The observatory was launched on August 25, 2003, for a 2.5-year primary mission. Its high sensitivity and ability to observe in the infrared have enabled it to study some of the universe’s most distant galaxies, observe exoplanets, and make numerous discoveries, including Saturn’s largest known ring, stellar nurseries, massive galaxy clusters, and more.
While the telescope was not initially designed to study exoplanets, it has spent more than half its time doing so, noted Spitzer project manager Lisa Storrie-Lombardi of NASA’s Jet Propulsion Laboratory (JPL).
One of NASA’s four Great Observatories in space, Spitzer has successfully peered through dust to study star-forming regions, black holes, and massive galaxy clusters.
By observing light that traveled 13.4 billion years from ancient galaxies, scientists can view these galaxies as they appeared just 400 million years after the Big Bang.
“In its 15 years of operations, Spitzer has opened our eyes to new ways of viewing the universe. Spitzer’s discoveries extend from our own planetary backyard, to planets around other stars, to the far reaches of the universe. And by working in collaboration with NASA’s other Great Observatories, Spitzer has helped scientists gain a more complete picture of many cosmic phenomena,” said Paul Hertz, director of the Astrophysics Division at NASA’s Washington, DC, headquarters.
One particular Spitzer discovery that surprised scientists was its observation of young galaxies much larger than expected, indicating they formed very early in the history of the universe.
The telescope has also observed some of the most distant known exoplanets. It was instrumental in the discovery of the TRAPPIST-1 system, in which seven planets orbit close to one another, three of which are located in the star’s habitable zone, where temperatures allow liquid water to exist on their surfaces.
A key to the success of NASA’s four Great Observatories is each one’s ability to observe in different wavelengths. By combining all their observations, scientists have been able to gain a more comprehensive understanding of the universe.
“The Great Observatories program was really a brilliant concept. The idea of getting multi-spectral images or data on astrophysical phenomenon is very compelling, because most heavenly bodies produce radiation across the spectrum. An average galaxy like our own Milky Way, for example, radiates as much infrared light as visible wavelength light. Each part of the spectrum provides new information,” stated Spitzer project scientist Michael Werner, also of JPL.