The round, gold coated secondary mirror that will fly aboard NASA's James Webb Space Telescope looks like a giant sun in this photo where technicians at NASA were securing it to a platform.
What appears to be a track circling the mirror looks like the orbit a planet would take around the sun. The rounded shipping canister that the housed the mirror actually fit on that rounded "track."
Like the 18 hexagonal primary segments that make up the biggest mirror on the Webb telescope, the secondary mirror is perfectly rounded. The mirror is also convex, so the reflective surface bulges toward a light source. It looks much like the curved mirrors on the walls near parking garage exits that let motorists see around corners.
This mirror is coated with a microscopic layer of gold to enable it to efficiently reflect infrared light (which is what the Webb telescope's cameras see).
"The thickness of the gold coating on the mirrors is only 100 nanometers thick, or a 10th of a micron, which is 1/10,000th of a millimeter," says Paul Geithner, deputy project manager, technical, for the Webb telescope at NASA's Goddard Space Flight Center in Greenbelt, MD. "A human hair is roughly 1,000 times thicker."
The mirror arrived at Goddard on Nov. 5, 2012. The mirror previously resided at Ball Aerospace & Technologies Corp. of Boulder, CO, which manufactured it. The Webb telescope is the world’s next-generation space observatory and successor to the Hubble Space Telescope. The most powerful space telescope ever built, the Webb telescope will provide images of the first galaxies ever formed and study planets around distant stars. It is a joint project of NASA, the European Space Agency and the Canadian Space Agency.
(Image credit: NASA/Chris Gunn Text credit: NASA/Rob Gutro)