Which NASA space telescope launched in 2003 to study the universe mainly in infrared light?

NASA’s Spitzer Space Telescope launched in 2003 to study the universe mainly in infrared light.

Spitzer launched on August 25, 2003, as the final of NASA’s four Great Observatories. Its infrared instruments allowed astronomers to observe through dust clouds that block visible light, revealing star-forming regions, cool objects, and distant galaxies.

The telescope used a supply of liquid helium to cool its most sensitive detectors. After the coolant was exhausted in 2009, Spitzer continued operating in a reduced mission with instruments that could work at warmer temperatures. NASA ended the mission on January 30, 2020.

Spitzer is sometimes confused with the James Webb Space Telescope because both are strongly associated with infrared astronomy. Webb is a much larger and newer observatory, while Spitzer was a pioneering space-based infrared telescope that operated for more than 16 years.