Image: Webb telescope crew flexes robotic arm at NASA

The robotic arm lifts and lowers a golden James Webb Space Telescope flight spare primary mirror segment onto a test piece of backplane at NASA's Goddard Space Flight Center in Greenbelt, Md.

While the team practices the positioning that will be done on the actual telescope in the cleanroom, Dave Sime, an assembly crew chief, inspects the mirror placement from the underside of the backplane.