Related: The latest news on China’s space program
Our latest re-entry forecast for rocket body #CZ5B is:🚀04 Nov 2022 11:20 UTC ± 3 hours Re-entry will be along one of the ground tracks shown here. It is still too early to determine a substantial debris footprint. Follow here for updates: https://t.co/KZZ9LgLk0k pic.twitter.com/GlnE8C0IokNovember 3, 2022
We’ve been through this embarrassing exercise before. The March 5B’s long core stages have fallen to Earth uncontrollably in all three of the vehicle’s previous launches, most recently in July after the rocket sent the Wentian module to Tiangong.
Indeed, this is a (rather unwanted) feature of the Long March 5B. Other orbital rockets are designed so that their first stages fall into the ocean or uninhabited land shortly after launch or, in the case of SpaceX’s Falcon 9 and Falcon Heavy, fall in one piece for engine landings and future reuse. But the Long March 5B core stage reaches orbit and has no way of steering itself, so it lets atmospheric gravity do the work, messily.
Although much of the rocket’s body will burn up in the atmosphere when it falls on Friday, some of the most durable pieces will survive to the ground, endangering people and infrastructure on the re-entry path.
“The general rule is that 20-40% of the mass of a large object will reach the ground, but the exact number depends on the design of the object,” The Aerospace Corporation wrote in an explanation of the Long March 5B. (opens in new tab). “In this case, we would expect about 5 to 9 metric tons [5.5 to 9.9 tons].”
Space-based sensors using HEO Inspect caught the #CZ5B rocket as it continues its uncontrolled re-entry back to Earth. Our space-to-space imagery and intelligence support strategic decision-making and accountability efforts by making space transparent. Powered by @Satellogic pic.twitter.com/kPZfSypFlANovember 3, 2022
The odds dictate that such debris will likely fall into the ocean, as seas cover about 70% of the Earth’s surface. But terra firma has welcomed Long March 5B debris before. For example, rocket debris from the first Long March 5B launch, in May 2020, apparently fell to the ground (opens in new tab) in a village in the West African nation of Ivory Coast.
No one was injured in this incident, or any of the other Long March 5B accidents, as far as we know. But the fact that falling rocket bodies pose any risk, however small, has drawn condemnation from exploration advocates and other members of the spaceflight community.
“Spacefaring nations must minimize risks to people and property on Earth from re-entries of space objects and maximize transparency about these operations,” NASA Administrator Bill Nelson wrote in a statement. (opens in new tab) published shortly before the crash of Long March 5B in May 2021.
“It is clear that China is failing to meet responsible standards regarding its space junk,” he added. “It is critical that China and all space nations and commercial entities act responsibly and transparently in space to ensure the safety, stability, security and long-term sustainability of space activities.”
Mike Wall is the author of “Out there (opens in new tab)” (Grand Central Publishing, 2018, illustrated by Karl Tate), a book about the search for extraterrestrial life. Follow him on Twitter @michaeldwall (opens in new tab). Follow us on Twitter @Spacedotcom (opens in new tab) or up Facebook (opens in new tab).