NASA’s Spitzer space telescope ended its mission with its final shutdown, which happened when in the USA it was afternoon. Launched on August 15, 2003, it’s been an instrument crucial for infrared astronomy in studies of various kinds ranging from those of solar system’s objects to those of distant galaxies passing through those of exoplanets.

I already wrote a celebration of the Spitzer space telescope on the occasion of the 15th anniversary of its launch. Its last mission, named “Spitzer Beyond”, was originally supposed to end in 2018 but the constant delays in launching the James Webb space telescope convinced NASA to extend it for another year.

The continuation of the mission of the Spitzer space telescope was becoming increasingly complex. It’s in a heliocentric orbit, where in essence it orbits the Sun chasing the Earth, but it’s moving away from it far more than it was in the plans of a mission that was supposed to last a few years. This is a problem that has become increasingly serious in recent years because Spitzer had to move towards the planet to send the data it collected. In recent years this meant that solar panels were no longer oriented towards the Sun during that operation and had to use batteries to accomplish it, contributing to their degradation. Furthermore, a part of the telescope was heated by the Sun interfering with the instruments on board and taking longer to resume its operations after sending the data. In short, it’s not a matter of budget but of growing difficulties in using an instrument whose life lasted well beyond what was expected.

The observations made with the Spitzer space telescope, which have continued almost to the last moment, will keep on being useful for many more years. In over 16 years of mission, it collected a wealth of data on many cosmic objects that will keep on being used in future research. Over time, the ingenuity of the team that ran the mission made it possible to expand its use, for example as a planet hunter, a type of task that seemed unthinkable at the time of its launch and that instead became significant in the last few years of its mission. In short, it leaves a remarkable legacy.