The possible realization of the wide FoV and large pupil Schmidt recently proposed for a space instrument opens the possibility of realizing even more large pupil optical telescopes in space. This development is important for the realization of space observatories dedicated to the observation of the terrestrial surface and events in the terrestrial atmosphere, as well for astronomical observations requiring a high sensitivity and good resolution on a very wide FoV. Optical systems of 50° FoV with pupils of tens of meters diameter can be obtained with a huge primary mirror of a Schmidt telescope by assembling and opening in space several ‘active’ sub-mirrors of relatively large dimensions. For fundamental research in physics it is of paramount importance the detection and measurement of the fluorescence light emitted by particle showers produced by extreme energy primary cosmic rays, and among them detection and measurement of events produced by ultra-high energy neutrinos, in particular in the energy range of 1018-1019eV (the so called cosmogenic neutrinos produced by the energy loss of charged cosmic rays produced at large distance (>100 Mpc) from the Earth). Some examples of such possible optical systems are evaluated and discussed in detail.