If the Webb telescope sunshield doesn't open, here’s what NASA will do (mashable.com)
"Like working on a jammed desk drawer, the ground crew could push or pull harder on devices to try to unstick them. Or imagine gently shaking that drawer to loosen the clutter lodged in it. The crew could also initiate a low-level vibration — a “shimmy” — by firing its rockets in different sequences."
So the ground crew can built in the "push harder" and "shimmy and shake" options, but what if it needs a good, swift kick to get things moving?
