After observatories retire, they can still spend hundreds, even millions, of years trailing the Earth.
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.