This explains the Lagrangian points
The L2 point is rapidly establishing itself as a pre-eminent location for advanced spaceprobes and ESA has a number of missions that will make use of this orbital 'sweet-spot' in the coming years. L2 will become home to ESA missions such as Herschel, Planck, Eddington, Gaia, the James Webb Space...www.esa.int
There was problem with Hubble initally due to a fleck of paint de-focussing the optics and blurring the images- they worked out the error and subsequently replaced a section of the telescope via the space shuttle to correct it. Unfortunately the JAMES WEB "scope is not in near-earth orbit- so it has to work faultlessly from the off---posssibly against any normal terrestrial odds.