
http://www.nasa.gov/feature/goddard/2016/a-mechanical-harmony-to-nasas-webb-telescope-sunshield
Each step of the deployment will be manually initiated from engineers on Earth. That sequence runs automatically to its completion (with automated stoppage in case of a fault), then the system waits for the next command.
It will be like conducting an orchestra from a million miles away. "Thousands of components work together to deploy the sunshield," Cooper said.
The mechanisms that separate each of the sunshield's five layers do so with precision. Near the center of the sunshield each layer is separated by only a couple inches, but the layer-to-layer gap increases as you move away from the center, to about a foot between layers around the edges. It will take nearly two days to fully deploy the sunshield system when in orbit.
The Webb telescope state-of-the-art composite structure that supports the sunshield -operates with Swiss watch-like precision," said Paul Geithner, Webb telescope technical manager at Goddard. "The engineering of the sunshield is an intricate system with a simple but not easy-to-do purpose."
The stowed sunshield fits inside of a 5-meter (16.4-foot) rocket fairing, folded up against the sides of the telescope. When deployed in space it’s about the size of a tennis court (about 21 meters by 14.5 meters, or 68.9 feet by 47.5 feet).
"There has never been a composite structure this large and complex (for a NASA mission)," Cooper said.