Yesterday, after 6002 days since launch, NASA engineers switched off the Spitzer Space Telescope.
I knew this day was coming. I mean, of course it was: Everything is finite, and spacecraft doubly so. They have moving parts, or limited fuel, or, in this case, budgetary constraints to their operation. They may operate for years, or decades, but the day will come.
Launched in 2003, Spitzer was designed to look at the Universe in the infrared, where things look mighty different than with our eyes. Cold dust that is dark, even opaque, in visible light glows eerily and ethereally in the infrared. Brown dwarfs, objects more massive than planets but less so than stars, give off their peak glow there, making them easy pickings for Spitzer. Distant galaxies, so far away that the Universe has aged billions of years since their light left them, and the cosmic expansion has stretched their light out into longer wavelengths, reveal their secrets in the infrared. Exoplanets light years from Earth, warmed by their host stars, stand out to Spitzer like a lit match in a dark room.
It used liquid helium to cool its detectors, because the telescope itself glows in the infrared — ...