A Clear Reflection on Webb Telescope's Secondary Mirror

A Clear Reflection on Webb Telescope's Secondary Mirror

The sole secondary mirror and another primary mirror that will fly aboard NASA's James Webb Space Telescope arrived at NASA's Goddard Space Flight Center in Greenbelt, Maryland on November 5, 2012. In this photo, technicians inspect the secondary mirror using flashlights. Unlike the 18 hexagonal primary segments that make up the biggest mirror on the Webb telescope, the secondary mirror is a perfectly rounded, convex segment. The mirror is made of beryllium, which was selected for its stiffness, light weight and stability at cryogenic temperatures. Bare beryllium is not very reflective of near-infrared light, so each mirror is coated with gold. The microscopic gold coating enables the secondary mirror to efficiently reflect infrared light (which is what the Webb telescope's cameras see). 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. Webb is an international project led by NASA with its partners, ESA (the European Space Agency) and the Canadian Space Agency. NASA Photo by Chris Gunn/UPI