Up until a decade ago, China had never launched as many as 20 orbital rockets in a single year. Beginning in 2022, however, the country launched 64 rockets, and last year hit a record 93, making it the second-most productive space power on Earth. Further growth is anticipated from both state-owned enterprises and a rapidly expanding private launch sector. There's nothing inherently wrong with this - the United States, and SpaceX in particular, has seen similar growth.
But here's the catch: China appears to be ignoring long-established norms about disposing of rocket upper stages. These are the parts of the vehicle that separate from the first stage and push a satellite into orbit - and they're being left to drift. In the early decades of spaceflight, the Soviet Union, the United States, and other spacefaring species paid little heed to these "rocket bodies," ejecting them into all manner of orbits to decay slowly over decades. Over the last 20 years, most countries have taken a more responsible approach, because having large, multi-ton blocks of metal spinning uncontrollably in low-Earth orbit turns out to be a problem.
The Soviet Union (and later Russia) remains the biggest offender, with about 800 metric tons of rocket bodies in long-lived orbits between 600 km and 2,000 km above Earth's surface, according to the European Space Agency's Space Debris Office and Jonathan McDowell's General Catalog of Artificial Space Objects. The United States has about 57 metric tons in those orbits. These numbers are more or less holding steady - or, in Russia's case, slowly declining as stages fall out of orbit.
China's rocket body mass, by contrast, is growing strikingly. In the past five years, China's mass in long-lived orbits has risen from less than 100 metric tons to 252 metric tons, according to a new analysis by Space Domain Awareness expert Jim Shell. "China continues to abandon many rocket bodies in high low-Earth orbit," Shell wrote on LinkedIn. "The total mass of orbital debris is a key variable influencing the long-term sustainment of space. There is broad agreement that abandoning rocket body upper stages in long-lived orbits is not a best practice."
The recent growth is driven by China's increased launch rate as it begins to deploy satellite megaconstellations, Shell said. Constellations such as Guowang and Spacesail are typically at higher altitudes, above 800 km, and China may launch 1,000 or more rockets over the next decade - which, if current practices continue, will dump a lot more dead metal up there.
Satellites outnumber spent rocket bodies by more than 10-to-1, but satellites are typically smaller and can be maneuvered to avoid collisions. Rocket bodies are dead objects that cannot be steered. For this reason, the vast majority of space objects rated as "most concerning" pieces of debris are rocket bodies. The best practice for modern launches is to reserve some propellant in the upper stage to dispose of it - either by returning it to an oceanic location like Point Nemo (as Falcon 9 does for Starlink launches) or by putting it into a heliocentric orbit. China, apparently, did not get that memo.