A historical overview of MURN-YuMO instrument (including some technical and scientific development prospects) is presented. Numerous references are cited which demonstrate a tireless activity on the first in the world SANS machine functioning at a neutron pulsed reactor. The relevant scientific activity trajectories of Yu.M.Ostanevich and his colleagues are retraced and put into perspective. It is a great pleasure for us to give a brief introduction to Prof. Yu.M. Ostanevich scientific activity related to small-angle neutron scattering. Three of the authors of this introduction (AK, AI and VG) knew and worked with him, two of us (TM and MB) came to the Laboratory when he has left us, but we all appreciate very much the beautiful science, the YuMO instrument and scientific spirit, which Yu.M. Ostanevich created for us and our colleagues. Recall that the acronym YuMO of small angle neutron scattering spectrometer (MURN) was given in honour of Yu.M. Ostanevich. Prof. Yu.M. Ostanevich had a broad knowledge and deep understanding of physics. This allowed him to enter quickly into a new scientific field and work there efficiently. He started his research in the sixties with the studies of Mössbauer effect in condensed matter. One of his activities was investigation of the effect of gravity on self-diffusion at critical point of water and neutron resonances. Since 1974 he was concentrated on creating a first time-of-flight small-angle spectrometers at IBR-30 and IBR-2 pulsed reactors. We and our colleagues, who are working at the YuMO SANS instrument at IBR-2, admire outstanding quality and longevity of Yu.M. Ostanevich's scientific and technical ideas