After 16 years, NASA said goodbye to one of its great space observatories—the Spitzer Space Telescope. Late last week, the space agency downloaded the last bits of data and then put the spacecraft into hibernation.
On Jan. 30 at 5:34 p.m. EST (2:34 p.m. PST), Joseph Hunt, the observatory’s mission manager, declared that Spitzer’s watch over the cosmos had officially ended.
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Spitzer was one of NASA’s four great observatories, including the Hubble Space Telescope, the Chandra X-ray Observatory, and the retired Compton Gamma Ray Observatory. Together, they provided us with an unprecedented view of the universe across as many different wavelengths as possible—infrared, visible and UV, gamma rays and X-rays.
Spitzer forever changed how we see the cosmos, while helping us make all sorts of discoveries including distant galaxies, newborn stars and even exoplanets orbiting other stars.
The telescope launched in 2003, wandering through space for nearly two decades, as it examined the universe with its infrared eyes. Spitzer captured incredible images of some of the coldest and oldest objects in the universe, showing us things in new details that would otherwise be invisible.
When you look at objects in space, they will look very different depending on what wavelength of light you’re using. Things like planets and ancient galaxies are best observed in infrared. That’s because they don’t emit much visible light but do give off heat. And that’s what Spitzer was designed to hone in on.
Because it saw heat, Spitzer’s instruments have allowed scientists to collect data from areas of our universe normally clouded by interstellar gas and dust. Even in its final week of operations, the telescope beamed back incredible, one-of-a-kind observations.
Spitzer was originally designed to last just 2.5 years, but like many other NASA missions, it surpassed expectations. Eventually, the supply of coolant ran out, and the telescope could no longer keep its sensitive instruments working. However, that didn’t stop Spitzer not its team of scientists and engineers here on Earth. Despite this setback, Spitzer continued to gather valuable scientific data and operate for another decade beyond its initial mission.
Unfortunately, NASA ran out of money to operate the plucky little spacecraft, and the call was made to bench Spitzer back in 2016. It was to stay online until its successor, the James Webb Space Telescope, was activated. That launch was supposed to occur in 2019, but a series of setbacks have pushed it to at least 2021. As a result, Spizter’s end was delayed a few times before the final call was made to turn it off last Thursday.
It’s often referred to by astronomers as “the little telescope that could,” because Spitzer overcame so much during its lifetime and still kept cranking out the discoveries. (It was also often overshadowed by another great observatory—the Hubble Space Telescope—and its flashy images.)
Spitzer was designed to observe “the cold, the old and the dusty,” meaning objects that were too cold to emit visible light or those shrouded in dust. This included ancient galaxies, exoplanets orbiting other stars and much more.
Named for the late astrophysicist Lyman Spitzer, Jr., who first proposed the idea of space telescopes, Spitzer made its discoveries using a technique called spectroscopy, which allows scientists to measure the chemical composition of dust. Dust is a key ingredient in the universe: it envelops baby stars, provides the building blocks for planets and is the foundation for galaxies.
“Being able to see dust as a glowing element, means we can now see the spiral arms [of a galaxy] as the skeleton in an X-ray of an animal, where the dust is building up as ridges and lanes and spokes,” Robert Hurt, Spitzer imaging scientist, said during a news briefing prior to the shutdown. “These are tied to the processes that flows through a galaxy and builds up and creates dense regions of star formation.”
Spitzer made many discoveries. It was the first to detect direct light from exoplanets, it identified the most distant galaxy ever found and it even revealed an invisible ring around Saturn we never knew existed.
Plus it helped detect and characterize five of the seven planets in the TRAPPIST-1 system, a star system just 40 light-years from Earth. Thanks to Spitzer, we not only know those planets exist, but we also know they’re rocky, Earth-sized worlds.
Spitzer has been an invaluable tool, teaching us so much about the cosmos over the past few decades. But it’s work is not done. Spitzer’s eye may be closed forever, but the wealth of information it collected will be helping scientists for decades to come.