Space junk, apparently from China and a NASA SpaceX mission, landed on Earth and landed.
There is a 10% chance that a person will be hit by falling space debris within a decade, the researchers calculated.
Experts say controlled re-entries, studying fallen debris and warning systems can lessen those chances.
It’s raining rocket parts, and space junk experts fear that someday a piece of debris falling from Earth’s orbit will hit a person.
The thruster of a 25-tonne Long March 5B rocket, which put part of China’s new space station into orbit in late July, crashed back to Earth on Saturday.
While part of the propellant likely burned as it fell into Earth’s atmosphere, reports indicate that parts of the rocket may have survived the fall and crashed near inhabited areas of Borneo, an island in Southeast Asia. Debris was found on the Malay and Indonesian sides of the island, as well as in the ocean near the Philippines. The locations of the debris reports were along the thruster’s atmospheric re-entry path, previously calculated by orbital debris experts.
“They sure look like rocket parts to me,” Ted Muelhaupt, a consultant to the Aerospace Corporation’s Office of Chief Engineering, told Insider, adding, “I have no reason to dispute that they are pieces of this rocket.”
In July, a shepherd in Australia discovered a mysterious piece of debris sticking out of the ground, nearly 3 meters high. On Wednesday, the Australian Space Agency said the giant piece of hardware came from the discarded trunk of a SpaceX Crew Dragon spacecraft, which carried astronauts for NASA last year.
Only China and SpaceX can confirm that these parts come from their spacecraft. But experts like Muelhaupt say they believe the reports.
“There’s no doubt in my mind,” Jonathan McDowell, a Harvard astronomer who meticulously tracks objects in Earth’s orbit, told Insider.
These are just a few striking examples of a widespread phenomenon. Every day, various man-made objects leave orbit and return to Earth, according to Muelhaupt, who works on the Aerospace Corporation’s reentry database.
Many space objects burn up in the atmosphere, but bits of material regularly survive the fall. Experts at the Aerospace Corporation say that up to 40% of the mass of a large space object falling from orbit will reach the ground. About once a week, an object weighing at least 1 ton falls out of orbit and re-enters the atmosphere, Muelhaupt said.
In a study published in the journal Nature in July, researchers calculated an approximately 10% chance that debris would hit one or more people within a 10-year period.
“If you roll the dice too many times, someone will get lucky,” McDowell said.
Crowded skies mean more space debris falling
Typically, after a launch, rocket boosters push themselves to the most remote part of the Pacific Ocean – a process called “controlled re-entry”. Smaller discarded objects, such as the torso of a Crew Dragon, must either burn up in the atmosphere or go into orbit around the Earth and remain there.
But in the case of the Long March 5B, China did not design the rocket booster for controlled re-entry. Instead, it fell back to Earth randomly each of the three times it was released. In May 2020, debris from one of these rockets was discovered near two villages in Ivory Coast, causing material damage.
Long March 5B thrusters are among the biggest objects to fall back to Earth, but uncontrolled re-entry is not unique to China. In 1979, NASA’s Skylab space station descended rapidly, scattering debris over Australia. Today, however, controlled re-entry is standard practice.
Despite the increase in space activity in recent years, extinct space objects are increasingly being brought to Earth under control. “While 30 years ago, a rocket stage would have been left in orbit and made an uncontrolled re-entry a few years later,” McDowell said.
Still, Muelhaupt fears there will be more frequent scrap metal incidents – like the piece of Crew Dragon that landed in Australia – in the future. In spaceflight, the standard acceptable level of risk to human life is one in 10,000. But when companies like SpaceX plan to launch tens of thousands of satellites into orbit, those odds mean that some of them will drop chunks of metal onto Earth.
Between various companies launching satellite constellations and more space agencies flying in spacecraft, there is an increasing chance that the debris will land somewhere densely populated.
“You do it often enough, you do it long enough, you’ll get lucky and drop it in the middle of a city park,” Muelhaupt said.
Taking out space trash
For now, the best way to prevent the space junk disaster is to convince all countries and companies to commit to practicing controlled re-entry.
“The People’s Republic of China did not share specific trajectory information when its Long March 5B rocket fell back to Earth,” said Bill Nelson, NASA Administrator, tweeted Saturday, adding that all space nations must participate in responsible space behavior.
“Doing so is critical to the responsible use of space and ensuring the safety of people here on Earth,” added Nelson.
Space companies and agencies can also study space debris to find out why it fell out of orbit and why certain parts didn’t burn up along the way. For example, Muelhaupt said the biggest piece of suspected SpaceX debris in Australia is a section where metal connects to carbon fiber. Why this annex separated from the rest of the spacecraft and survived the fiery fall to Earth is a question Muelhaupt wants to answer.
“I hope they catch it and then tell us,” Muelhaupt said.
A better understanding of falling debris can help inform warning systems in real time, both for people on the ground and for people flying planes. With passenger planes crisscrossing the planet all the time, there should be a space debris warning for pilots, Muelhaupt said. A collision is unlikely, but if it did happen the damage would be catastrophic, especially for a commercial passenger flight.
“The odds of hitting an unprotected individual in the open is one thing, but you have an aircraft in flight, now suddenly the consequences are much greater,” Muelhaupt said.
He fears it will take a disaster to pressure regulators and companies to make real changes.
“I hate to say it: when something bad happens to someone, that’s when we react,” said Muelhaupt.
Read the original article on Business Insider