A massive Chinese rocket body is expected to fall to Earth this weekend, but that doesn’t mean you should rush into a bunker.
The doomed piece of space junk is the core stage of the Long March 5B rocket which launched a module to China Tiangong Space Station last Sunday (July 24). The latest forecasts indicate that the 25 tonne (22.5 metric ton) booster will arrive on Saturday evening (July 30), although there is quite a large margin of error in these estimates: plus or minus 16 hours at this point. .
Most of the rocket will burn in the earth’s atmosphere, but a significant part of it – about five to nine metric tons (opens in a new tab) (5.5 to 9.9 tons), according to the Aerospace Corporation’s Center for Orbital Reentry and Debris Studies, will make it all the way. However, the chances of a piece hitting anyone are miniscule, considering how much of the Earth is covered by ocean and sparsely populated land.
Related: The biggest spacecraft that fell out of space without control
There’s a “99.5% chance nothing will happen,” said Ted Muelhaupt, a consultant in the office of chief engineer at The Aerospace Corporation, when discussing the upcoming Long March 5B crash that the company streamed live today (July 28) on Twitter.
“Personally, if this fell on my head, I would run outside with a camera to watch it, because I think it would be more of a visual [opportunity] than a real risk,” he added.
The surviving pieces of Long March 5B will travel several hundred miles per hour when they hit the ground (or water). Such impacts will be forceful and destructive, but they will not be cataclysmic.
“The worst-case scenario in this event will be less severe than a single cruise missile strike that we have seen every day in the world. Ukrainian Warso let’s put it in perspective here,” said astrophysicist and satellite tracker Jonathan McDowell, based at the Harvard-Smithsonian Center for Astrophysics, during today’s discussion.
All that said, the upcoming Long March 5B crash is a serious and unfortunate event, McDowell and others pointed out, particularly because it could have been avoided.
The main stages of most orbital rockets are directed to safe demise in the ocean or uninhabited land shortly after liftoff, or, in the case of SpaceX Falcon 9 and Falcon heavy vehicles, descend for vertical landings and possible reuse. The Long March 5B core stage, however, reaches orbit with its payload and remains there until it is knocked down by atmospheric drag.
China’s big rocket now has three launches under its belt, so we’ve already seen two uncontrolled reentries of Long March 5B. One of these falls – after the April 2021 mission that lifted Tianhe, the central stage of the Tiangong space station – happened over the empty ocean. But the other, in May 2020, scattered rocket debris over West Africa, some of which apparently hit the ground in Ivory Coast (opens in a new tab).
As this incident shows, the potential for injury and damage to infrastructure is present in any large uncontrolled event. space debris to fall. And the more such incidents occur, the more likely someone is to be injured or killed.
“You’re not going to win the lottery tonight, but anybody can, and that’s why these stats add up,” Muelhaupt said. “We are doing more, we are indeed putting someone at risk. And it doesn’t have to be. We have the technology, as the old saying goes, to prevent this. We have learned our lessons. We can control the come back.”
China has not fully assimilated these lessons, as evidenced by the design of the Long March 5B. But McDowell expressed optimism that the nation will get on board before too long.
“I see China slowly adopting other countries’ standards in space,” he said. “And I think it’s important to remember that they were sort of a laggard in space activities. And so they’re catching up, and I think they’re catching up with the standards as well.”
Mike Wall is the author of “The low (opens in a 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 a new tab). Follow us on twitter @Spacedotcom (opens in a new tab) Or on Facebook (opens in a new tab).