The James Webb Space Telescope includes four scientific instruments:
The Near Infrared Camera (NIRCam)
The Mid-Infrared Instrument (MIRI) has both a camera and a spectrograph that sees light in the mid-infrared region of the electromagnetic spectrum, with wavelengths that are longer than our eyes see. MIRI covers the wavelength range of 5 to 28 microns. Its sensitive detectors will allow it to see the redshifted light of distant galaxies, newly forming stars, and faintly visible comets as well as objects in the Kuiper Belt. MIRI's camera will provide wide-field, broadband imaging that will continue the breathtaking astrophotography that has made Hubble so universally admired.
The Near-Infrared Spectrograph (NIRSpec)
The Near InfraRed Spectrograph (NIRSpec) will operate over a wavelength range of 0.6 to 5 microns. A spectrograph (also sometimes called a spectrometer) is used to disperse light from an object into a spectrum. Analyzing the spectrum of an object can tell us about its physical properties, including temperature, mass, and chemical composition. The atoms and molecules in the object actually imprint lines on its spectrum that uniquely fingerprint each chemical element present and can reveal a wealth of information about physical conditions in the object.
The Mid-Infrared Instrument (MIRI)
The Mid-Infrared Instrument (MIRI) has both a camera and a spectrograph that sees light in the mid-infrared region of the electromagnetic spectrum, with wavelengths that are longer than our eyes see. MIRI covers the wavelength range of 5 to 28 microns. Its sensitive detectors will allow it to see the redshifted light of distant galaxies, newly forming stars, and faintly visible comets as well as objects in the Kuiper Belt. MIRI's camera will provide wide-field, broadband imaging that will continue the breathtaking astrophotography that has made Hubble so universally admired.
The Fine Guidance Sensor/ Near InfraRed Imager and Slitless Spectrograph (FGS-NIRISS)
The Fine Guidance Sensor (FGS) allows Webb to point precisely, so that it can obtain high-quality images. The Near Infrared Imager and Slitless Spectrograph part of the FGS/NIRISS will be used to investigate the following science objectives: first light detection, exoplanet detection and characterization, and exoplanet transit spectroscopy. FGS/NIRISS has a wavelength range of 0.8 to 5.0 microns, and is a specialized instrument with three main modes, each of which addresses a separate wavelength range. FGS is a 'guider,' which helps point the telescope.