A collection of defunct spacecraft, their mission to chronicle the wonders of the universe long ended, glide silently in Earth’s vicinity. This week, NASA will turn off another, the Spitzer telescope, which has spent 16 years observing the cosmos. The telescope trails the Earth, looping around the sun, and little by little, it has drifted away from us.
The growing expanse, now hundreds of millions of miles wide, has made it trickier for engineers to operate Spitzer and point it at the right places—the sun, to charge itself; Earth, to transmit data; and the dusky universe beyond, to collect even more. So they’ve decided to junk it.
Objects in space, even very expensive, prized telescopes, are considered debris when they no longer have a purpose or function. Some, like Spitzer, were lofted into high altitudes or special orbits, and will stay out there for anywhere from hundreds to millions of years.
Kepler, the NASA telescope that discovered thousands of planets before it ran out of fuel in 2018, coasts along behind Earth. Herschel and Planck, two observatories from the European Space Agency, ceased operations in 2013, but still hang a million miles away at a spot in space where a quirk of gravitational forces maintains objects in stable orbits, almost as if by magic. The Galaxy Evolution Explorer, a NASA telescope that did exactly as its name suggests until 2012, is expected to circle Earth for nearly 60 more years before burning up in the atmosphere. Copernicus, one of NASA’s earliest observatories, is still up there after ending its X-ray observations in 1981, going round and round Earth. The list goes on.