The Webb telescope has a series of mirrors to get the light from the universe into the observatory's cameras. After the light reaches the primary mirror, it is then bounced up 25 feet to the secondary mirror. This much smaller mirror is deployed using three arms, or struts. Engineers at NASA's Goddard Space Flight Center are conducting tests to ensure a successful deployment after launch. This episode of Behind the Webb shows us the scope of the task at hand and how the test is being done to simulate a zero-gravity environment.
NASA and Mary Estacion (STScI)
Publication: May 19, 2015