Webb's Science Tools

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Webb's four science instruments will observe a range of infrared wavelengths, which are longer than the visible wavelengths of light we see with our eyes.
Infrared wavelengths are longer than the optical wavelengths of the spectrum that are visible to humans. Although we cannot see infrared with the naked eye, we can sense it as heat. Infrared wavelengths are broken down into near-, mid-, and far-infrared ranges.

Webb's four scientific instruments will examine the universe across a range of near- and mid-infrared wavelengths (and even some of the red band of visible light). Each instrument has unique features that will allow astronomers to study a variety of astronomical objects in different ways.

Near Infrared Camera (NIRCam)

NIRCam will look at near-infrared wavelengths (called "near-infrared" because these wavelengths are near the red end of the visible spectrum). It will detect light from the earliest stars and galaxies in the process of formation, stars in nearby galaxies, as well as young stars in the Milky Way, and objects from a distant region of our solar system called the Kuiper Belt.

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Positioned behind the primary mirror, Webb's four science instruments will receive the light collected by the telescope and use a variety of tools — cameras, spectrographs, and coronagraphs — designed to maximize the scientific knowledge gleaned from every observation.

Near Infrared Spectrograph (NIRSpec)

NIRSpec is a "multi-object near-infrared spectrograph." A spectrograph is a device that breaks light up into its component colors. NIRSpec will see near-infrared wavelengths and will be able to observe more than 100 objects simultaneously thanks to its innovative microshutter assembly. It is designed to study, among other things, star formation and the chemical composition of young, distant galaxies.

Mid-Infrared Instrument (MIRI)

MIRI will have a sensitive camera and a spectrograph that will study mid-infrared wavelengths, examining distant stellar populations, the physics of newly forming stars, and the sizes of faintly visible comets and Kuiper Belt objects. MIRI is also equipped with a coronagraph, which blocks the glare of bright objects to allow clear observations of faint objects close to it.

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Webb's four science instruments are housed together in a unit known as the Integrated Science Instrument Module. Credit: Chris Gunn, NASA

Fine Guidance Sensors/Near-Infrared Image and Slitless Spectrograph (FGS/NIRISS)

FGS is Webb's guide camera, which helps point the telescope. NIRISS will gather spectra (like NIRSpec), and photograph the universe at near-infrared wavelengths (like NIRCam), observing both extremely bright objects as well as faint objects near bright stars, such as planets. FGS and NIRISS have different purposes but are packaged together into one unit.

Updated: May 04, 2016