largest piece of orbital debris (mass)

The most massive pieces of debris in orbit as of January 2022 are 22 spent upper stages from the Russian/Soviet Zenit-2 rocket (active from 1985 to 2004). These rocket bodies have a dry mass (with no fuel) of 8,900 kg (19,621 lb), but all have at least some left over fuel on board, which means their actual mass is higher.

The second stage of the Zenit-2 rocket is 11.04 m (36 ft 2 in) in length and has a diameter of 3.9 m (12 ft 9 in) – that's about the length of a double decker bus, but quite bit wider.

Rocket bodies are a common but worrying type of orbital debris. With most modern launch vehicles, the upper stage restarts a few hours after depositing its payload into orbit, burning its engines to depletion against the direction of travel. This renders the stage largely inert, and slows it enough to make it renter the atmosphere within a few hours or days, rather than decades.

Older rocket stages do not generally make this re-entry burn, however. They remain in orbit loaded with whatever fuel was left over after orbital insertion. In addition to representing a navigation hazard on their own, if seals or valves corrode, and the fuel and oxidizer are allowed to mix, the rocket body may explode, scattering debris into the orbital paths of other satellites.

Propulsion-related explosions were found to have caused 44.2% of the "fragmentation events" that have been recorded in Earth orbit.

In December 2021, the United States Space Force confirmed that the partial destruction of the Chinese Yunhai 1-02 weather satellite on 18 March 2021 was caused by a collision with a piece of debris that had detached from a Zenit-2 rocket stage launched in 1996.