No one has yet been killed by re-entering space junk

EVERY DAY a tonne or two of defunct satellites, rocket parts and other man-made orbiting junk hurtles into the atmosphere. Four-fifths of it burns up to become harmless dust, but that still leaves a fair number of fragments large enough to be lethal. It is testament to how much of Earth’s surface is sea, and how sparsely populated the remainder remains, that the only recorded victims of this artificial hailstorm are five sailors aboard a Japanese vessel, who were injured in 1969, and a woman in Oklahoma who was grazed by a piece of falling rocket in 1997. But it is also testament to luck—and the odds of that luck holding are shortening.Population growth means that the fraction of Earth’s surface which space debris can hit harmlessly is shrinking. At the same time, more spacecraft are going up (111 successful launches in 2018, compared with 66 a decade earlier, and with many launches carrying multiple payloads). And payloads themselves are increasingly designed so that equipment which has fulfilled its purpose falls out of orbit years or decades sooner than it otherwise would, lest it collide with functioning spacecraft.