The Committee to Nuke Elysium

The density of space junk peaks around 620 miles up, in the middle of so-called low-Earth orbit. That’s bad, because many weather, scientific, and reconnaissance satellites circle in various low-Earth orbits. But that height also offers an opportunity. Below about 560 miles, small objects start to feel a significant drag from the Earth’s upper atmosphere. This drag causes them to slowly spiral toward Earth, and they eventually burn up in the atmosphere. The tungsten cloud could theoretically provide extra drag on objects orbiting above the 600-mile mark, slowing the itty-bitty debris down enough to fall below the 560-mile threshold. Tungsten wouldn’t clear up space instantly—objects at 560 miles can still circle for decades. But that’s vastly better than the centuries-long orbits of fast-moving objects even a little higher.

That said, there could be a downside to sending 20 tons of heavy metal dust aloft. Eventually, the tungsten cloud would itself fall toward Earth. Tungsten isn’t acutely toxic, and Ganguli and friends argue that, spread over many years, all that dust would not amount to much, especially compared with the hundreds of tons of micro-meteors and other space dust that already flits down onto Earth each day. But their five-page paper outlining the tungsten cloud devotes 54 words to the potential environmental impact, hardly an exhaustive look. Astronomers might also object, because the dust could interfere to an unknown degree with light streaming toward Earth from space. Fighting through swarms of microscopic dust could give satellites fits, too, though again, the naval scientists argue the impact would be negligible. (Most satellites point their instruments either straight down toward Earth or straight out into space, and therefore away from what would be mostly horizontal streams of tungsten dust.)

These scenarios all assume, though, that the tungsten dust will behave, and that the ionosphere or solar wind or whatever else won’t interact with it in funny ways. For instance, what if the tungsten doesn’t disperse in nice soft poofs but clumps together? Something similar happened with Project West Ford, a Cold War operation in the early 1960s to improve the reliability of radio communication (in case the Soviets sabotaged our undersea cables) by giving transmitters something solid to bounce signals off in space. To howls worldwide, the U.S. injected 480 million inch-long copper needles into orbit, clusters of which still circle Earth. Or, some observers have suggested that the dust could swell outward—perhaps even form a Saturn-like ring of Element 74 around Earth.

So, yeah, the idea still needs polishing. But if the growing amount of space junk wipes out a few billion-dollar satellites soon, a silvery tungsten cloud could be the least of many evils.