When you’re asked “What’s up?” this weekend, here’s your answer: Long March 5B, a roughly 44,000-pound rocket body spiraling toward Earth.
But scientists aren’t sure when or where that debris is from China’s launch last Sunday on its Wentian space station module — will land. The Aerospace Corporation has released its latest predicted paths for the debris – with the disclaimer that it’s still too early to be certain.
Experts estimate that 20 percent to 40 percent of the rocket’s massive body mass will survive its fiery journey through Earth’s atmosphere to the planet’s surface, but not all of it. Seventy percent of the planet is covered by ocean, so chances are whatever’s left of the rocket will land in water, but that’s not guaranteed.
Shrugging at the potential dangers of Long March 5B debris is nothing new. Aaron Bowley, co-director of the Space Institute and a planetary astronomer at the University of British Columbia, said about 70 percent of rockets that exit orbit and re-enter Earth’s atmosphere do so in an uncontrolled manner, and rocket debris is only a fraction of this risk.
In April, a 6- to 10-foot metal ring fell on a village in the Indian state of Maharashtra. In 2020, a 39-foot metal pipe landed on two villages in Côte d’Ivoire. In 2016, two rocket fuel tanks landed on islands in Indonesia. Earlier this month, parts of a SpaceX cargo capsule fell into paddocks in New South Wales, Australia.
“Every time we launch missiles, we’re rolling dice,” Bowley said. “And the problem is, we roll a lot of dice, a lot of times.”
Rockets are the transport vessels for everything launched into orbit, including individual satellites and satellite constellations, telescopes, engineering projects and research modules. In 2021, there were more than 130 successful launches of orbital rockets worldwide — a record — and 2022 is on track to achieve even more as space development soars.
“In the future, we may have companies launching rockets to build their own space stations, whether it’s tourism or manufacturing in orbit,” Bowley said.
Missile trajectories can take several forms. Often, they gradually disintegrate during ascent, releasing heavy boosters or empty fuel tanks in a controlled process called a stage. When the stage occurs in the suborbital zone—where Earth’s gravity still has full or near-full effect on the dropped machines—launch teams can precisely plan where they will land (over an ocean).
Other mission paths require some rocket stages to be abandoned in low Earth orbit (LEO) — a region believed to be between 180 and 1,250 miles above Earth — where they are left to drift, effectively, as space junk. .
The technology is there to limit the danger. It’s just that not everyone uses it.
This is not a technological problem. Some rockets, like SpaceX’s Falcon 9, have re-ignition engines that can direct re-entry to an uninhabited (human) place on Earth, and sometimes even complete return trips with landing pads ready and waiting.
But not all rockets are equipped with these technologies, and even if they are, “there are additional costs associated with recovery,” Bowley said. “The customer may choose a cheaper option, or the launch team may decide it’s easier to get the object into orbit.”
So the rocket hulls – including the particularly massive Long March 5B, which is not equipped with re-ignition engines – are left to litter LEO. This is a policy decision that many countries, including the US, seem to be okay with.
Over 1,000 rocket bodies and thousands of satellites currently fly through LEO, completing orbits around Earth every 90 to 120 minutes.
Gradually, these slow-burn orbital journeys—tracked most prominently and shared online by the Aerospace Corporation, an independent, government-sponsored nonprofit organization—are slowed by drag, the same aerodynamic force that naturally opposes an airplane or race car, and fall toward The Earth.
“It’s all kind of funny, because an orbit is nothing more than falling towards something and constantly missing. And then eventually the gas resistance makes it so, no, it’s going to hit this time.
Where space debris falls is not always left to chance
The eventual landing sites for many of these uncontrolled incursions are not always random – with many launching and landing around the equator.
In studying the orbital trajectories of more than 1,500 rockets that have gone out of orbit over the past 30 years, Bowley and a team of researchers at the University of British Columbia estimated that there is between a 10 and 20 percent chance of casualties due to rocket debris.
That’s a far cry from the 0.01 percent risk threshold the United States applies to its launches, a casualty estimate that is often dismissed. “To my knowledge, there is no paper trail of the decision-making process that led to this [0.01 percent] the number is applied to launches and re-entries,” Bowley said.
“But we can’t paint space people as bad guys,” said Timiebi Aganaba, an assistant professor and senior global futures scientist at Arizona State University who specializes in environmental and space management. “[When the policies on space development were set], there were so few launches; it’s just not something 10 years ago anyone would have talked about.”
But now, as space continues to become a commodity and rockets fly more frequently, both Bowley and Aganaba agree that rocket debris is a problem for collective action. Bowley said the decision would require the international community to come together and agree on regulations to reduce risk.
How and when these rules will be made and followed remains to be seen. It could take until “someone wins the lottery, so to speak,” to unfortunately get hit by space debris, Bowley said. “Chances are it won’t be you, but someone will.”
This article has been updated. Thanks to Lillian Barkley for editing this article.
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