In less than two weeks, one of NASA’s flagship infrared telescopes will close its eye on the cosmos. On January 30, Spitzer, one of the agency's Great Observatories, will transmit its final science and engineering data to mission control and be switched off.
The Spitzer Space Telescope has changed infrared astronomy for the better. Launched into space on August 25, 2003, it has in its 6,000 days in orbit studied everything from distant galaxies to our planetary neighbors.
Spitzer provided a new way for astronomers to study the universe. Among its many accomplishments are detailed studies of star-forming nebulae and what goes on inside them. It delivered the largest and most detailed infrared portrait of the Milky Way, consisting of over 800,000 snapshots, and also discovered the Phoebe ring of Saturn.
To observe the universe in infrared, a telescope needs to be cold, and Spitzer achieved that in two ways. First, it was put in an Earth-trailing orbit so that it didn’t have to deal with Earth’s own heat load. It was also kept cool with a liquid helium coolant. For this reason, the mission was always envisioned as having a limited shelf-life.
It was planned to operate for 2.5 years with the expectation that the program could be extended to double that. It ran out of coolant five years, eight months, and 19 days after it launched. And while it couldn’t perform far-infrared observations without the coolant, one instrument kept operating and continued to work tirelessly. The Spitzer Warm Mission lasted more than twice as long as the primary mission and is marked by great successes.
In particular, Spitzer lent its skills to the discovery and study of exoplanets. The famous TRAPPIST-1 system has seven of these exoplanets, five of which were discovered with Spitzer data while two more were confirmed by the mission. The system remains the largest system of terrestrial planets ever found around a single star. The observatory was responsible for the first studies of the atmospheres of planets from outside the Solar System.
Spitzer is one of NASA's four Great Observatories. The Compton Gamma Ray Observatory was launched in 1991 and concluded its mission in 2000 when it was de-orbited. The Chandra X-ray Observatory and the Hubble Space Telescope continue to work despite their ages. Chandra is now in its third decade of operation and Hubble will soon enter its fourth.
Spitzer won’t have a direct successor but several infrared observatories will be launched in the next few years. No matter what comes next its legacy won’t be forgotten for decades to come.
NASA will pay tribute to Spitzer and the astronomers and technicians that worked on it at 1pm EST on Wednesday, January 22. The event to celebrate this incredible legacy will air live across all of NASA's main social media channels.