Spitzer Space Telescope

Key facts

Mission & specifications

Mission

The Spitzer Space Telescope was NASA's great infrared observatory, the last of its four 'Great Observatories' alongside Hubble. Launched on 25 August 2003, it carried an 85-centimetre telescope chilled by liquid helium to just above absolute zero, so its own warmth would not blind it to the faint heat of the cosmos. To stay cold it was placed in an unusual orbit, trailing the Earth around the Sun and slowly drifting away from it. Infrared light passes through dust that blocks visible light, so Spitzer could see into the hearts of star-forming clouds, peer at distant galaxies, and study cool objects like brown dwarfs and planet-forming disks. It became a pioneer of exoplanet science, among the first instruments to detect light directly from a planet around another star and to map an exoplanet's temperature. It also discovered the largest of Saturn's rings, a vast, faint halo of dust, and in 2017 it precisely measured the seven Earth-sized planets of the TRAPPIST-1 system. Its helium coolant ran out in 2009, but it kept working in a 'warm' mode for another decade. After more than sixteen years, NASA switched Spitzer off on 30 January 2020.

1. 2003Launch into an Earth-trailing orbitLaunch

   The last of NASA's Great Observatories sets out, its detectors chilled by liquid helium.

2. 2005Light detected from an exoplanetMilestone

   Among the first instruments to detect light directly from a planet orbiting another star.

3. 2009Helium runs out — the 'warm mission' beginsMilestone

   With its coolant gone, Spitzer keeps observing on two short-wavelength channels for a decade more.

4. 2009Saturn's largest ring discoveredMilestone

   Finds a vast, faint halo of dust far beyond the bright rings — the giant Phoebe ring.

5. 2017Measuring the TRAPPIST-1 planetsMilestone

   Pins down the sizes and orbits of seven Earth-sized worlds around a nearby red dwarf.

6. 2020Switched offMission end

   Retired after more than sixteen years of infrared discovery.

Images

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