A 22-ton Chinese rocket falls back to Earth. Where will he land?

When someone asks you “What’s up?” this weekend, here’s your answer: Long March 5B, a roughly 44,000-pound rocket body heading for Earth.

But scientists don’t know when or where that debris – since China’s launch last Sunday of its Wentian space station module — will land. The Aerospace Corporation has released its latest predicted trajectories for the debris – with the warning that it is still too early to be certain.

Experts believe that 20-40% of the rocket body’s immense mass will survive its fiery journey through Earth’s atmosphere to the planet’s surface, but not in one piece. Seventy percent of the planet is covered in ocean, so there’s a good chance that whatever’s left of the rocket will land in water, but that’s not guaranteed.

The shrugs in response to the potential dangers of the Long March 5B debris are nothing new. Aaron Boley, co-director of the Outer Space Institute and planetary astronomer at the University of British Columbia, said about 70% of rockets that leave orbit and re-enter Earth’s atmosphere do so uncontrollably. , and rocket debris is just part of that risk.

In April, a 6-10ft metal ring fell on a village in the Indian state of Maharashtra. In 2020, a 39ft metal pipe landed on two villages in Ivory Coast. In 2016, two rocket fuel tanks landed on Indonesian islands. Earlier this month, parts of a SpaceX trunk capsule fell into paddocks in New South Wales, Australia.

“Every time we launch rockets, we roll dice,” Boley said. “And the problem is that we roll many dice, many times.”

Rockets are the transport vessel for everything that goes into orbit, including individual satellites and constellations of satellites, telescopes, engineering projects, and research modules. In 2021, there were more than 130 successful orbital rocket launches worldwide – a record – and 2022 is poised to deliver even more as space development is soaring.

“In the future, we may have companies launching rockets to build their own space stations, whether for tourism or in-orbit manufacturing,” Boley said.

Rocket trajectories can take many forms. Often they gradually break down during ascent, releasing heavy boosters or empty fuel tanks in a controlled process called staging. When staging occurs in the suborbital zone – where Earth’s gravity still has full or near full effect on the jettisoned machines – launch teams can plan precisely where they will land (over an ocean).

Other mission trajectories require certain stages of the rocket to be dropped into low Earth orbit (LEO) – a region loosely considered to be between 180 and 1,250 miles above Earth – where they are left to drift, effectively. , as space debris.

Technology is there to stem the danger. Not everyone uses it.

It’s not a technology problem. Some rockets, like SpaceX’s Falcon 9, have reignitable engines, which can direct re-entry to anywhere uninhabited (by humans) on Earth, and sometimes even full round trips with landing pads ready and waiting. .

But not all rockets are equipped with these technologies, and even if they are, “there is an additional expense associated with recovery,” Boley 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 bodies – including the particularly massive Long March 5B, which lacks reignition engines – are left behind at LEO. It is a political decision with which many countries, including the United States, seem to agree.

More than 1,000 rocket bodies and thousands of satellites are currently passing through LEO, making revolutions around the Earth every 90 to 120 minutes.

Gradually, these slow-burning orbital journeys – tracked most prominently and shared online by the Aerospace Corporation, an independent, government-sponsored non-profit organization – are slowed down by drag, the same aerodynamic force that naturally thwarts an airplane or racing car, and fall to Earth.

“It’s kind of funny, because an orbit is nothing more than falling towards something and constantly missing. And then eventually the gas trail makes it so, no, it’s going to hit this time.

Where space junk lands isn’t always left to chance

The eventual landing spots for many of these uncontrolled entries are not always random – with many launching and landing around the equator.

By studying the orbital trajectories of more than 1,500 rockets that have desorbed over the past 30 years, Boley and a team of researchers from the University of British Columbia estimated that there was between 10 and 20 percent chance losses from rocket debris. .

That’s a far cry from the 0.01% risk threshold that the US applies to its launches, an often overlooked loss assessment. “To my knowledge, there is no written record of the decision-making process that led to this. [0.01 percent] number having been applied to launches and reentries,” Boley said.

“But we can’t paint people in space as bad guys,” said Timiebi Aganaba, an assistant professor and senior global future fellow at Arizona State University who specializes in environmental and spatial governance. “[When the policies on space development were set], there were so few launches; it’s just not something that 10 years ago everyone would have been talking about.

But now, as space continues to be commodified and rockets fly more frequently, Boley and Aganaba agree that rocket debris is a problem for collective action. Boley said the solution will require the international community to come together and agree on risk-mitigating regulations.

It remains to be seen how and when these rules will be established and followed. It could take until “someone wins the lottery, so to speak,” to be unfortunately hit by space junk, Boley said. “Chances are it won’t be you, but someone will.”

This article has been updated. Thanks to Lillian Barkley for writing this article.

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