The Webb telescope has opened a new window onto the universe, but it builds on missions going back 40 years, including Spitzer and the Infrared Astronomical Satellite.
On December 25,
NASA’s first infrared telescope ever launched into Earth orbit, above the atmosphere that blocks most infrared wavelengths. Rho Ophiuchi’s thick clouds of gas and dust block visible light, but IRAS’ infrared vision made it the first observatory to be able to pierce those layers to reveal newborn stars nestled deep inside.
Twenty years later, Spitzer’s multiple infrared detectors helped astronomers assign more specific ages to many of the stars in the region, providing insights about how young stars throughout the universe evolve. Webb’s even more detailed infrared view shows jets bursting from young stars, as well as disks of material around them – the makings of future planetary systems.
Another example is Fomalhaut, a star surrounded by a disk of debris similar to our asteroid belt. Forty years ago, the disk was one of IRAS’ major discoveries because it also strongly suggested the presence of at least one planet, at a time when no planets had yet been found outside the solar system. Subsequent observations by Spitzer showed the disk had two sections – a cold, outer region and a warm, inner region – and revealed more evidence of the presence of planets.
Many other telescopes, including NASA’s
Visionary Infrared Astronomy Survey
When IRAS launched in 1983, scientists weren’t sure what the mission would reveal. They couldn’t predict that infrared would eventually be used in almost every area of astronomy, including studies of the evolution of galaxies, the life cycle of stars, the source of pervasive cosmic dust, the atmospheres of exoplanets, the movements of asteroids and other near-Earth objects, and even the nature of one of the biggest cosmological mysteries in history, dark energy.
IRAS set the stage for the European-led Infrared Space Observatory (ISO) and the Herschel Space Observatory; the Japanese-led AKARI satellite; NASA’s Wide-Field Infrared Survey Explorer (WISE), and the agency’s airborne SOFIA (Stratospheric Observatory for Infrared Astronomy), as well as many balloon-lofted observatories.
“Infrared light is essential for understanding where we came from and how we got here, on both the biggest and smallest astrophysical scales,” said Michael Werner, an astrophysicist at NASA’s Jet Propulsion Laboratory (JPL) in Southern California. Werner, who specializes in infrared observations, served as project scientist for Spitzer. “We use infrared to look back in space and time, to help us understand how the modern universe came to be. And infrared enables us to study the formation and evolution of stars and planets, which tells us about the history of our own solar system.”
On to Spitzer
If IRAS was a pathfinding mission, Spitzer was designed to dive deep into the infrared universe. Many of Webb’s planetary targets in its first year had already been studied with Spitzer, which pursued a broad range of science goals, thanks to its wide field of view and relatively high resolution. During its 16-year mission, Spitzer uncovered new wonders from the edge of the universe (including some of the most distant galaxies ever observed at the time) to our own solar system (such as a new ring around Saturn). Researchers were also surprised to find that the telescope was a perfect tool for studying exoplanets (planets beyond our solar system), something they hadn’t expected when building it.
“With any telescope, you’re not just taking data for the sake of it; you’re asking a particular question or a series of questions,” said Sean Carey, a former manager for the Spitzer Science Center at IPAC, a data and science processing center at Caltech. “The questions we’re able to ask with Webb are much more complex and varied because of the knowledge we acquired with telescopes like Spitzer and IRAS.”
For example, Carey said, “We studied exoplanets with Spitzer and Hubble, and we figured out what you can do with an infrared telescope in that field, what types of planets are most interesting, and what you can learn about them. So when Webb launched, we jumped into