Where space stations, rockets rust in peace

After a week of speculation, the core stage of a Chinese Long March 5 rocket, dubbed CZ-5B, landed in an uncontrolled reentry in the Indian Ocean, near the Maldives. The rocket had transported part of China’s new space station into orbit. But its core stage — about 30 meters long and 5 meters in diameter — could have landed anywhere, even on land. A year ago, a pipe from a previous Long March 5 rocket reportedly landed on someone’s house in Cote D’Ivoire. Hence, all the fear and criticism this year. NASA’s administrator, Bill Nelson, said it was “clear” that China was “failing to meet responsible standards regarding their space debris.” Nelson is not alone with his opinion. But the picture is more complicated than that. And the US is by no means innocent.

“There is no doubt,” says Alice Gorman, an associate professor at Flinders University in Adelaide, Australia, and author of Dr Space Junk vs the Universe, that “China has been a bit naughty.” “They are relying on the fact that most stuff either burns up [on reentry through the Earth’s atmosphere] or falls over ocean or sparsely populated land. But given their experience last year, when the retaining rods [from another rocket] hit a village in Cote D’Ivoire, that optimism is a bit misplaced,” Gorman told DW. Chinese aerospace experts rejected any international concern before the rocket core came down on May 9. One expert, Song Zhongping, was quoted in the Global Times as saying that it was “completely normal” for rocket debris to return to Earth.

And Zhongping is right — it is quite normal for bits of rocket, satellites and even space stations to splash back down. And China’s not even the worst offender. There are other nations and commercial companies doing it, too. “As I’ve said, the main polluters of space are the US and USSR/Russia,” says Gorman. The majority of space junk lands somewhere in the ocean. That’s simply because there’s more ocean than land. Mission designers will target specific regions, such as the South Pacific Ocean Uninhabited Area (SPOUA), near Point Nemo. Point Nemo is one of the Earth’s “poles of inaccessibility.” It is the farthest point from land in any direction on the planet. In a blog post from 2018, the European Space Agency writes more than 260 spacecraft have fallen in that zone since 1971. The number increases annually.

Point Nemo is known as the “spacecraft cemetery.” But it’s not the only ocean region where spacecraft fall. “Point Nemo? It’s sort of there, but it’s like everywhere in the South Pacific between New Zealand and Chile,” says Jonathan McDowell, an astrophysicist at the Harvard-Smithsonian Center for Astrophysics in Cambridge, USA. A number of boosters have fallen near populated areas in China, once near a school, and at a test site in Kazakhstan. Both cases released toxic orange clouds of what’s called “BFRC.” Once a rocket enters orbit, things get more complicated. And the deeper a rocket goes, the harder it gets to deorbit.

It’s more expensive, because you have to keep the rocket alive, as it were, with extended battery life and/or a restartable engine that gets fired after the rocket has delivered its “payload” — a satellite or supplies for the International Space Station. But only then can you control its reentry. Many rocket stages just get left up in orbit. There is a trend in the industry to change, says McDowell. It wants to leave less debris in space for fear of a growing congestion that could either interfere with earthly communications systems or impede further space exploration. But that means more stuff will have to come down. There is even talk of deorbiting the International Space Station in 2028, and dropping it at a final resting place in the South Pacific. The impact on the ocean is — despite assertions that space junk becomes nice, natural habitats for marine life — largely unknown. So, there are potential environmental impacts, says Gorman, “but I don’t think people have thoroughly assessed that yet.”