Webb has a primary mirror six times larger than the one found on the Hubble Space Telescope. In order for a primary mirror 21 feet in diameter to travel into space, it has to be broken up into multiple segments — in this case, 18 of them.
But for the 18 to act as one primary mirror, they have to be adjusted while in orbit. How this task is achieved is the focus of this episode of Behind the Webb.
NASA and Mary Estacion (STScI)
Publication: October 8, 2010