Removing these 50 objects from orbit would cut danger from space junk in half

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). Two more came from US launchers, one from Russia, one from India, and one from Iran.

This trend is likely to continue as China steps up deployment of two megaconstellations—Guowang and Thousand Sails—with thousands of communications satellites in low-Earth orbit. Launches of…