Issue 131

3 Oct 2025: Stephen Clark of Ars Technica (and friend of the Flash) released an article describing how removing the 50 largest pieces of debris, as identified by Dr Darren McKnight (another friend of the Flash), would “cut danger from space junk in half.” The article also notes that countries (primarily China) are continuing to deposit massive spent upper stages into orbits which will be a collision threat for at least 25 years. As China fields its Guowang and other mega-constellations it will add to the debris problem. To date China has abandoned 9 Guowang related upperstages in orbits which will persist for at least 25 years. Excerpts below. – The 50 most concerning pieces of space debris in low-Earth orbit are dominated by relics more than a quarter-century old, primarily dead rockets left to hurtle through space at the end of their missions. – Per Dr Darren McKnight: “76% of the objects in the top 50 were deposited last century, and 88% of the objects are rocket bodies.” – The 50 objects identified…are the ones most likely to drive the creation of more space junk in low-Earth orbit (LEO) through collisions with other debris fragments. – Larger debris at higher altitudes pose a higher long-term risk because they could create more debris that would remain in orbit for centuries or longer. – Russia and the Soviet Union lead the pack with 34 objects listed in McKnight’s Top 50, followed by China with 10, the US with three, Europe with two, and Japan with one. Russia’s SL-16 and SL-8 rockets are the worst offenders, combining to take 30 of the Top 50 slots. – If someone sent missions to retrieve all 50 of the objects, the overall debris-generating potential in low-Earth orbit would be reduced by 50 percent, according to McKnight. If just the Top 10 were removed, the risk would be cut by 30%. – More from Dr McKnight: “The bad news is, since January 1, 2024, we’ve had 26 rocket bodies abandoned in low-Earth orbit that will stay in orbit for more than 25 years.” The 25-year discriminator is important because that is the guideline promulgated by the Inter-Agency Space Debris Coordination Committee. – US and European governments have policies requiring launch companies to deposit their spent upper stages to altitudes low enough to naturally reenter the atmosphere within 25 years, or deorbit their rockets altogether. For example, SpaceX routinely deorbits the upper stages of its Falcon 9 rocket…driving them back into the atmosphere over an unpopulated part of the ocean. – China, on the other hand, frequently abandons upper stages in orbit. China launched 21 of the 26 hazardous new rocket bodies over the last 21 months, each averaging more than 4 metric tons (8,800 pounds)…most of the rockets used for Guowang and Thousand Sails launches have left their upper stages in orbit. – “We know the Chinese have the capability to not leave rocket bodies,” McKnight said. One example is the Long March 5 rocket, which launched three times with batches of Guowang satellites. On those missions, the Long March 5 flew with an upper stage called the YZ-2, a high-endurance maneuvering vehicle that deorbits itself at the end of its mission. The story isn’t so good for launches using other types of rockets. With the other ones, they always leave a rocket body,” McKnight said. “So, they have the capability to do sustainable practices, but on average, they do not.”