JWST is being built to do things that are truly impossible on Earth. It is an infrared telescope that will image things that cannot be seen through Earth's atmo

JWST is being built to do things that are truly impossible on Earth. It is an infrared telescope that will image things that cannot be seen through Earth's atmosphere. JWST is not the first IR telescope (Spitzer Space telescope, retiring this month comes to mind, 0.85 m diameter primary), but its size will allow both improved resolution (diffraction limit falls like 1/diameter) and improved collection efficiency (grows like diameter^2). Without constellation-flying and interferometric telescopes (see Keck Observatory), one cannot get either one from an array of small telescopes. There are a lot of scientists grumpy about JWST because of its huge budget, but as long as JWST works, the view it gives of our universe will be spectacular. At this point, I think everyone really wants JWST to work, as so much has been sacrificed to make it possible.