The James Webb telescope will have a significantly larger field of view than the Hubble camera and much better spatial resolution than the Spitzer infrared space telescope, according to astronomers on the JWST team. Your primary mirror gives you approximately 7 times the collection area over currently available mirrors. Its size is colossal: the 18 hexagons that make up the 6.5-meter primary mirror are almost triple that of Hubble. The hexagons will unfold once in orbit due to the size of this large telescope.
The key piece
It's called MIRI (Mid Infrared Instrument), a tool designed to measure the mid-infrared wavelength range. It is one of the four key detectors at JWST that will allow us to look back a few hundred million years after the Big Bang . In total, its four instruments are: NIRSpec (Near Infrared Spectrograph), MIRI (Mid-Infrared Instrument), NIRCam (Near-Infrared Camera), and FGS / NIRISS (Fine Guidance System / Near-InfraRed Imager and Slitless Spectrograph).
