Which 2003 NASA space telescope was launched to observe the infrared universe?

The 2003 NASA space telescope launched to observe the infrared universe was the Spitzer Space Telescope.

Spitzer launched on August 25, 2003, from Cape Canaveral aboard a Delta II rocket. It was originally called the Space Infrared Telescope Facility, or SIRTF, and was renamed after astronomer Lyman Spitzer, who had advocated space-based observatories decades earlier.

Infrared astronomy reveals objects and regions that visible-light telescopes can miss, including cool stars, dust clouds, planet-forming disks, and distant galaxies whose light has been stretched into infrared wavelengths. Spitzer’s instruments covered wavelengths from about 3.6 to 160 micrometres. Its 85-centimetre mirror and cryogenic systems allowed it to detect faint infrared radiation with exceptional sensitivity.

Spitzer was part of NASA’s Great Observatories program, alongside Hubble, Chandra, and Compton. It followed earlier infrared missions such as IRAS but used a distinctive Earth-trailing solar orbit. Its liquid helium coolant ran out in 2009, ending most of its original instrument capability, although two infrared channels continued operating until the mission ended in January 2020.