In August 2011, most likely atop an Ariane rocket rising from a launchpad in French Guyana, a 6.5-meter beryllium-and-gold mirror will sit folded into thirds like an elegant drop-leaf table, enduring the hellish forces of liftoff. The James Webb Space Telescope´s primary mirror is as big as a two-car garage, and there isn´t a roomy enough rocket fairing to carry it unfolded.
Once in space, the biggest telescope ever launched will unfold its mirror and unfurl a 2,400-square-foot sunshade as it drifts into orbit around Lagrange point 2, a spot one
million miles away from Earth where net gravitational forces are very weak. Why place it so far away, out of reach of any repair or upgrade mission? Because out there, the infrared telescope won´t feel Earth´s heat. The JWST, you see, will be looking out at the cosmos with an infrared camera, somewhat like the night-scopes that soldiers use to spot enemies in the dark, but incomparably more sensitive. (JWST project scientist John Mather calls his detectors â€miraculously goodâ€ and â€nearly perfect.â€) Any heat near the telescope will show up as noise-hence the million-miles-from-Earth orbit, sunshade, and onboard cryogenics that will cool the optics down to just 37 Celsius degrees above absolute zero (â€393