NASA has put the 18th and final piece of the puzzle into place for the $8.8 billionJames Webb Space Telescope’s primary mirror – marking a major milestone on the way to the observatory’s launch in 2018.
The 21.3-foot-wide mirror is so big it couldn’t be fabricated in one piece. Instead, it’s made up of 18 hexagonal segments, each spanning a little more than 4 feet and weighing about 88 pounds. The last segment was carefully laid into place using a clawlike robotic arm at NASA’s Goddard Space Flight Center in Maryland on Feb. 3.
“With the mirrors finally complete, we are one step closer to the audacious observations that will unravel the mysteries of the universe,” John Grunsfeld, NASA’s associate administrator for science, said in a news release.