John Metcalfe was CityLab’s Bay Area bureau chief, covering climate change and the science of cities.
A mysterious object expected to make a fiery reentry on November 13 is far from the only piece of space garbage zooming above us.
Perhaps there’s no better way to give first-time astronauts the heebie-jeebies than to show them the immense garbage field they’ll be drifting through. The U.S. government tracks more than 19,000 old satellites, hulking rocket bodies, and unknown detritus zipping around earth at about 17,000 mph—a chaotic racecourse well represented in this dizzying NASA visualization.
A hunk of manmade debris is expected to make a fiery entrance through the atmosphere on Friday, November 13, and NOAA is using it as an opportunity to remind folks of all the crud circling above our heads. (The object, called WT1190F, will likely disintegrate before it hits the Indian Ocean.) The threat isn’t just from big stuff, either; low-earth orbit is littered with hundreds of thousands of fragments that could pepper operational spacecraft. Writes NOAA:
For some, it is these smaller, unknown, and untracked objects that pose the biggest threat, for they can damage a satellite or a spacecraft, including manned missions such as the International Space Station. (See this detailed account from NASA of a close encounter between a piece of space debris and NOAA-NASA's Suomi NPP satellite in October 2014.)
Although the amount of space debris is not constant, it generally increases every year, sometimes generated from debris collisions, which can potentially create additional debris fragments. One terrifying, albeit hypothetical, scenario known as the Kessler syndrome posits that, should the density of objects in low earth orbit become high enough, collisions between objects could cascade, thereby increasing the likelihood of additional collisions and, ultimately, rendering the use of satellites and other space activities unfeasible. Yikes.
(People who watched the 2013 movie Gravity will recall a particularly violent illustration of the Kessler syndrome.)
If a spacecraft hits debris coming from the opposite direction, the roughly 22,370 mph-impact would be much stronger. In such an event, a pea-sized bit of garbage would smash into a surface like a “bowling ball moving at 300 miles per hour,” says NASA. The resulting jolt might puncture a hull as well as release a blinding energy flash, as shown in this test of a 17,000-mph projectile at one of the space agency’s ballistic ranges:
On the plus side, the objects we can track fall back to the planet at a rate of about one a day. Most are incinerated in the atmosphere or plop into sparsely populated areas and the sea. In some cases, operators can even steer decrepit satellites into deep-sea zones known as “spacecraft cemeteries.” One of these in the Pacific holds an astonishing 160-some relics, including the European Space Agency’s Jules Verne craft, whose spectacular 2008 reentry was captured on video.