Recent RadioAstron discoveries made for 3C 273 and 0529+483 at 18 cm have brought the refractive scattering substructure in AGN to the scene. The refractive noise mimics the true emission of the jet, thus spoiling brightness temperature estimates. To account for the substructure one needs to get the properties of the scattering material on the spatial scales of several AU, which became available only with RadioAstron. However, the experiment to estimate these properties requires a series of observations which densely sample a vast range of the projected baselines. I will present the idea and design of the RadioAstron proposal to study the scattering substructure and will give an overview of its current status.