We have presented a concept for a large telescope whose primary mirror is a thin reflecting membrane. The shape of the mirror is controlled by electrostatic actuators located on a parallel control membrane. Such a telescope could be built on the ground or as a deployable telescope in space. We show how the mirror of a space telescope, if constructed on the ground, can be folded, transported and deployed. Many studies remain to be done on this concept. Their results should allow to estimate the accuracy which can be reached. According to the results one could contemplate building radio, submillimeter, infrared or even optical and ultraviolet telescopes.