A new listing of the 50 most concerning pieces of space debris in low-Earth orbit is dominated by relics more than a quarter-century old, primarily dead rockets left to hurtle through space at the end of their missions.

“The things left before 2000 are still the majority of the problem,” said Darren McKnight, lead author of a paper presented Friday at the International Astronautical Congress in Sydney. “Seventy-six percent of the objects in the top 50 were deposited last century, and 88 percent of the objects are rocket bodies. That’s important to note, especially with some disturbing trends right now.”

Russia and the Soviet Union lead the pack with 34 objects listed in McKnight’s Top 50, followed by China with 10, the United States 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. Here’s the Top 10:

1. A Russian SL-16 rocket launched in 2004
2. Europe’s Envisat satellite launched in 2002
3. A Japanese H-II rocket launched in 1996
4. A Chinese CZ-2C rocket launched in 2013
5. A Soviet SL-8 rocket launched in 1985
6. A Soviet SL-16 rocket launched in 1988
7. Russia’s Kosmos 2237 satellite launched in 1993
8. Russia’s Kosmos 2334 satellite launched in 1996
9. A Soviet SL-16 rocket launched in 1988
10. A Chinese CZ-2D rocket launched in 2019

The list published Friday is an update to a paper authored by McKnight in 2020. This year’s list goes a step further by analyzing the overall effect on debris risk if some or all of the worst offenders were removed. 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 percent.