SOMETIME THIS FALL, if the launch date doesn't slip again, NASA's James Webb Space Telescope-the most powerful, most expensive, and most anticipated telescope ever to gaze out into the universe-will lift off from French Guiana on an Ariane 5 rocket. Twenty-six years in design, delayed countless times, the JWST, as astronomers typically refer to it, will dwarf the Hubble Space Telescope in size, resolution, and ability to see very faint objects. Unlike Hubble, which operates primarily in the visible spectrum, Webb will use cameras and spectrographs tuned to near- and mid-infrared wavelengths to view some of the oldest objects in the cosmos, with a sensitivity 1,000 times better than past infrared space telescopes. Webb's shiny gold-covered mirrors will collect photons that have been journeying our way since a few hundred million years after the Big Bang.
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