Overhead shot of the James Webb Space Telescope that shows the nine primary flight mirrors installed on the telescope structure in a clean room at NASA's Goddard Space Flight Center. Photo by Chris Gunn.
A robotic arm lifts and lowers the hexagonal-shaped segment that measures just over 4.2 feet across and weighs approximately 88 pounds. After being pieced together, the 18 primary mirror segments will work together as one large 21.3-foot mirror. The full installation is expected to be complete early in 2016.
The James Webb Space Telescope is the scientific successor to NASA's Hubble Space Telescope. It will be the most powerful space telescope ever built.